ACUS01 KWNS 241231
SWODY1
SPC AC 241230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Thu Oct 24 2024

Valid 241300Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS EVENING
INTO EARLY TONIGHT FROM EASTERN KS TO NORTHERN MO AND IA...

...SUMMARY...
Isolated large hail (1-1.75 inch diameter) and isolated strong gusts
(50-60 mph) will be possible from eastern Kansas into northern
Missouri and much of Iowa this evening into early tonight.

...Eastern KS/northern MO/IA this evening into tonight...
A midlevel shortwave trough over western WY this morning will
progress to the central Plains this evening and the mid MS Valley by
early Friday. Downstream from this midlevel trough, lee
cyclogenesis is expected across the central High Plains this
afternoon, which will aid in northward advection of a partially
modified Gulf air mass (boundary-layer dewpoints of 55-60 F).
Strong surface heating/mixing across KS/OK will result in a narrow
surface warm sector with moderate buoyancy (MLCAPE near 1000 J/kg)
by mid-late afternoon across eastern KS. The eastern extent of the
surface warm sector will be demarcated by a warm front into western
MO.

Surface-based thunderstorm development will be possible by roughly
22-00z along a surface trough/cold front across eastern KS, with
subsequent expansion of elevated convection farther northeast across
northern MO/southern IA through early tonight in a zone of
strengthening low-level warm advection. Isolated strong outflow
gusts (50-60 mph) will be possible with the initial storms across
eastern KS this evening in the zone of steeper low-level lapse
rates. Steep midlevel lapse rates, moderate buoyancy, and
sufficiently long/curved hodographs will support some potential for
embedded supercells capable of producing isolated large hail (1-1.75
inch diameter) into early tonight. The area from eastern KS to
northwest MO was considered for a SLGT risk upgrade, and this area
will be monitored closely in later outlook updates.

..Thompson/Goss.. 10/24/2024

$$
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ACUS01 KWNS 281230
SWODY1
SPC AC 281229

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0729 AM CDT Mon Oct 28 2024

Valid 281300Z - 291200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Discussion...
Deep convective potential will remain limited today with severe
storms not expected. This will be influenced by an amplifying
large-scale pattern, highlights by strong height falls over the
West, particularly across the Great Basin to central/southern
Rockies. In this scenario, steep lapse rate profiles may support a
few flashes of lightning with shallow convection near the Pacific
Coast today. Increasing forcing for ascent and steepening lapse
rates across the interior Great Basin/Four Corners may contribute to
isolated convection, some of which may generate lightning later this
afternoon into evening.

Later tonight, primarily after 03Z, elevated thunderstorms are
expected to develop and spread east-northeastward across the Upper
Great Lakes. This will be a byproduct of a robustly strong
southwesterly low-level jet and warm advection regime emanating from
the central Plains toward the upper Mississippi Valley.

..Guyer/Leitman.. 10/28/2024

$$
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ACUS01 KWNS 291224
SWODY1
SPC AC 291222

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0722 AM CDT Tue Oct 29 2024

Valid 291300Z - 301200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL AND SOUTHERN PLAINS...

...SUMMARY...
Thunderstorm development may occur late tonight from the Upper
Mississippi Valley south-southwestward across the central and
southern Plains, with some potential for storms to produce severe
hail and/or wind.

...Central/Southern Plains...
A prominent mid/upper-level trough centered over the Great Basin and
Southwest Deserts will continue generally eastward toward the
central/southern Rockies through late tonight. Preceding this upper
trough will be a nocturnally maximized strong southwesterly
low-level jet, with a strengthening lee trough and increasing
warm-sector low-level moisture in advance of a cold front (and
southern Plains surface trough/dryline), that will generally extend
by late tonight from the Upper Midwest southwestward across
Nebraska/Kansas into the southern High Plains.

Given limited initial height falls and modest-quality autumnal
low-level moisture, it is likely that a mid-level cap generally
based around 800 mb will persist regionally through the peak heating
cycle, with increasing prospects for deepening convection focused in
the overnight and early morning hours of Wednesday. This could start
across central Nebraska/northern Kansas near the cold front as early
as late evening or early in the overnight, with a subsequent
southward expansion across Kansas into western Oklahoma and possibly
the far eastern Texas Panhandle through the predawn hours, where a
conditional potential for near-surface-based storms may exist
coincident with roughly 60-63F surface dewpoints. Given the strength
of the wind field and increasing moisture/modest buoyancy
regionally, organized thunderstorms are possible with some localized
potential for severe hail and wind late tonight.

..Guyer/Leitman.. 10/29/2024

$$
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ACUS01 KWNS 011255
SWODY1
SPC AC 011254

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0754 AM CDT Fri Nov 01 2024

Valid 011300Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN HIGH PLAINS...

...SUMMARY...
Isolated severe hail and/or gusts are possible across parts of the
southern High Plains, from this evening into the overnight.

...Synopsis...
Today will mark the start of a substantial mid/upper-level pattern amplification over the CONUS. This will be mainly related to a
strong shortwave trough now digging southeastward over the Pacific,
offshore from OR, and south of a cyclone now covering the BC Coast
and adjacent waters. The cyclone will move inland and devolve to an
open-wave trough, but also, will phase better with the amplifying
shortwave trough. By the end of the period, this should result in a
major synoptic-scale trough from southern BC over the Pacific Coast
States and offshore from Baja. Associated cyclonic flow then will
cover nearly all the CONUS from the High Plains westward, with
height falls from the northern/central Rockies to the southern High
Plains.

At the surface, 11Z analysis showed a low over southern QC, with a
cold front southwestward across western portions of NY/PA/WV,
eastern KY, middle TN, northern MS, to east and south-central parts
of TX. The western part of this frontal zone will decelerate today,
become more diffuse, and merge with an inland-shifting, older,
marine/warm frontal zone now lying quasistationary near the LA
coastline and over deep south TX. The latter boundary will
demarcate the northern extent of optimal Gulf moisture, and should
shift northward/inland through tonight, but remain southeast of west
TX and eastern NM until day 2. Another low, with a weak cold front
arching southward over the central High Plains, will dissipate
through the period, as lee troughing intensifies just to the west
(in advance of the strengthening mid/upper trough).

...Southern High Plains...
Isolated to widely scattered thunderstorms are expected to form over
portions of far west TX and southeastern NM from late afternoon into
evening, as gradually increasing boundary-layer moisture becomes
available to diurnally heated higher terrain in the region.
Thunderstorm coverage should increase from late this evening through
the overnight hours, and begin training within a southwest/
northeast-oriented plume from far west TX to southern KS. This
convective growth will be related to strengthening low-level theta-e
and moisture, WAA-related large-scale ascent, and weakening MUCINH.
The most intense cells embedded in this regime may produce severe
hail or gusts, but the overall areal severe threat still appears to
be on the marginal side, due to lack of greater
instability/buoyancy.

In response to trough amplification aloft over the West, low-level
warm advection and moisture transport will persist and enlarge into
the southern High Plains region, with a 30-40-kt LLJ progged to
develop overnight. However this will be an early stage of the
return-flow process under modest lapse rates aloft, with
considerable residual continental trajectories still involved in low
levels, and the most-favorable, Gulf-modified parcels not forecast
to reach the region until day-2 and beyond. Though upper 50s to low
60 F surface dewpoints should spread into the Permian Basin region
of west TX and southeastern NM tonight, the area of strongest lift
farther northwest will have less moisture. MUCAPE of 500-800 J/kg
is expected around the time of most of the convective development,
increasing to the 1000-1500 J/kg range in non-convective inflow
sector by the end of the period. A layer of weaker midlevel flow
above the LLJ will restrict vertical shear, keeping effective-shear
magnitudes under 30 kt over most of the area. As such, any
supercell processes should be isolated and transient in character,
especially considering the anticipated upscale evolution to a
relatively dense convective-precip corridor.

...TX Rio Grande Valley between DRT-LRD...
Widely scattered to scattered thunderstorms should develop this
afternoon as the easterly/upslope component of flow impinges on
higher terrain of the Serranias del Burro of northern Coahuila, and
adjoining higher slopes in the direction of the Rio Grande.
Isolated large hail and damaging gusts are possible, but
predominantly on the Mexican side of the border. The boundary layer
in the valley will be strongly heated and richly moist, with
dewpoints from the upper 60s to low 70s F. Given the lack of
stronger midlevel flow, however, two related factors render a highly conditional potential on the TX side:
1. Modest deep shear, despite strong veering with height from
surface into midlevels. Forecast soundings suggest just 30-35-kt effective-shear magnitudes.
2. Uncertainty about whether orographically initiated convection
can remain organized/severe long enough to reach the border.

Early-stage supercells, if any, may not survive far enough eastward
in that mode, but outflow-dominant/forward-propagating multicellular
clusters might. As such, a very conditional severe-gust threat may
reach TX. Given the absence of a robust EML and of related MLCINH,
deep convection also may develop in the warm sector east of the Rio
Grande, amid strong diurnal heating and rich moisture, but the foci
for lift are quite unclear at this time. With all these
uncertainties, will refrain from an unconditional severe area for
this outlook cycle.

..Edwards/Mosier.. 11/01/2024

$$
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ACUS01 KWNS 011618
SWODY1
SPC AC 011617

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1117 AM CDT Fri Nov 01 2024

Valid 011630Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN HIGH PLAINS...

...SUMMARY...
Isolated severe hail and/or gusts are possible across parts of the
southern High Plains, from this evening into the overnight.

...Southern High Plains...
Visible-satellite imagery late this morning shows patches of
stratocumulus over the Pecos River Valley. This low-level moisture
coincides with the northwesterly fringe of richer moisture located
over the Hill Country and Deep South TX. The timelapse of
water-vapor imagery shows the onset of an amplifying large-scale
trough over the West. A lead lower-latitude disturbance over
northern Baja and Sonora will shift eastward along the Mexican
border during the period and aid in the development of a lee trough
over the southern High Plains beneath moderately strong
southwesterly mid-level flow.

A gradual intensification of low-level warm-air advection downstream
of the upper trough will occur through tonight across the southern
High Plains. Model guidance continues to indicate widely
spaced/isolated thunderstorms will develop late this afternoon and
into the evening across Far West TX into southeastern NM as 500-1000
J/kg MLCAPE develops coincident with the increase in low-level
moisture. Thunderstorm coverage should increase from late this
evening through the overnight hours, and begin training within a southwest/northeast-oriented plume from far west TX to southern KS.
This convective growth will be related to strengthening low-level
theta-e and moisture, WAA-related large-scale ascent, and weakening
MUCINH. The most intense cells embedded in this regime may produce
severe hail or gusts, but the overall areal severe threat still
appears to be on the marginal side, due to lack of greater instability/buoyancy.

..Smith/Moore.. 11/01/2024

$$
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ACUS01 KWNS 021248
SWODY1
SPC AC 021246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Sat Nov 02 2024

Valid 021300Z - 031200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE PERMIAN
BASIN AND SOUTH PLAINS INTO PORTIONS OF OKLAHOMA...

...SUMMARY...
Scattered strong to severe storms will be possible later today and
tonight, primarily from the Permian Basin and South Plains into
southwest Oklahoma during the late afternoon and early evening.

...Synopsis...
In mid/upper levels, a full-latitude trough is located from BC down
the West Coast States to Baja. A series of accompanying shortwaves
and speed maxima -- predominantly remaining behind the height axis
-- will contribute to the trough's eastward shift across the western
parts of the CONUS and Canada through the period. By 12Z tomorrow,
the trough should extend from the Mackenzie River Valley of
northwestern Canada, across the length of AB, to western MT, the central/eastern Great Basin, western/central AZ, Sonora, and
southern Baja. An extensive fetch of southwest flow aloft and
height falls will precede the trough over the U.S Rocky Mountains
and Great Plains.

In the slower southern part of that southwest flow, a basal
shortwave trough was evident in moisture-channel imagery over parts
of AZ and the eastern Sonora/western Chihuahua area. This feature
is augmenting the more diffuse, large-scale support from the
synoptic trough for the warm/moist advection regime and related,
extensive band of thunderstorms and precip observed from southern NM
to southern KS. This perturbation should reach eastern NM and far
west TX by 00Z, then perhaps with convective vorticity enhancement,
eject northeastward into portions of KS and western OK overnight.

At the surface, 11Z analysis showed a cold front over the Atlantic
well offshore from the Mid-Atlantic region, becoming quasistationary
across northern FL, the north-central Gulf Coast vicinity and
southeast TX, then a warm front over central/northwest TX. The
western segment of this boundary should move slowly and diffusely
northeastward today into OK as a warm front.

...Southern High Plains to portions of OK...
Scattered to numerous thunderstorms in a southwest/northeast-
oriented band should shift eastward over the outlook areas today
into this evening, offering mainly isolated damaging gusts and
marginally severe hail, with a low-end threat for embedded/QLCS
mesovortex tornadoes. Hail and tornado potential will be greatest
farther southwest today over parts of west TX and extreme
southeastern NM.

Available/modified RAOB data and objective SPC mesoanalyses indicate
effective inflow parcels already are surface-based south and west of
the effective warm front, across western OK, northwest TX, and the
South Plains to the Permian Basin. This should remain the case
throughout today, as muted diabatic heating and theta-e advection
slowly destabilize the warm sector south of the convective boundary.
This will combine with mid 60s to low 70s F surface dewpoints,
offsetting modest midlevel lapse rates enough to support
peak/preconvective MLCAPE ranging from around 2000 J/kg over
southeastern NM and the South Plains/Permian Basin regions, to
around 500 J/kg near the diffuse warm front in central OK. The
approaching synoptic and shortwave troughs will tighten height
gradients enough to boost deep shear, contributing to around
35-45-kt effective-shear magnitudes. Meanwhile, low-level
hodographs should exhibit enough size/curvature and lowest-km RH to
suggest at least marginal tornado potential.

While the parameter space (as sampled by various model soundings)
will be favorable for the full range of severe hazards in and near
the "slight risk" corridor today, a somewhat anafrontal character to
the convective band is expected, given that it will be nearly
parallel to the flow aloft and slowly progressive due to quasi-
linear outflow effects. Sustained and/or discrete supercell
potential appears greatest near the southern end of the regime over
the Permian Basin region, where instability should be greatest today
amid favorable shear, thereby relatively maximizing overall
probabilities for tornadoes and large to significant-severe (2+
inch) hail.

..Edwards/Mosier.. 11/02/2024

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ACUS01 KWNS 031250
SWODY1
SPC AC 031249

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0649 AM CST Sun Nov 03 2024

Valid 031300Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
SOUTHERN PLAINS...

...SUMMARY...
Multiple rounds of strong-severe thunderstorms are possible today
through tonight over parts of the southern Plains. Tornadoes,
damaging winds and large hail are possible.

...Synopsis...
A full-latitude, mid/upper-level trough will move slowly eastward
across the western CONUS, while evolving into a split-flow regime.
The more-influential southern section of the trough is expected to
amplify considerably as a shortwave perturbation and associated
speed max -- now located over the southern Great Basin -- pivot
through the base of the synoptic trough. By 00Z, the shortwave
trough should dig southeastward to southern AZ and adjoining
portions of Sonora. A leading vorticity lobe should eject to
eastern NM by the end of the period, within a broader area of
enhanced cyclonic flow extending across AZ, northern Chihuahua, and
west TX. A 500-mb low may form by 12Z tomorrow near the center of
that curvature, across central NM. In response to these
developments, strengthening/difluent flow and height falls will
spread eastward ahead of the synoptic trough -- across the southern
Plains and west TX.

At the surface, 11Z analysis showed an outflow boundary fronting an
MCS from the western Ozarks southwestward to northwest TX. The
boundary should shift into AR and southeastern OK through the
remainder of the morning before stalling, while the segment from the
Red River region southwestward across the Big Country and northern
Permian Basin already has become very slow-moving to stationary.
The boundary should retreat northward through the period, with
uncertainty remaining as to how far and with what specific timing,
given a substantial cold pool evident across central/western OK and
the South Plains/Panhandle region. A dryline -- initially analyzed
over southeastern NM and far west TX -- should shift eastward to the
southern Panhandle/south Plains and across the Permian Basin through
the afternoon. A surface low initially near the central CO/KS
border should move northeastward to central/north-central NE by 00Z,
with cold front southwestward to another low in southeastern CO. A
lee trough and more diffuse dryline will take shape and move
eastward across the central High Plains into western KS, before
being overtaken by the cold front.

...Southern/central Plains...
A QLCS began the period arching from the western Ozarks across
southeastern OK and parts of north-central/northwest TX. The
central/northern part of this complex is outrunning favorably
unstable inflow and should continue a broader weakening trend
through the remainder of the morning. Meanwhile the southern part
-- over southern OK and north TX -- has more buoyancy and still-
favorable vertical shear to its east and southeast. However, that
segment of convection is decelerating and non-severe. It also is
located behind the associated outflow boundary, which is exhibiting
anafrontal characteristics.

As it retreats northward across the Red River Valley today into this
evening, the outflow boundary should become more diffuse, with a
loosening baroclinic gradient. This will occur amidst broader,
synoptically driven theta-e advection. Meanwhile this feature and
the dryline to its southwest should focus additional widely
scattered to scattered thunderstorm development. Convection also
may form in the warm/moist sector east of the dryline and south of
the outflow boundary, given the lack of a substantial EML and
typically accompanying capping. With favorable low-level and deep-
layer shear expected, supercells and bowing QLCS configurations are
possible, offering all severe hazards (hail, gusts, tornadoes). The
greatest potential for relatively discrete/sustained supercells
appears to be near the retreating boundary in northwest TX and parts
of southern/central OK, and significant-severe hail may occur with
some of that convection.

Multiple convective episodes are expected from the afternoon's
greatest boundary-layer heating through late overnight, when
large-scale ascent will increase again due to both warm advection/
LLJ processes and DCVA/cooling aloft ahead of the approaching
trough. These will overlap rich low-level moisture (surface
dewpoints near and south of the boundary in the mid 60s to low 70s
F). By late overnight, airmass recovery may extend into much of
western/central OK, supporting another round of severe potential
there. A more-concentrated mesoscale-focused severe threat
(especially for tornadoes and/or severe gusts) may develop today
into this evening near the residual boundary, but uncertainty on
convective mode/coverage remains too large to assign greater
unconditional probabilities at this cycle.

Farther north, diurnally destabilized but convectively processed
trajectories will temper the overall threat into the central Plains, along/ahead of the dryline and cold front. However, a few strong-
severe thunderstorms are possible, mainly this afternoon into early
evening.

..Edwards/Mosier.. 11/03/2024

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ACUS01 KWNS 051251
SWODY1
SPC AC 051250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0650 AM CST Tue Nov 05 2024

Valid 051300Z - 061200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION
OF THE SABINE TO LOWER MISSISSIPPI VALLEYS...AND CENTRAL TO SOUTHERN WISCONSIN...

...SUMMARY...
A brief tornado or two and locally damaging winds may occur across a
portion of the Sabine to Lower Mississippi Valleys, and central to
southern Wisconsin.

...Synopsis...
Mid/upper-level longwave troughing has become well-established over
the western CONUS. That will persist through this and more outlook
periods, as a series of synoptic to large shortwave troughs
traverses the associated cyclonic-flow field. The leading such
perturbation -- now located from the central Plains south-
southwestward over the southern High Plains to far west TX -- will
eject northeastward and weaken. By 00Z, the residual, strongly
positively tilted trough should extend from a vorticity max over
western WI, across central/southwestern MO to central TX. The
perturbation will deamplify greatly overnight and accelerate to a
position near the western QC/ON border, Lake Huron and IN by 12Z.
Meanwhile, an upstream shortwave trough -- evident in moisture-
channel imagery over ID -- will dig southeastward and strengthen
greatly through the period. By 12Z, it should be oriented
northeast/southwest through a developing 500-mb low over the Four
Corners.

The 11Z surface analysis showed an elongated area of low pressure
from southern WI to northwestern MO, with cold front through central
OK and north-central/central TX. The front was preceded by an
extensive convective band and associated outflow boundary from
central IL to central AR, east TX, and deep south TX. By 00Z, the
front should catch up (or nearly so) to what remains of the
convective boundary, with the combined baroclinic zone extending
from a consolidated low over northern WI across the Mid-South region
to the northwestern Gulf shelf waters off TX. By 12Z, the front
should extend from Lower MI across western portions of KY/TN/MS to
southwestern LA and the northwestern Gulf.

...Sabine to Lower Mississippi Valleys...
The ongoing convective band, near the western edge of the "Marginal
Risk" area, should weaken overall through mid-morning. However, an
isolated damaging gust or brief tornado cannot be ruled out in the
meantime with any associated or preceding cell that may take
advantage of lingering favorable deep shear and high theta-e, in a northward-narrowing corridor.

After a relative lull of a few hours, widely scattered to scattered thunderstorms are forecast along the boundary this afternoon into
early evening, with isolated damaging gusts and/or a tornado
possible. Afternoon boundary-layer destabilization is anticipated
ahead of the convective boundary, from both fragmented/cloud-
modulated surface heating and low-level theta-e advection. A
corridor of surface dewpoints in the upper 60s to low 70s F will
persist an expand slightly northward ahead of the boundary. With no
antecedent EML and minimal MLCINH, this should offset modest
midlevel lapse rates enough to result in effectively uninhibited
buoyancy, supporting an increase in convective coverage and local
intensity this afternoon. Peak MLCAPE should range from around
500-800 J/kg over a narrow corridor of the Mid-South,
widening/increasing to around 1000-1500 J/kg over southern LA. By
contrast, lift along the boundary, and in the form of deep-layer
ascent preceding the weakening mid/upper trough, will be greater
over the Mid-South, until some nebulous point where too little
instability exists to support organized convection. The outlook has
been elongated northward somewhat to cover the marginal-buoyancy
plume near the Mississippi River.

...WI...
Isolated to widely scattered, shallow thunderstorms are possible
this afternoon, in an arc near the front and the organizing surface
low. A few cells may produce damaging gusts. A brief tornado also
may occur, especially with any cells that can linger within a narrow
zone of overlap between favorably, isallobarically backed near-
surface winds and weak boundary-layer instability. A low-confidence
and quite conditional scenario exists here, with abundant antecedent
clouds and precip likely to limit destabilization for most of the
day. Forecast soundings suggest enough large-scale ascent aloft to
cool midlevels a degree or two C, though lapse rates still will be
meager. Areas that can experience a couple hours of relatively
unimpeded heating may attain 250-500 J/kg MLCAPE.

..Edwards/Mosier.. 11/05/2024

$$
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ACUS01 KWNS 061249
SWODY1
SPC AC 061248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0648 AM CST Wed Nov 06 2024

Valid 061300Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE LOWER
FLORIDA KEYS...

...SUMMARY...
A couple of brief tornadoes will be possible within outermost
fringes of the circulation of Hurricane Rafael, from late morning
into the evening, across the Keys and the far southwestern Florida Peninsula.

...Synopsis...
In mid/upper levels, mean troughing will remain over the Rocky
Mountain States as a strong subsynoptic trough -- now evident in moisture-channel imagery over the Four Corners region -- strengthens
to a closed cyclone. The associate 500-mb low is expected to become better-developed throughout the period as it closes off and
retrogrades south-southwestward across AZ. In response to these
developments, height rises are forecast across the southern Plains
and Gulf Coast region, while ridging also builds westward from the
Bermuda high. In turn, this should shift Hurricane Rafael westward
toward the central Gulf, following today's crossing of western Cuba,
per NHC forecast.

At the surface, 11Z analysis showed a frontal-wave low over ON north
of Lake Huron, with cold front across Lower MI, IN, western parts of
KY/TN/MS, central LA, and the shelf waters off the TX Gulf Coast.
Under height rises and weakening/largely parallel flow aloft, the
frontal segment south of about I-40 should become quasistationary
through the remainder of the period. Given those factors, weak
midlevel lapse rates, and negligible mid/upper support, associated thunderstorms should have an unconditional severe potential below 5%
for gusts and less than 2% for tornado, with no large-hail threat.

...FL Keys and vicinity...
Although Rafael will be pivoting more westward away from the region
than previous forecast cycles suggested, and is a relatively small
hurricane, the influence of ambient shear imparts a northeastward
tilt to the overall convective pattern. This will lead to the
passage of peripheral cells and perhaps (over the Lower Keys)
banding features. The track forecast also should result in the
largest low-level shear remaining west and south of EYW, but
still-favorable hodographs passing across the outlook area from this
afternoon into tonight. As such, the outlook lines are shifted
slightly westward, in keeping with NHC track-forecast trends, but
still kept at 5% "slight" levels over the Lower Keys for this cycle.

See latest NHC advisories for forecast track/intensity of Rafael,
and tropical-related watches/warnings.

..Edwards/Mosier.. 11/06/2024

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ACUS01 KWNS 071250
SWODY1
SPC AC 071248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0648 AM CST Thu Nov 07 2024

Valid 071300Z - 081200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WEST TEXAS...

...SUMMARY...
Large hail, isolated severe thunderstorm gusts, and a tornado or two
are possible this evening and tonight across parts of west Texas.

...Synopsis...
A closed and temporarily cut-off, mid/upper-level cyclone was
drifting eastward to southeastward over the Desert Southwest and
Four Corners regions, and centered near INW. A large, well-
developed, baroclinic-leaf formation was apparent in IR and
moisture-channel imagery in its eastern semicircle, across much of
NM and CO, and extending across the central High Plains. The 500-mb
low is forecast to move slowly to central NM through the period,
while a shortwave trough now north of the low pivots around the southern/southeaster side of the cyclone tonight. Associated height
falls and large-scale ascent will gradually overspread west TX and
the southern High Plains, both in the form of DCVA nearer to the
cyclone core, and warm advection over much of the southern Plains to
its east.

Meanwhile, per latest NHC forecasts, Hurricane Rafael will continue
to move westward away from the Keys and Cuba, toward the central/
south-central Gulf. This will occur south of an arc of mid/upper
ridging extending from the subtropical Atlantic across FL and the
north-central to southwestern Gulf.

At the surface, the key feature for today's forecast will be a cold
front -- drawn at 11Z from the Ohio Valley across central AR, to
near a TXK-ERV line and becoming stationary to warm westward to a
low near the Rio Grande, south of 6R6. Another low was drawn
between MAF-FST, and warm frontogenesis apparent to its east-
southeast likely will persist and result in effective northward
displacement of the western segment of the main frontal zone with
time today. As the aforementioned shortwave trough pivots toward
the region, surface cyclogenesis is expected over the lower Pecos Valley/Permian Basin region of west TX, consolidating the previously
elongated, multi-centered low-pressure area. The low should move
northward or north-northeastward tonight, toward the Caprock region
of northwest TX, with a cold front to its south extending to the Big
Bend region. Meanwhile, the warm-frontal segment should advance
northward over west-central TX, though considerable mesoscale
uncertainty remains as to how far, given:
1. The strength of the ambient continental/polar airmass to its
north and
2. Probable reinforcement by convection/precip on the cool side
much of today.

...West and central TX...
Predominantly elevated thunderstorms are expected to develop today
and gradually increase in coverage while moving northward over
central and northwest TX, in a weakly capped plume of strengthening
warm advection, moisture transport and ascent to LFC. Isolated
severe hail is possible with this activity, though lack of
substantial buoyancy should limit overall severe potential to
marginal in coverage and intensity.

As that process continues, a diurnally heated slot of return-flow boundary-layer air, containing increasingly unstable, surface-based
parcels, will spread from south-central TX, the Rio Grande Valley
and the southern Hill Country northwestward toward the frontal and
cyclogenetic regimes. Diurnal heating and moist advection are
expected to yield favorable warm-sector destabilization. Surface
dewpoints increasing into the low 60s F in northern areas and upper
60s to near 70 F over southern parts of the outlook will yield peak/preconvective MLCAPE in the 1500-2000 J/kg range ahead of the
cold front and south of about I-20, with sharp reductions across the
front toward the upper cyclone, and northward into the ambient
rain-cooled airmass.

Meanwhile, large-scale ascent will continue to increase gradually on
both sides of the front, peaking late overnight. These processes
will support isolated to scattered thunderstorm development from
late afternoon into tonight, along the front and over higher terrain
in the Big Bend region. Some of this activity may be supercellular
for a few hours, with all severe hazards possible. Forecast
hodographs indicate some tornado potential, especially near the low
and if a discrete storm can interact with a favorably aligned
segment of the front while maintaining warm-sector surface inflow. Aforementioned mesoscale uncertainties preclude a more-focused,
unconditional 5% tornado area at this time. The delay in the
strongest forcing for ascent after the peak buoyancy and the
potential for evolution to extensively messy modes also renders
tornado potential quite conditional. Convective coverage overall
should increase to scattered/numerous, expand to both sides of the
front as cooling aloft overspreads the region, and render much
messier convective mode. Large hail will be possible on either side
of the front, especially with relatively sustained/discrete cells,
and damaging gusts will be most probable with convection moving
into/through the warm sector.

..Edwards/Mosier.. 11/07/2024

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ACUS01 KWNS 081254
SWODY1
SPC AC 081252

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0652 AM CST Fri Nov 08 2024

Valid 081300Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER NORTH-CENTRAL TEXAS...

...SUMMARY...
Severe-thunderstorm threat exists from north Texas to the Hill
Country and parts of central/east Texas through this evening. The
most focused tornado, damaging-wind and hail potential appears to be
over north-central Texas.

...Synopsis...
The mid/upper-level pattern features a closed, temporarily cut-off, synoptic-scale cyclone, initially centered over central NM. As a
strong, basal shortwave trough pivots northeastward across eastern
NM and the TX Panhandle today, the 500-mb low will shift east-
northeastward toward CAO by 00Z. Overnight, the low should track north-northeastward, reaching the GLD vicinity by 12Z. Height falls
should occur over central/north TX today, then becoming neutral to
slightly rising overnight.

The 11Z surface analysis showed a frontal-wave low near SWW, with a
cold front south-southwestward between DRT-6R6. A warm front was
drawn from the low through some rain-cooled air to near MWL, then east-southeastward over southern fringes of the Metroplex to between
LFK-ESF. The low is expected to move northward to near the
northeastern corner of the TX Panhandle by 00Z and occlude, while
the occluded/cold front reaches western OK, north-central/central
TX, to near LRD. The warm front should drift northward over north- central/northeast TX, with its progress slowed by increasing
precip/convection to its north. By 12Z tomorrow, the low should get
stacked with the 500-mb center over northwestern KS, with the cold
front reaching east TX and the shelf waters off the TX Gulf Coast.

Meanwhile, Hurricane Rafael is forecast to remain well-removed from
land this period, moving generally westward over the central to
west-central Gulf then slowing/meandering after this period. See
NHC advisories for latest forecast track/intensity info on Rafael.

...North to central TX...
An ongoing area of convection over parts of north TX and southern OK
is expected to shift northward over increasingly elevated and less-
unstable inflow parcels and weaken through midday. Meanwhile,
closer to the cold front, scattered thunderstorms are expected to
develop over the next several hours through early afternoon,
evolving into a nearly solid convective band with embedded
supercells and bow/LEWP formations possible. This activity should
shift eastward over central and north TX through early evening,
offering at least marginal potential for all severe hazards.

Meanwhile, isolated to scattered thunderstorms are possible in the
warm sector and along/north of the warm front. This activity should
move northward to northeastward. Any sustained, relatively discrete
cells with prolonged access to surface-based parcels in the warm
sector, and especially interacting with the warm front, may rotate
with a threat for all hazards (hail, damaging to severe gusts and
mesoscale peak in tornado potential) also present. The associated theta-e/instability gradient is expected to align northwest/
southeast very near or even across the DFW Metroplex. This will
yield an increased severe threat from north to south into more-
unstable inflow air, and within the southern part of the relatively high-vorticity gradient itself. Given the superposition of these
foci and the expected favorable parameter space, the north-central
TX part of the outlook is being upgraded for all hazards this cycle.

Upper 60s to low 70s F surface dewpoints already are present in the
warm sector, and will shift north slowly, in step with the warm
front, before the main north-south band overtakes the region. This
should occur during the afternoon when low-level, warm-sector
instability is maximized away from convection. Despite modest lapse
rates aloft (manifest in mid/upper-level stable layers sampled by
the 12Z FWD sounding), a northwestward-narrowing, triangular
corridor of 1000-1500 J/kg peak MLCAPE is expected. Veering winds
with height are forecast to continue, with hodograph curvature/size
largest along the warm front, and enough deep shear (effective-shear
magnitudes 35-45 kt in central/north TX, weakening southward and
eastward) to support occasional supercell structures. Overnight,
supportive large-scale ascent and the elevated LLJ each should shift
northward away from the area, while the main band of convective-
scale forcing shifts into east TX and weakens.

..Edwards/Bentley.. 11/08/2024

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ACUS01 KWNS 091226
SWODY1
SPC AC 091224

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0624 AM CST Sat Nov 09 2024

Valid 091300Z - 101200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected over the conterminous U.S.
through tonight.

...Synopsis/Discussion...
The mid/upper-level pattern across the CONUS will lose amplitude
through the period, as a synoptic-scale cyclone now centered near
GLD weakens, ejects northeastward, and rejoins the prevailing
westerlies. The associated 500-mb low should reach central NE by
00Z, then across northwestern IA by 12Z tomorrow. Meanwhile, the
NHC forecasts Hurricane Rafael to move slowly west-northwest across
the west-central Gulf through tonight, remaining far from land,
while weakening due to deep shear and dry-air involvement.

In between, a plume of partly modified return-flow air, marginally moist/unstable for deep convection, will support isolated to widely
scattered thunderstorms in a broad swath from the TX/LA Gulf Coast
to parts of IA/IN and much of IL. Effective inflow to convection in
this swath should be elevated over the mid Mississippi Valley and
similar latitudes, where deep shear is greatest. As shear weakens
with southward extent from the Mid-South to the coast, especially
south of a warm front now over north-central LA, surface-based
parcels amid weak lapse rates will prevail. By afternoon, the warm
front will angle northward into parts of eastern AR, and MLCAPE
should range from around 500 J/kg over the Mid-South to near 1000
J/kg just inland from the coast. Organized severe potential will be
stunted by lack of stronger lift and shear where buoyancy is
sufficient.

..Edwards/Bentley.. 11/09/2024

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ACUS01 KWNS 101228
SWODY1
SPC AC 101226

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0626 AM CST Sun Nov 10 2024

Valid 101300Z - 111200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The risk for severe thunderstorms appears minimal through tonight.

...Synopsis...
General upper-air pattern deamplification is expected over most of
the CONUS through the period, except over:
1. The West Coast (height falls ahead of an approaching,
high-amplitude synoptic trough) and
2. The Great Lakes (height falls preceding the ejection of the
cyclone now centered over northwest IA). The formerly
cut-off/larger cyclone is rejoining the prevailing westerlies, and
will accelerate eastward and weaken over the Great Lakes. This will
happen as a strong shortwave trough -- evident in moisture-channel
imagery over eastern/southern AB -- digs east-southeastward toward
Lake Superior by 12Z tomorrow, while forming a closed or nearly
closed 500-mb low.

Meanwhile, Tropical Storm Rafael continues to weaken as its low-
level center and deep convection get more displaced from each other,
per NHC discussions. The circulation is forecast to continue
weakening, as the low-level vortex loops around the central/west-
central Gulf today, then shift southwestward thereafter. Refer to
NHC advisories for latest forecast track/intensity of Rafael.

In between those features, a plume of moist low-level air, cooling
northward at the surface and aloft, will support isolated to
scattered thunderstorms, near and east of an occluded/cold frontal
zone drawn at 11Z from southern IL across westernmost portions of
KY/TN, western MS, central/southwestern LA, and TX coastal waters.

...Gulf Coast to Ohio Valley...
Overall severe potential will be limited by lack of stronger shear
in the south (closer to the coast) where low-level theta-e is
largest, and lack of surface-based instability in the north. Some
model soundings suggest that surface-based parcels and marginal deep
shear (effective-shear magnitudes in the 30-40-kt range) may overlap
this afternoon over portions of the Tennessee Valley to lower Ohio
Valley. While this will need to be monitored, lack of backing in
low-level flow will limit both convergence and hodograph size, amid
weak deep-layer lapse rates and potentially messy convective mode.
At this time, the severe threat appears too low and conditional for
an outlook area.

..Edwards/Bentley.. 11/10/2024

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ACUS01 KWNS 110521
SWODY1
SPC AC 110520

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1120 PM CST Sun Nov 10 2024

Valid 111200Z - 121200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
The risk for severe thunderstorms appears negligible across the U.S.
today through tonight.

...Synopsis...
Models indicate that a modestly amplified wave within the
mid-latitude westerlies across the eastern Pacific will split while
progressing inland of the Pacific coast during this period. One
emerging smaller-scale perturbation is forecast to contribute to
cyclogenesis to the lee of the Canadian Rockies, while another
impulse digs inland across the Sierra Nevada into the southern Great
Basin by late tonight. In lower-levels a cold front may precede the
trailing short wave through much of the West, advancing into the
Southwest and approaching the southern Rockies by daybreak Tuesday.

As downstream ridging develops eastward through interior North
America, it appears that mid-level troughing will amplify to its
east, as one notable embedded short wave digs across the lower Great
Lakes vicinity through the northern Atlantic Seaboard. This is
forecast to be accompanied by a reinforcing cold intrusion southeast
of the Upper Midwest through much of the Northeast, Ohio and
Missouri Valleys. A preceding front is likely to advance through
much of the southern Mid Atlantic, while stalling/weakening over the
Gulf Coast states.

...Southeast...
In advance of the lead cold front, models suggest that a mid-level
perturbation will be in the process of accelerating east of the
southern Appalachians by 12Z this morning. It appears that forcing
for ascent may be accompanied by some risk for thunderstorm
development near the coastal Carolinas at the outset of the period.
However, guidance suggests that the more substantive destabilization
and higher probabilities for thunderstorm initiation will generally
focus offshore of coastal areas during the mid to late morning.

...Pacific Northwest into northern Sierra Nevada...
Beneath a tongue of relatively cool mid-level air (-26 to -28C
around 500 mb) forecast to spread inland of the coast during the
day, destabilization may become sufficient to support convection
capable of producing lightning across coastal Washington/Oregon into
the western slopes of the Cascades, and perhaps along the western
slopes of the Sierra Nevada.

..Kerr/Thornton.. 11/11/2024

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ACUS01 KWNS 121254
SWODY1
SPC AC 121252

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0652 AM CST Tue Nov 12 2024

Valid 121300Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN HIGH PLAINS...

...SUMMARY...
Isolated strong to severe thunderstorms may impact parts of the
Texas South Plains and Oklahoma/Texas Panhandle vicinity this
evening, perhaps accompanied by some risk for hail and gusty winds.

...Southern High Plains...
An upper trough over the Great Basin will advance eastward across
the Rockies today, reaching the Plains late tonight into early
Wednesday morning. Large-scale ascent preceding this feature will
encourage modest surface cyclogenesis across parts of the
northern/central High Plains. Low-level moisture will return
northward today over portions of the southern High Plains, although
its depth and quality will remain limited. It appears unlikely that
convection will develop this afternoon across northwest TX into the
OK/TX Panhandles, as a cap and weak instability should inhibit
initiation.

A somewhat better opportunity for thunderstorms will exist this
evening across this area, mainly around/after 00-04Z, as warm
advection and lift associated with a strengthening low-level jet
increases, and as a surface cold front overtakes the lee trough.
While MUCAPE is expected to remain rather weak (generally 500-1000
J/kg or less), strong deep-layer shear will support organized
updrafts with any sustained convection. Isolated hail appears to be
the main threat, as thunderstorms should have a tendency to remain
slightly elevated. But, some chance for strong/gusty winds may also
exist. The window for severe hail should remain small in space and
time this evening, as convection will likely grow upscale fairly
quickly. Even so, small hail may occur farther north/east into parts
of KS and OK overnight into early Wednesday morning.

..Gleason/Bentley.. 11/12/2024

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ACUS01 KWNS 131300
SWODY1
SPC AC 131258

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0658 AM CST Wed Nov 13 2024

Valid 131300Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE LOWER MISSISSIPPI VALLEY AND COASTAL PACIFIC NORTHWEST...

...SUMMARY...
A few strong to severe thunderstorms may occur today across the
lower Mississippi Valley, posing a risk for isolated severe gusts
and perhaps a tornado or two. Occasional severe winds may also
develop along parts of the coastal Pacific Northwest.

...Lower Mississippi Valley...
Rich low-level moisture will continue to stream northward today
across parts of the lower MS Valley into the Mid-South as an upper
trough over the Plains continues eastward towards the OH Valley.
Primary surface low and better forcing associated with this upper
trough are forecast to remain well north of the inland-advancing
warm sector. Even so, scattered surface-based thunderstorms should
develop by this afternoon as a remnant/weak surface low off the LA
Coast moves slowly inland. Filtered daytime heating of the moist
low-level airmass should result in modest instability developing by
this afternoon, even though mid-level lapse rates will remain poor
(see 12Z JAN/LIX soundings). Low-level southerly flow will not be
overly strong across the lower MS Valley, but gradual veering and
strengthening of winds with height through mid levels should support
sufficient deep-layer shear for modest updraft organization.

A few marginal supercells/clusters may pose an isolated threat for
strong to damaging winds as they spread eastward across LA/MS this
afternoon and evening. Enough low-level shear should also be present
to foster some updraft rotation and the threat for a tornado or two,
with an isolated severe threat potentially continuing into tonight
across parts of southwest AL and vicinity. The warm sector will
become increasingly pinched off with northward extent in MS and
western TN, with convection generally expected to outpace the
low-level moisture return. Given the expected mismatch of stronger forcing/shear farther north and better instability to the south,
have opted to maintain the Marginal Risk this update, with some
expansion based on latest guidance trends.

...Coastal Pacific Northwest...
Cold mid-level temperatures (around -24 to -26C at 500 mb) and
modestly steepened mid-level lapse rates associated with an
eastward-moving upper trough will help support weak instability
today across parts of the coastal Pacific Northwest (reference 12Z
UIL sounding). Persistent large-scale ascent across this region will
support both low-topped cells and bands of convection moving
eastward through this afternoon and early evening. Given the
forecast strength of the low-level winds, some of this activity may occasionally produce strong to severe wind gusts, and perhaps small
hail. Tornado potential remains unclear, as low-level flow will have
a tendency to veer more to southwesterly through the day, which
should limit 0-1 km SRH.

..Gleason/Bentley.. 11/13/2024

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ACUS01 KWNS 141251
SWODY1
SPC AC 141250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0650 AM CST Thu Nov 14 2024

Valid 141300Z - 151200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
COASTAL NORTH CAROLINA...

...SUMMARY...
Isolated strong to severe thunderstorms posing a risk for gusty
winds and perhaps a tornado may occur across parts of coastal North
Carolina this evening/tonight.

...Coastal Carolinas...
A pronounced upper trough will continue eastward today from the
OH/TN Valleys and Midwest towards the southern Mid-Atlantic. As this
occurs, a weak surface/coastal low will develop in response across
the eastern Carolinas this afternoon/evening and adjacent coastal
waters tonight. Most guidance suggests this surface low will remain
very near/along the immediate coast, or just offshore. Recent RAP
runs are a notable exception, showing a slightly more inland track.
Regardless, sufficient low-level moisture and related weak
boundary-layer instability should be present by this evening across
parts of coastal NC and the Outer Banks. Any surface-based
convection that can be sustained tonight in the favorably sheared
environment may pose an isolated threat for strong to severe wind
gusts, and perhaps a tornado. Greater severe potential remains
evident just offshore and over the Gulf Stream, but there still
appears to be enough severe potential over land to maintain the
Marginal Risk with this update.

..Gleason/Bentley.. 11/14/2024

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ACUS01 KWNS 251954
SWODY1
SPC AC 251952

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Fri Oct 25 2024

Valid 252000Z - 261200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...20Z Update...
Minor changes were made to the general thunderstorm forecast based
on current observations and recent model guidance. See the previous
discussion for additional details.

..Wendt.. 10/25/2024

.PREV DISCUSSION... /ISSUED 1100 AM CDT Fri Oct 25 2024/

...Synopsis and Discussion...
A modestly amplified and progressive large-scale pattern will
persist over the CONUS today, including the deamplification of an eastward-moving shortwave trough over the Midwest/OH Valley. A
surface cold front will similarly continue east-southeastward across
the OH Valley/Mid-South toward the Appalachians and TN Valley
through tonight. Isolated thunderstorms should continue this
afternoon across the Ozarks near the cold front, and also
northeastward into IN/OH to the north of a warm front across the
lower OH Valley. Weak/thin buoyancy and meager effective shear
within the more unstable warm sector are expected to limit severe
thunderstorm potential through the period. Occasional lightning
flashes may also occur across parts of the U.P. in MI and adjacent
Lake Superior this evening/tonight as cold mid-level temperatures
associated with an upper trough support weak instability.

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ACUS01 KWNS 260539
SWODY1
SPC AC 260537

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1237 AM CDT Sat Oct 26 2024

Valid 261200Z - 271200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Little thunderstorm activity is forecast across the contiguous
states; however, an isolated weak thunderstorm cannot be ruled out
near the ArkLaTex, and across the southern Appalachians.

...Discussion...

Large-scale pattern remains seasonally tranquil with mean upper
ridging holding across the Rockies and a broader trough noted across
the eastern US. This flow regime ensures richer moisture/instability
will remain suppressed across lower latitudes as northwesterly flow
aloft dominates much of the country east of the Rockies.

Deep northwesterly flow will encourage a surface high to settle
across the Midwest and the leading edge of this air mass will extend
into the southern Appalachians-mid South-Arklatex. Latest model
guidance suggests a surface front will arc from western NC-northern MS-northeast TX by 18z. Boundary-layer heating will be prominent
across the southern Arklatex and from northern AL into SC. As a
result, weak buoyancy will develop in both of these regions. With
higher PWs noted along this corridor, forecast soundings suggest
some potential for lightning discharge in the deepest updrafts. Even
so, convection is expected to remain rather sparse, and likely
concentrated in the afternoon into early-evening hours.

..Darrow/Lyons.. 10/26/2024

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ACUS01 KWNS 271927
SWODY1
SPC AC 271926

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0226 PM CDT Sun Oct 27 2024

Valid 272000Z - 281200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today and tonight.

...20Z Update...
No changes were needed with this update. See the previous discussion
below for details.

..Weinman.. 10/27/2024

.PREV DISCUSSION... /ISSUED 1105 AM CDT Sun Oct 27 2024/

...Synopsis and Discussion...
Strong height falls will occur across the Pacific Northwest today as
a shortwave trough moves eastward over this region. Cooling
temperatures aloft will encourage steepening mid-level lapse rates
as thermodynamic profiles gradually become favorable for isolated
weak convection. Various NAM/RAP forecast soundings suggest parcels
could attain heights necessary for occasional lighting discharge by
late this morning into the afternoon, with continued thunderstorm
potential this evening and overnight.

Convection along/near a surface front in southeast AR and northern
MS will remain capable of producing isolated lightning in the short
term given the presence of weak MUCAPE. Even though large-scale
ascent will remain weak, additional thunderstorms may develop this
afternoon farther south along/near the front as daytime heating
occurs across parts of the ArkLaTex.

A low-amplitude shortwave trough will spread southeastward across
the southern Appalachians during the late afternoon. Based on where
a surface front is currently located, this feature should support
convection generally remaining off the SC Coast, where low-level
convergence and instability will be maximized over the Gulf Stream.

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ACUS01 KWNS 231222
SWODY1
SPC AC 231221

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0721 AM CDT Wed Oct 23 2024

Valid 231300Z - 241200Z

...NO THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms are unlikely through tonight.

...Upper OH Valley into western NY this evening...
A midlevel shortwave trough over the upper MS Valley this morning
will progress east-southeastward to NY/PA and the Mid-Atlantic by
the end of the period. Ascent preceding the midlevel trough and an
associated surface cold front could support some shallow convective
showers late this afternoon/evening from northeast OH to western NY.
However, marginal low-level moisture and minimal buoyancy suggest
that thunderstorms are unlikely.

...Northern AR to central OK this afternoon...
Boundary-layer dewpoints near 60 F and surface heating will drive
surface-based buoyancy this afternoon along a slow-moving front from
northern AR into central OK. Thermodynamic profiles suggest some
potential for deep convection, but forcing for ascent will remain
shallow/weak at best. Overall, thunderstorm potential appears too
limited for an outlook area.

..Thompson/Goss.. 10/23/2024

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ACUS01 KWNS 251230
SWODY1
SPC AC 251228

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0728 AM CDT Fri Oct 25 2024

Valid 251300Z - 261200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Discussion...
A modestly amplified/progressive large-scale pattern will persist
over the CONUS, including the deamplification of an eastward-moving
shortwave trough over the Midwest/Ohio Valley. A cold front will
similarly continue east-southeastward across the Ohio
Valley/Mid-South toward the Appalachians and Tennessee Valley
through tonight. Widely scattered thunderstorms are ongoing this
morning across the Ozarks near the cold front, and also
northeastward into Indiana and Ohio to the north of a warm front
across the Lower Ohio Valley. A modest increase in thunderstorm
coverage should regionally occur into the afternoon, but weak/thin
buoyancy and meager effective shear within the more unstable warm
sector are expected to limit severe thunderstorm potential.

..Guyer/Goss.. 10/25/2024

$$
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ACUS01 KWNS 211247
SWODY1
SPC AC 211246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Mon Oct 21 2024

Valid 211300Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATER THIS
AFTERNOON/EVENING FOR CENTRAL KS INTO SOUTH CENTRAL NE...

...SUMMARY...
A few severe thunderstorms with large hail are possible across parts
of central Kansas into south central Nebraska, mainly from mid
afternoon to early evening.

...Central Plains through this evening...
A midlevel low over CO this morning will continue to evolve into an
open wave while progressing eastward over KS/NE today to IA/MO
overnight. Largely elevated convection is ongoing this morning in a
broken band from the TX Panhandle into western KS, in the zone of
ascent preceding the midlevel trough. Isolated, marginally severe
hail and gusty outflow winds will be possible this morning with
these storms, given MUCAPE up to 1000 J/kg and midlevel lapse rates
near 7.5 C/km. In the wake of the morning convection, a narrow
corridor of low-level moisture (boundary-layer dewpoints in the 50s)
and surface heating will precede the midlevel trough and an
associated lee surface trough from the eastern TX Panhandle into
western and central KS/NE.

A few thunderstorms will be possible along/immediately east of the
lee trough by mid-late afternoon this afternoon as convective
inhibition diminishes with at least weak ascent. Forecast profiles
suggest the potential for isolated supercells capable of producing
large hail (1-1.75 inches in diameter), isolated strong outflow
gusts of 50-60 mph, and potentially a tornado or two. The severe
threat will peak late this afternoon before decreasing near/after
sunset as the low levels begin to stabilize and the zone of ascent
shifts east of the confined moist sector.

..Thompson/Goss.. 10/21/2024

$$
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ACUS01 KWNS 221128
SWODY1
SPC AC 221126

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0626 AM CDT Tue Oct 22 2024

Valid 221300Z - 231200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today through tonight.

...Synopsis...
A midlevel shortwave trough over IA/MO will continue eastward toward
Lower MI/IN/OH and lose amplitude, while phasing gradually with an
upstream trough now over MT. Isolated, elevated thunderstorms will
be possible this morning across the middle MS Valley in the zone of
ascent. Weak buoyancy and ascent will come out of phase by later
this afternoon into tonight, when the threat for thunderstorms will
diminish. Farther north, weak convection and isolated lightning
flashes may occur across northeast MN in a band of ascent and
minimal buoyancy along a cold front this afternoon/evening.

Elsewhere, lingering low-level moisture, a subtle midlevel trough,
and surface heating over higher terrain could support isolated
thunderstorms this afternoon over the Davis Mountains in southwest
TX.

..Thompson/Goss.. 10/22/2024

$$
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ACUS01 KWNS 181253
SWODY1
SPC AC 181251

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0751 AM CDT Fri Oct 18 2024

Valid 181300Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE SOUTHERN ROCKIES AND SOUTHERN HIGH PLAINS...

...SUMMARY...
Isolated severe hail, damaging gusts and a tornado or two will be
possible this afternoon and evening over parts of the southern
Rockies and southern High Plains.

...Synopsis...
In mid/upper levels, a heretofore progressive and high-amplitude
pattern will slow down temporarily, across the western half of the
CONUS. A strong trough is apparent in moisture-channel imagery from
the northern Rockies south-southwestward across the Great Basin to
near the lower Colorado River Valley. A 500-mb low is forming along
the trough in NV -- and will deepen through the period while
anchoring an increasingly pronounced and slower-moving cyclone. By
00Z, the low should be over central AZ between FLG-PHX, then wobble
erratically over the same area through the remainder of the period.

At 11Z, the surface analysis showed a cold front from northwestern
MN, through a low between PIR-HON, then southwestward to another low
near AKO and into central CO. This front should shift slowly
southeastward through the period, to a position from northeastern MN
to northeastern NE to near RTN by 12Z. There it should connect to
another cold front now analyzed from a surface low over southeastern
UT, southwestward across northern/southwestern AZ. The western
front should move east-southeastward into central NM tonight, then
decelerate in step with the associated mid/upper cyclone. A vast,
continental anticyclone surrounds a high analyzed over western PA,
and covers most of the CONUS from the Mississippi Valley eastward,
with ridging southwestward across south TX. The high should remain
over the interior Mid-Atlantic region through the period, while
ridging persists southwestward through south TX.

...Southern Rockies/High Plains region...
A band of convection -- now producing considerable lighting from
southeastern UT into northern AZ -- should persist through much of
the period and shift eastward-southeastward, reaching from the San
Juan Mountains of southwestern CO across much of western NM between
00Z-03Z this evening. While isolated strong gusts or small hail may
occur with this partly frontally forced activity, very limited
buoyancy should preclude an organized severe threat. Farther east,
isolated to widely scattered thunderstorms should form in the warm
sector this afternoon, over and near the ranges from the Guadalupe
Mountains northward to the east side of the Sangre de Cristos.
Convection also may develop over adjoining Plains, given diurnal
heating in a weakly capped setting that lacks an antecedent EML.
Some of this activity may become supercellular amidst increasing
deep shear, with isolated damaging gusts and severe hail possible.
Tornado potential still appears marginal.

A host of mostly offsetting factors continue in the forecast
environment in and near the outlook area today, keeping the
unconditional severe probabilities in the marginal range for this
cycle. Thermodynamically, the immobility and intensity of the
low-level anticyclone over the East will limit favorable moisture to
a narrow, only partially Gulf-modified return-flow corridor through
the period. 50s F surface dewpoints -- already common at lower
elevations in eastern NM, should mix into the 40s F where diurnal
heating is most sustained today over the Plains. Upper 40s to lower
50s dewpoints may persist farther northwest under more persistently
cloudy areas, leading to greater RH and lower LCL, but amid cooler
surface temperatures. However, at higher elevations, this still may
support surface-based effective-inflow parcels. With the coolest
midlevel temperatures and strongest DCVA aloft lagging closer to the
cyclone core, and mostly behind the low-level cold front, poor
midlevel lapse rates will limit buoyancy over the region. This, and
lack of richer moisture, should keep MLCAPE generally in the 300-800
J/kg range -- and highly variable depending on elevation and patchy heating/mixing.

Vertical shear amid southwest flow aloft will strengthen through the
evening along/ahead of the western frontal zone as the cyclone digs
into AZ. Enlarging hodographs and low-level shear will accompany a strengthening low-level jet and greater moisture this evening and
tonight over much of eastern NM, along/ahead of the slow-moving
frontal convective arc. However, this also will coincide with
nocturnal boundary-layer stabilization and likely an increasingly
messy convective mode. A window of tornado potential may exist from
late afternoon into early evening during that transition, especially
at higher elevations of the Plains/mesa country, but still appears
too isolated and conditional for more than marginal probabilities.

..Edwards/Goss.. 10/18/2024

$$
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ACUS01 KWNS 151242
SWODY1
SPC AC 151241

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 AM CDT Tue Oct 15 2024

Valid 151300Z - 161200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Synopsis/Discussion...
A highly amplified mid/upper-level pattern will persist over the
CONUS, characterized by an elongated cyclone over the Great Lakes
and Northeast, with a primary center initially over the lower St.
Lawrence River region. The associated 500-mb low should drift
erratically near its present location for most of today, then move northeastward toward the easternmost extension of QC overnight. A
strong, basal trough was evident in moisture-channel imagery over
the Lower Great Lakes and southern Upper Great Lakes region,
westward across the upper Mississippi Valley. This trough will
pivot southeastward through the period, then by 12Z tomorrow, extend
from offshore of New England across VA, the western Carolinas,
northern GA, to central MS and the Arklatex region. Associated cold
air aloft, steep low/middle-level lapse rates (aided by
boundary-layer flow off the relatively warm lakes) and weak moisture
will foster isolated thunderstorm potential south of portions of
Lakes Erie and Michigan today.

Elsewhere, thunderstorms have persisted all night in a residual, quasistationary, convectively reinforced baroclinic zone draped
across the Bahamas and southern/western Straits of FL. This thunder
potential should persist episodically through the period, with some
inland development possible this afternoon across the Everglades and
perhaps adjoining southern parts of metro South FL. A stronger
boundary, moving southward through northern/central FL as a cold
front, may support isolated thunder near that part of the FL East
Coast today, amid modest moisture/lift. In the Four Corners region,
isolated to widely scattered, high-based thunderstorms are expected
this afternoon as heating/mixing reduce generally 30s F surface
dewpoints into the 20s, but still just enough moisture to support
weak (generally less than 200 J/kg) peak MLCAPE.

..Edwards.. 10/15/2024

$$
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ACUS01 KWNS 161214
SWODY1
SPC AC 161213

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0713 AM CDT Wed Oct 16 2024

Valid 161300Z - 171200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms are not currently expected on Wednesday.

...Synopsis/Discussion...
In mid/upper levels, a highly amplified, yet still quite progressive
pattern will persist through the period over the CONUS. A leading
synoptic trough was initially positioned from a low near Anticosti
Island in the Gulf of St. Lawrence, southwestward across New
England, the near-coastal Mid-Atlantic region, and the southern
Appalachians, to parts of AR and eastern OK. The southern
Appalachian part of the trough is expected to consolidate into a
closed cyclone as it moves eastward across the Carolinas and VA,
with a well-defined 500-mb low expected over the Outer Banks
vicinity by 12Z tomorrow. However, associated surface frontal-wave cyclogenesis and related elevated thunder potential in the wrapping
conveyor both should remain offshore. The trailing cold front --
analyzed at 11Z from central FL across the north-central Gulf to
near CRP and across south-central TX -- will support isolated
thunderstorm potential today over parts of south FL and deep south
TX before moving south of both areas.

Meanwhile, a synoptic-scale trough -- with several embedded small shortwaves/vorticity lobes -- is apparent in moisture-channel
imagery from the AK Panhandle south-southeastward, just offshore of
and parallel to the CONUS Pacific Coast. As these features move
ashore today, preceded by several other vorticity lobes, height
falls and colder air aloft will spread inland, steepening midlevel
lapse rates atop marginal low/middle-level moisture over parts of
the Pacific Northwest and a broad area of the Intermountain West/
Great Basin, with low-level warm advection and diabatic heating also
aiding instability in the interior swath. Isolated thunderstorms
should result.

..Edwards/Goss.. 10/16/2024

$$
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ACUS01 KWNS 171233
SWODY1
SPC AC 171231

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0731 AM CDT Thu Oct 17 2024

Valid 171300Z - 181200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Organized severe thunderstorms are not expected through tonight.

...Synopsis...
In mid/upper levels, a highly amplified yet progressive pattern will
persist through the period, as a strong, synoptic-scale ridge shifts
eastward over the Great Lakes, and the Mississippi/Ohio/Tennessee
Valleys. Upstream, a strong trough now near the coastal Pacific
Northwest will dig southeastward across interior parts of the West
Coast States today into this evening, and much of the western Great Basin/Intermountain regions overnight. By 12Z, a 500-mb low should
form over eastern NV, along a trough extending from the northern
Rockies to the lower Colorado River Valley. As that occurs, a
weaker, shortwave trough -- evident in moisture-channel imagery near
the NV/UT and CA/AZ borders, should eject northeastward over the
central Rockies and central/northern High Plains, while weakening.
By the end of the period, broadly cyclonic flow will cover most of
the western CONUS.

Ahead of the strengthening main (Pacific Northwest) trough, height
falls and areas of DCVA/cooling aloft are forecast. Those will
overlie a southeastward-surging low-level cold front across the
Intermountain region, and support isolated to widely scattered
thunderstorm potential over a vast swath of the West, either side of
the front. Meager but sufficient low/midlevel moisture -- mostly
with distant/indirect origins in the subtropical gulfs either side
of northern Mexico -- will support this convection. Strong gusts
may accompany some of the afternoon and early evening activity
along/ahead of the cold front across northern parts of NV/UT, amidst strengthening deep shear. However, overall moisture/buoyancy appear
too meager to outline an unconditional severe area at this time.

..Edwards/Goss.. 10/17/2024

$$
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ACUS01 KWNS 131247
SWODY1
SPC AC 131246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Sun Oct 13 2024

Valid 131300Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL/SOUTHERN APPALACHIANS AND TENNESSEE VALLEY...

...SUMMARY...
Strong to locally severe thunderstorms are possible, mainly this
evening, across parts of the central/southern Appalachians and
Tennessee Valley. Isolated wind damage and marginally severe hail
should be the main threats.

...Central/Southern Appalachians into the Tennessee Valley...
Ongoing elevated thunderstorms across northeast OH and western PA
should continue eastward this morning in tandem with an enhanced west-southwesterly low-level jet. This activity is expected to
outpace low-level moisture return and related destabilization today,
and eventually weaken. But in the short term, small hail remains
possible. Meanwhile, a vigorous shortwave trough over the Upper
Midwest will dig southeastward through the base of a large-scale
mid/upper trough, and yield amplification of this trough southward
across the Great Lakes through Monday morning. Ascent preceding this
shortwave trough will overspread parts of the central/southern
Appalachians into the TN Valley, mainly during the evening and
overnight.

A leading and weaker mid-level perturbation will encourage the
primary surface low to develop eastward across PA this afternoon
through early evening. A surface cold front will extend southwest of
this low into the TN Valley. Convective development along the front
appears likely to be delayed until early evening, as the
strengthening large-scale ascent aids in increasing low-level
convergence along the front amid generally veered flow within the
warm sector. Surface dew points should largely range from the mid
50s in WV to a narrow corridor of low 60s in TN, yielding a plume of
MLCAPE around 500-1500 J/kg amid initially steep mid-level lapse
rates.

Recent guidance still differs regarding storm coverage along/ahead
of the cold front this evening, from almost none to scattered. This
is perhaps in response to the ascent with the shortwave trough
strengthening after peak diurnal heating. The strongest 700 mb
westerlies (around 40-55 kt) should be confined to mainly northeast
of the TN Valley. Forecast hodographs above this level appear small,
owing to weakening winds with height as fast mid/upper flow lags to
the north-northwest. This suggests supercell structures may struggle
to develop/be sustained. But the strong 700 mb flow could support
localized damaging winds in any multicell clusters that can form.
Farther southwest, somewhat greater buoyancy could foster small to
marginally severe hail as well. The overall severe threat appears
likely to remain rather isolated, and no changes have been made to
the Marginal Risk with this update.

..Gleason/Jewell.. 10/13/2024

$$
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ACUS01 KWNS 141233
SWODY1
SPC AC 141232

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0732 AM CDT Mon Oct 14 2024

Valid 141300Z - 151200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today and tonight.

...Synopsis and Discussion...
Isolated thunderstorms will remain possible this morning and
afternoon across parts of New England as an upper trough continues
eastward. Other low-topped convection will be possible today beneath
the upper trough over portions of the Great Lakes, with seasonably
warm lake temperatures and cold mid-level temperatures supporting
modest buoyancy and occasional lightning flashes. Finally, isolated thunderstorms may occur this afternoon and evening across parts of
UT and northern AZ into western CO, as a weak shortwave trough moves
slowly southeastward over the Great Basin and Southwest. Weak
instability across all these regions should greatly limit potential
for severe thunderstorms through the period.

..Gleason/Jewell.. 10/14/2024

$$
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ACUS01 KWNS 111245
SWODY1
SPC AC 111244

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0744 AM CDT Fri Oct 11 2024

Valid 111300Z - 121200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorm potential will remain low today.

...Synopsis and Discussion...
Isolated showers and thunderstorms producing occasional lighting may
persist for a few more hours across eastern/southern OK and vicinity
before diminishing as modest warm advection with a
south-southwesterly low-level jet weakens later this morning.

A cold front will advance southeastward across the Upper Midwest and
Great Lakes through the period. While low-level moisture and related instability are expected to remain quite limited ahead of the front,
cool mid-level temperatures and strong ascent with the upper trough
may support isolated thunderstorms across parts of northern MI this
afternoon and evening. Some of this activity could produce
occasional gusty winds given strengthening low/mid-level flow
through the day, but the overall severe threat still appears low.
The front and upper trough will continue across the Northeast
tonight. But, instability is forecast to remain minimal, which
should hinder thunderstorm potential.

Convection should also develop this afternoon across parts of south
FL and the Keys. Even with poor mid-level lapse rates and warm
temperatures aloft, some of this activity could produce isolated
lightning flashes.

A shortwave trough will move across the northern CA/western OR
vicinity this evening and overnight. Thunderstorms may occur
offshore, but potential for lightning over land appears limited.

..Gleason/Jewell.. 10/11/2024

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ACUS01 KWNS 121236
SWODY1
SPC AC 121234

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Sat Oct 12 2024

Valid 121300Z - 131200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms appear unlikely today and tonight.

...Synopsis and Discussion...
Within broad upper troughing over central/eastern Canada, an
embedded mid-level perturbation will gradually amplify as it moves southeastward over the Upper Midwest and Great Lakes through the
period. At the surface, a weak low will gradually develop eastward
across the Midwest and eventually reach the northwest OH vicinity by
late tonight. An associated cold front will continue moving
southward across the central Plains and upper/mid MS Valley, while a
warm front extending eastward from the surface low remains across
northern IL/IN/OH through this evening.

Limited low-level moisture and weak large-scale forcing across the
warm sector suggest that surface-based thunderstorm potential should
remain low today across the Great Lakes/OH Valley region. However,
most guidance does show some elevated convection developing by late afternoon/early evening across southern Lower MI and vicinity.
00/06Z NAM runs show much more instability present compared to most
other guidance, with a general consensus that around 500 J/kg of
MUCAPE may exist when convection initiates.

Even with strong shear in the cloud-bearing layer, the weak
instability forecast should tend to limit the threat for severe hail
with any thunderstorms that can form over Lower MI and subsequently
spread east-southeastward across northern IN/OH this evening and
overnight. Still, small hail may occur with the more robust cores.
Occasional gusty winds may also be able to reach the surface given
the forecast strength of the low/mid-level flow, presence of a
somewhat dry sub-cloud layer/weak DCAPE, and relatively shallow
near-surface stable layer.

..Gleason/Jewell.. 10/12/2024

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ACUS01 KWNS 101224
SWODY1
SPC AC 101222

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0722 AM CDT Thu Oct 10 2024

Valid 101300Z - 111200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today and tonight.

...Synopsis and Discussion...
With Milton having moved east and off the FL Atlantic Coast,
thunderstorms are not expected over FL through the rest of the
period. Otherwise, isolated convection that may produce occasional
lighting appears possible across parts of the southern Plains and
southeast AZ/southern NM. The activity over the southern Plains will
largely be tied to modest low-level warm advection and weak ascent
associated with a shortwave trough moving southward from NE/KS.
Instability is forecast to remain weak, and severe thunderstorms are
not expected.

..Gleason/Jewell.. 10/10/2024

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ACUS01 KWNS 071236
SWODY1
SPC AC 071234

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Mon Oct 07 2024

Valid 071300Z - 081200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms appear unlikely today and tonight.

...Synopsis and Discussion...
Greatest thunderstorm potential today should exist across south FL
and the Keys, along and south of a ill-defined front draped across
the FL Peninsula. A weak surface low is present over the eastern
Gulf of Mexico this morning, and it is forecast to redevelop off the
southeast FL Coast by this evening. Some modest enhancement to the
low-level flow should occur through the day over south FL and
vicinity, but poor lapse rates should hinder robust updrafts even as
daytime heating occurs. While occasional strong/gusty winds appear
possible with any convection that can develop in this regime, the
overall severe threat appears too limited to include any
probabilities at this time.

Otherwise, thunderstorms will continue moving eastward across parts
of southern New England this morning ahead of a front, with
additional isolated development possible later this afternoon across
parts of the Carolinas. Occasional lightning flashes may also be
noted across parts of the Great Lakes, with low-topped convection
possible beneath cold mid-level temperatures associated with an
upper trough over eastern Canada. Finally, isolated high-based
thunderstorms may develop along parts of the Sierra into NV this
afternoon as a weak shortwave trough moves eastward.

..Gleason/Dean.. 10/07/2024

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ACUS01 KWNS 081232
SWODY1
SPC AC 081230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Tue Oct 08 2024

Valid 081300Z - 091200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL/SOUTH FLORIDA AND THE KEYS...

...SUMMARY...
An isolated tornado threat associated with Hurricane Milton may
develop late tonight into early Wednesday morning across parts of
the central/southern Florida Peninsula and the Keys.

...Florida...
Ongoing thunderstorm activity this morning over south FL and
vicinity along/near a weak baroclinic zone should generally remain
sub-severe through the day, with modest low/mid-level flow limiting
deep-layer shear. The latest NHC forecast shows Hurricane Milton
moving into the southeastern Gulf of Mexico late tonight into early
Wednesday morning. Milton's wind field is also forecast to expand
through the period, with enhanced low-level southerlies expected to
gradually overspread parts of the Keys and south FL late tonight
(mainly after 06Z). A corresponding slow increase in low-level shear
is anticipated in this time frame, which should support some
potential for updraft rotation and isolated tornado/waterspout
threat with any cells in outer rain bands on the eastern periphery
of Milton's center. Still, there is a fair amount of guidance which
shows that any outer rain bands that do manage to form late tonight
into early Wednesday morning may tend to remain offshore from the
Keys and southwest FL Coast. Even with this uncertainty, some threat
for a couple of brief tornadoes may exist across these areas, mainly
in the 06-12Z time frame. The threat for a few tornadoes is expected
to increase into the Day 2/Wednesday time frame (after 12Z/8 AM EDT
Wednesday morning) across a greater portion of central/south FL and
the Keys as Milton approaches the FL Gulf Coast.

..Gleason/Jewell.. 10/08/2024

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ACUS01 KWNS 061246
SWODY1
SPC AC 061245

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 AM CDT Sun Oct 06 2024

Valid 061300Z - 071200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN OHIO...WESTERN NEW YORK/PENNSYLVANIA...AND THE NORTHERN WEST
VIRGINIA PANHANDLE...

...SUMMARY...
Isolated to scattered severe thunderstorms should occur this
afternoon and evening from parts of eastern Ohio into western New York/Pennsylvania, West Virginia, and western Maryland. Damaging
winds and hail should be the main threats.

...Upper Ohio Valley into the Lower Great Lakes and Central
Appalachians...
A vigorous upper trough over Ontario and the Great Lakes will
continue advancing eastward across parts of Quebec and the Northeast
today. A related surface low over northern Ontario this morning will
slowly occlude through the day, while a cold front extending across
the upper Great Lakes and Midwest advances southeastward over the OH
Valley and western Mid-Atlantic by this evening. A narrow corridor
of modest low-level moisture will return northward ahead of this
cold front, with surface dewpoints generally in the 50s to perhaps
low 60s. Modestly steepened mid-level lapse rates overspreading the
warm sector through the day, in tandem with diurnal heating, should
support around 500-1500 J/kg of MLCAPE by mid afternoon. A belt of
enhanced (50-60 kt) mid-level flow attendant to the upper trough
will move over parts of the upper OH Valley, lower Great Lakes, and
western Mid-Atlantic this afternoon and evening. This strong flow
aloft will contribute to substantial deep-layer shear (around 35-50
kt) and organized severe convection.

Current expectations are for robust thunderstorms to develop along
the cold front in eastern OH/western NY and northwest PA around
20-22Z. This initial development may be supercellular given the
strong deep-layer shear, with an associated threat for severe hail
given favorable lapse rates aloft. A brief tornado or two may also
occur. But, a fairly quick transition to a line is anticipated given
the linear forcing of the cold front. As this occurs, the threat for
scattered damaging winds should quickly increase as convection moves east-southeastward from eastern OH across western NY/PA and into
WV/western MD. Given the fairly narrow warm sector, this activity
should weaken by mid evening with the loss of daytime heating, and
as it encounters a much less unstable airmass in the central
Appalachians.

..Gleason/Dean.. 10/06/2024

$$
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ACUS01 KWNS 031238
SWODY1
SPC AC 031236

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 AM CDT Thu Oct 03 2024

Valid 031300Z - 041200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Synopsis/Discussion...
In mid/upper levels, a nearly zonal northern-stream pattern will
prevail either side of the Canadian border, from the Pacific Coast
across the Great Lakes to New England. The main feature perturbing
that belt for this period will be a strongly positively tilted
trough, currently over south-central parts of SK/MB northwestward to north-central AB. This trough will amplify and pivot southeastward/
eastward across northern ON, northern MN and Lake Superior into
tonight. By 12Z, the trailing part of this feature should be moving
across the western U.P of MI, northern WI and central MN. A weak
shortwave trough -- evident in moisture-channel imagery over eastern
OR and southwestern ID -- may reach the Quad Cities area of IA/IL by
12Z tomorrow and phase with the larger trough.

At the surface, 11Z analysis showed a frontal wave low over
northwestern KS, with warm front eastward to west-central/
northwestern MO, and cold front across east-central CO. The low
should migrate eastward through the period, reaching north-central/ northwestern MO by 12Z, with cold front trailing across southern KS,
western OK and the TX South Plains, and warm front extending to
east-central MO and southern IL.

...Mid/upper Mississippi Valley...
Capping and meager boundary-layer moisture will inhibit convective
potential today along/ahead of the front and low. However, an area
of isolated to scattered elevated thunderstorms is possible
overnight northeast of the low, supported by large-scale DCVA/lift
ahead of the ejecting shortwave trough, and warm advection/
isentropic lift to LFC of increasingly moist parcels above the
surface. Activity should be rooted in the 700-800-mb layer, amidst
MUCAPE roughly 500-800 J/kg, and around 35-40 kt effective-shear
magnitudes. This may support small hail, especially early in the
convective cycle when cells are still at least somewhat discrete.
Modes should become messier and precip more expansive fairly
quickly, as inflow-layer moisture and MUCAPE only slowly increase in
the immediate upstream airmass to the southwest. The overall severe
threat appears too limited and conditional for an outlook at this
time.

..Edwards/Dean.. 10/03/2024

$$
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ACUS01 KWNS 041250
SWODY1
SPC AC 041248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Fri Oct 04 2024

Valid 041300Z - 051200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today and tonight.

...Synopsis and Discussion...
Elevated thunderstorms ongoing across west-central IL should
continue for a few more hours this morning, aided by modest warm
advection in the 850-700 mb layer and ascent on the southern
periphery of a shortwave trough over the Upper Midwest. With a
mainly linear mode now dominant, severe hail appears unlikely. This
activity should gradually diminish in coverage and intensity through
the remainder of the morning.

Isolated to scattered thunderstorms will be possible today from
parts of the Mid-Atlantic southwestward to the Gulf Coast/Southeast.
Weak flow and related deep-layer shear will limit the overall severe
threat with any convection that develops across these regions. A
pronounced shortwave trough will move across the Pacific Northwest
and northern Rockies/Plains through tonight. While large-scale
forcing and mid-level flow associated with the upper trough passage
will be strong, thunderstorm coverage is expected to remain sparse
due to a rather dry airmass present across these areas.

..Gleason/Dean.. 10/04/2024

$$
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ACUS01 KWNS 050600
SWODY1
SPC AC 050559

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Sat Oct 05 2024

Valid 051200Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
NORTHERN WISCONSIN AND ADJACENT PORTIONS OF SOUTHERN UPPER MICHIGAN...

...SUMMARY...
Isolated strong to severe thunderstorms may produce hail and gusty
winds across parts of northern Wisconsin into the Upper Peninsula of
Michigan this evening.

...Synopsis...
Flow aloft will remain generally weak over the southern half of the
U.S. today, where upper ridging will prevail. This ridging will --
however -- be interrupted by an elongated/weak trough comprised of
several smaller-scale vorticity maxima, extending from the
southeastern states west-southwestward across the Gulf of Mexico to
northern Mexico.

Farther north, a faster belt of westerly flow will prevail, with an embedded/potent short-wave trough forecast to move across the
northern Plains through the day, and then the Upper Mississippi
Valley/Upper Great Lakes region overnight.

Accompanying the upper trough, a surface low is forecast to advance east-northeastward across the Canadian Prairie, and into
northwestern Ontario through latter stages of the period. A
trailing cold front will shift eastward across the north-central
U.S. and southward across the Plains -- reaching a position from
Lower Michigan southwestward to the Ozarks, and then
west-southwestward across Oklahoma to Far West Texas by Sunday
morning.

...Central and northern Wisconsin north to Lake Michigan...
As a cold front advances across the Upper Midwest area through the
afternoon, a capped boundary layer should hinder convective
development. As the boundary crosses the Upper Mississippi Valley
around sunset, and the upper system advances, the combination of
strong ascent and steepening lapse rates aloft should permit
eventual development of showers and scattered thunderstorms.

With a rather dry -- and nocturnally stabilizing -- boundary layer
expected ahead of the front, convection should evolve within a
slightly elevated but amply unstable layer. Strong southwesterly
flow aloft will provide sufficient shear for organized/rotating
storms -- and thus risk for hail is evident. Additionally, the
strongly dynamic upper system/strong mass response suggests
potential for downward transport of strong flow aloft -- potentially manifesting as severe-caliber wind gusts at the surface. Given the
overall severe risk, will introduce a small SLGT/level 2 risk across
this area, with the primary risk expected to be hail. However,
potential for strong/gusty surface winds may also -- depending upon boundary-layer evolution -- warrant upgrade to 15% probability in
later outlooks.

..Goss/Squitieri.. 10/05/2024

$$
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ACUS01 KWNS 211246
SWODY1
SPC AC 211245

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 AM CDT Sat Sep 21 2024

Valid 211300Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE SOUTHERN HIGH PLAINS...

...SUMMARY...
Scattered severe storms capable of all hazards are possible this
afternoon and evening across portions of the southern High Plains.

...Southern High Plains...
Water-vapor imagery this morning shows a potent mid- to upper-level
low and associated trough moving east across AZ. An associated
70-kt 500-mb speed max will round the base of the trough and move
into central NM by early evening before weakening overnight as it
moves into the TX Panhandle. Southerly low-level flow will maintain
a fetch of seasonably rich moisture across the region today
(reference 12 UTC Del Rio, TX and Midland, TX raobs; 18.3 and 14.9
g/kg lowest 100-mb mean mixing ratios, respectively). Early morning
surface analysis places a cold front pushing southward over the
central High Plains and this boundary will reach northeast NM and
parts of the Panhandles late this afternoon/early evening.

Some continuation of ongoing shower/thunderstorm activity may
continue through the morning across eastern NM into the TX
Panhandle, lending some uncertainty in airmass
destabilization/recovery in wake of this convection. 06z model
guidance (particularly the NAM) seemed to reasonably depict the
low-level moisture plume emanating from the Rio Grande
Valley/Edwards Plateau northwestward into the southern High Plains.
Steep 700-500 mb lapse rates (7.5 to 8.0 deg C/km) sampled this
morning from Albuquerque and Midland will combine with daytime
heating to yield a moderately unstable airmass by afternoon across
eastern NM into west TX. Increasing large-scale deep-layer ascent
approaching from the west and frontal/orographic lift will likely
contribute to scattered thunderstorms developing relatively early
this afternoon. Forecast hodographs indicate supercells will evolve
within this environment. The risk for large hail/severe gusts will
likely accompany the stronger storms, and a threat for a few
tornadoes may be realized later this afternoon/early evening from
eastern NM into parts of adjacent west TX.

...Upper Midwest to Mid MO Valley...
A northern-stream short-wave trough will continue to move eastward
from southern MB/Dakotas into MN/northwest ON during the period.
A surface cold front will advance into MN-western IA-southern NE by
midday, before accelerating east into the Upper Great Lakes, while
the trailing portion of the boundary pushes south-southeast into
central KS by early to mid afternoon. This boundary will serve as
the focus for potential convective development during the late
afternoon, though surface heating is not expected to be particularly
strong ahead of the wind shift. With the strongest forcing expected
to spread across northwest ON, convection may be more isolated along
the front trailing across the Upper Midwest. Even so, some hail/wind
threat will exist with this activity which should peak in intensity
during the early evening.

...Western PA into western VA...
Weak short-wave trough will dig southeast across the upper OH Valley
later this afternoon with modest mid-level northwesterly flow
expected to extend across western PA/VA. This feature will encourage
scattered convection later this afternoon along a frontal zone that
will be draped across the Delmarva-western PA into western NY.
Models suggest scattered storm coverage and forecast soundings would
imply some of the stronger storms being capable of an isolated risk
for wind damage (50-60 mph) and perhaps some hail. This activity
will likely diminish by early evening coincident with nocturnal
cooling.

..Smith/Broyles.. 09/21/2024

$$
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ACUS01 KWNS 221240
SWODY1
SPC AC 221238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Sun Sep 22 2024

Valid 221300Z - 231200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
WEST TEXAS THROUGH THE OZARKS AND INTO THE LOWER OHIO VALLEY...

...SUMMARY...
Isolated severe thunderstorms are possible from west Texas to
western Kentucky.

...West Texas into the Ozarks and lower OH Valley...
An upper low over CO will continue to slowly weaken as it migrates
eastward into the central Great Plains through early Monday morning.
A belt of moderate southwesterly mid-level flow will reside in
between the closed circulation and a flattening anticyclone centered
over the northwest Gulf of Mexico. In the low levels, a south and southeastward movement of a surface front is forecast through today
as it moves through the Corn Belt and areas farther southwest in the
southern Great Plains.

Showers and isolated thunderstorm activity this morning extends
along and behind the front from OK northeastward into the lower MO
Valley and western Great Lakes. Considerable cloud cover will
contribute to limited diurnal heating, especially from near the Red
River northeastward into the Ozark Plateau. Morning surface
analysis shows a reservoir of lower 70s deg F dewpoints over the
Edwards Plateau (reference the 12 UTC Del Rio, TX raob showing a
capped but deep moist layer) with 65-70 F farther northeast from OK
through the Ozarks. Forecast soundings later this afternoon
indicate 500-2000 J/kg MLCAPE---supporting a risk for a few stronger thunderstorms near/behind the boundary/wind shift. Strong to
locally damaging gusts (50-60 mph) and perhaps hail up to around 1
inch in diameter are possible mainly this afternoon into the early
evening.

..Smith/Broyles.. 09/22/2024

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ACUS01 KWNS 231236
SWODY1
SPC AC 231235

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0735 AM CDT Mon Sep 23 2024

Valid 231300Z - 241200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE OZARKS
TO THE OHIO/TENNESSEE VALLEYS REGION...

...SUMMARY...
Isolated strong to severe thunderstorms are possible mainly this
afternoon into the early evening from the Ozarks into parts of the
Tennessee and lower Ohio Valleys.

...Ozarks into TN/OH Valleys and southern Appalachians...
Water-vapor imagery this morning shows a digging trough over eastern
MT with it forecast to move into the Dakotas this afternoon. A
positive-tilt mid-level trough over the central Plains will move
east and deamplify over the MS Valley overnight. This evolution is
expected to aid weak surface wave/low development along the synoptic
front over the Ozarks before moving to the IL/IN border by early
Tuesday morning. Ongoing showers/thunderstorms over southeast MO
will continue east into the lower OH Valley this morning and temper destabilization through at least midday. In its wake, models
indicate MLCAPE in excess of 1000 J/kg developing from AR into
western KY/TN, coincident with modest 0-6km bulk shear. The surface
boundary will serve as the focus for scattered convection later
today with some of the stronger storms potentially capable of a
localized severe threat. This activity is expected to diminish
during the evening.

Farther east, isolated to scattered thunderstorms will probably
develop near the ridge tops of the southern Appalachians and
adjacent parts of the Carolinas Piedmont this afternoon. Moist low
levels coupled with heating will result in around 1000 J/kg MLCAPE.
Some modest multicell organization may occur due to adequately
strong upper-level westerly flow. However, weak flow in the lowest
5 km and modest lapse rates will probably temper the overall
potential for localized strong gusts (40-55 mph).

..Smith/Broyles.. 09/23/2024

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ACUS01 KWNS 241243
SWODY1
SPC AC 241242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Tue Sep 24 2024

Valid 241300Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
KENTUCKY INTO SOUTHERN OHIO AND WEST VIRGINIA...

...SUMMARY...
Isolated to scattered severe thunderstorms are possible mainly this
afternoon across portions of the Ohio and Tennessee Valleys into the central/southern Appalachians. A few strong/severe storms are also
possible across portions of the southern Plains.

...Ohio and Tennessee Valleys to southern Appalachians...
Water-vapor imagery this morning shows a mid-level vorticity maximum
moving across the middle MS Valley and into the OH Valley. A belt
of moderate to strong southwesterly 500-mb flow (25-50 kt) will
overspread KY and the surrounding states, with the strongest flow
generally within the Slight Risk bounds. Bands of showers/weak
thunderstorms are ongoing this morning from middle TN into OH, and
in a separate area over eastern IL immediately ahead of the surface
low. This low will migrate east-northeast into southern Lower MI by
early evening with a frontal zone extending south-southwest into the
Mid South. In wake of the early morning convection, some cloud breaks/destabilization is forecast with upwards of 750-2000 J/kg
MLCAPE from the southern Great Lakes into the southern Appalachian
states. Ample deep-layer speed shear (via mostly southwesterly flow
through the troposphere) will aid in storm organization into
organized multicells and probably several supercells. Only notable
change this outlook update was to include portions of the southern
Great Lakes in low-severe probabilities for potential activity
near/ahead of the surface low. The primary concern across the
general region will likely be damaging winds with the stronger
storms.

...OK vicinity...
An amplifying large-scale trough over the MS Valley will feature a
60-kt 500mb speed max moving southward into the central Great Plains
by early evening on the backside of the upper trough. Left exit
region of this feature will encourage large-scale ascent, and a weak
surface wave/low should evolve over southwest KS/northwest OK by
early afternoon. Strong heating will contribute to 750-1250 J/kg
MLCAPE by mid afternoon across OK with flow veering and
strengthening with height. Elongated hodographs will support the
potential for hail growth with a few of the stronger/sustained
updrafts that evolve. An isolated threat for large hail (1 to 1.75
inches in diameter) and/or severe gusts (60-70 mph) will probably
peak during the 23z-03z period before storms weaken during the late
evening.

..Smith/Broyles.. 09/24/2024

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ACUS01 KWNS 241647
SWODY1
SPC AC 241645

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1145 AM CDT Tue Sep 24 2024

Valid 241630Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF TN/KY/OH/WV AND CENTRAL OK...

...SUMMARY...
Isolated to scattered severe thunderstorms are possible mainly this
afternoon across portions of the Ohio and Tennessee Valleys into the central/southern Appalachians. Severe storms will also be possible
across portions of Oklahoma.

...Ohio and Tennessee Valleys to southern Appalachians...
Have spatially adjusted/expanded the Slight Risk based on
observational trends and somewhat stronger destabilization across
areas such as northern/middle Tennessee. Water-vapor imagery shows a
mid-level vorticity maximum moving across the middle Mississippi
Valley and into the Ohio Valley. A belt of moderate to strong
southwesterly 500-mb flow (25-50 kt) will overspread Kentucky and
the surrounding states. A surface low will migrate east-northeast
into southern Lower Michigan by early evening, where isolated severe
storms are possible, with a frontal zone extending south-southwest
from this low into the Mid South.

In the wake of early morning convection, modest cloud
breaks/destabilization is forecast with upwards of 750-2000 J/kg
MLCAPE from the southern Great Lakes into the southern Appalachians,
with the strongest destabilization expected across Tennessee into
southern Kentucky and possibly the western Carolinas pending the timing/abatement of lingering cloud cover. Regionally, ample
deep-layer speed shear will aid in storm organization into organized
multicells and probably several supercells. Damaging winds will be
the most common hazard, but isolated large hail will be possible,
and some tornado risk may exist as well.

...Oklahoma/North Texas...
Have upgraded portions of central Oklahoma for what is expected to
be a semi-focused regional corridor of large hail potential late
this afternoon and early evening. The region will be influenced by
the immediate backside of a southeastward-moving upper-level trough
centered over the Lower Missouri Valley. A considerably
strengthening cyclonically curved belt of westerlies aloft will
influence Oklahoma, overspreading a relatively moist air mass, with
lower to some middle 60s F surface dewpoints likely to persist
through the diurnal heating/mixing cycle.

Near a deepening surface low and nearby triple point/warm front, at
least isolated storms are expected to develop as early as
mid-afternoon (3-4pm), becoming more probable with a greater
coverage through sunset. Overall buoyancy will not be robust, with
MLCAPE generally not expected to exceed 1000 J/kg later this
afternoon. However, this buoyancy, along with steep lapse rates and
robustly vertically veering wind profiles, accentuated by 35-45 kt northwesterly mid/upper-level flow, should support initial
supercells capable of large hail (potentially golfball size), along
with some potential for damaging wind gusts.

These storms will persist generally southeastward through the
evening into southern/southeast Oklahoma, and probably north Texas
overnight. Overall intensity will tend to wane nocturnally after
sunset, but some severe hail/wind potential will probably linger,
particularly on the west/southwest flank of any evolving clusters of
storms, which will be increasingly elevated to the east of the warm
front.

..Guyer/Lyons.. 09/24/2024

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ACUS01 KWNS 251323
SWODY1
SPC AC 251323

Day 1 Convective Outlook RESENT 2
NWS Storm Prediction Center Norman OK
0823 AM CDT Wed Sep 25 2024

Valid 251300Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
GULF COAST INTO THE SOUTHERN/CENTRAL APPALACHIANS AND FLORIDA PENINSULA...

...SUMMARY...
Isolated severe storms are possible this afternoon from parts of the
Southeast and central/southern Appalachians to the Texas/Louisiana
Gulf Coast. Some tornado threat may develop across the Florida
Peninsula by this evening, in association with Tropical Cyclone
Helene.

...Southeast and southern Appalachians...
Widespread precipitation is expected from parts of the Southeast
into the southern Appalachians, due to the combined influence of the mid/upper-level flow to the west and moisture streaming north from
the Gulf of Mexico and Helene. While this will tend to limit
available buoyancy in some areas, strong to locally severe storms
will be possible with initial development, with preconvective MLCAPE
of around 1000 J/kg possible. This will generally be coincident with
favorable deep-layer shear, especially across the southern
Appalachians vicinity where a few supercells could occur pending
sufficient destabilization. Locally damaging wind gusts and perhaps
a tornado could accompany the strongest storms, before low/mid-level
lapse rates and buoyancy become increasingly weak with time, and an outflow-reinforced front sags southward across the region.

...Texas Gulf Coast/Middle Gulf Coast...
Somewhat stronger diurnal destabilization will be possible from
parts of central/east Texas into Louisiana, and perhaps into
Mississippi, with MLCAPE potentially increasing above 1500 J/kg.
Isolated to widely scattered thunderstorm development will be
possible near a southward-moving cold front. Effective shear will
generally range from 25-35 kt, and a few modestly organized storms
are possible. Isolated damaging gusts could accompany the strongest
storms within this regime.

...Florida Peninsula and Keys...
Helene's wind field is forecast to be rather large, especially on
the east side of the circulation, associated with what is expected
to be a strengthening Helene through the afternoon and night.
Reference the National Hurricane Center for the latest Helene
details. This scenario will result in modestly strengthening
low-level shear/SRH across the Florida Peninsula during the day, but
more so into the evening and overnight after the peak diurnal
instability cycle. Instability will likely remain rather weak
overall, and details regarding the intensity of any outer rain bands
remain uncertain. However, some tropical-cyclone tornado threat
could evolve across parts of the Florida Peninsula and Keys, mainly
into tonight.

...Eastern Washington/northern Idaho/northwest Montana...
While buoyancy is expected to remain quite weak, relatively steep
mid-level lapse rates will support thunderstorm potential late this
afternoon through early evening from eastern Washington into
northern Idaho and northwest Montana, in advance of the approaching
shortwave trough. Most guidance suggests that instability will
remain too weak for an organized severe threat, although rather
strong deep-layer flow/shear could support a strong storm or two
with locally gusty winds and small hail. Subsequent outlooks will
reevaluate the possibility of introducing low severe probabilities.

...Upper Ohio Valley to the Lower Great Lakes...
Weak to locally moderate buoyancy may develop later today from parts
of the upper Ohio Valley into the lower Great Lakes region, between
a weakening cold front approaching from the west, and a slow-moving
warm front draped from central Pennsylvania into western New York.
Moderate southwesterly midlevel flow will support effective shear of
35-45 kt, sufficient for storm organization. However, with
persistent cloud cover and mid-level lapse rates expected to remain
rather weak, storm intensity and any attendant severe threat could
be relatively limited. Confidence in sufficient destabilization
remains too low to add severe probabilities.

..Guyer/Broyles.. 09/25/2024
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ACUS01 KWNS 260101
SWODY1
SPC AC 260059

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Wed Sep 25 2024

Valid 260100Z - 261200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
SOUTHERN APPALACHIANS INTO PARTS OF THE SOUTHEAST AND FLORIDA...

...SUMMARY...
Isolated strong to severe storms are possible this evening from the
southern Appalachians into parts of the Southeast. Some tornado
threat may develop later tonight over Florida, in association with
Hurricane Helene.

...Florida...
Hurricane Helene is forecast to intensify and move north to
north-northeastward across the southeast Gulf of Mexico tonight; see
NHC forecasts/advisories for more information. Helene's large wind
field will continue to overspread the Florida Peninsula and Keys
tonight, with low-level shear/SRH becoming increasingly favorable
for low-topped supercells with a potential tornado threat.
Low-topped supercell potential prior to 12Z Thursday morning remains
uncertain, with inland instability expected to remain relatively
limited. Outer rain bands could begin to affect the western
Peninsula later tonight, while convection may persist near a
convergence zone near the east coast.

...Southern Appalachians vicinity into parts of the Southeast...
Widespread precipitation is ongoing this evening within a corridor
from the FL Panhandle into western NC/VA, but weak to locally
moderate buoyancy persists east of this band, with regional VWPs and
the 00Z RNK sounding depicting vertically veering wind profiles
favorable for organized convection. Generally weak low/midlevel
lapse rates will tend to limit storm intensity, but marginal
supercell potential may persist through the evening, with a threat
of isolated damaging gusts and possibly a tornado.

...Northern ID/northeast WA/northwest MT...
While low-level moisture is limited, steep lapse rates and ascent
attendant to an approaching mid/upper-level shortwave trough are
supporting a high-based storm cluster currently moving across the ID
Panhandle. This cluster has a history of 60-65 mph gusts, and will
move across northwest MT early this evening, with a continued threat
of strong to locally severe gusts.

..Dean.. 09/26/2024

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ACUS01 KWNS 281240
SWODY1
SPC AC 281238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Sat Sep 28 2024

Valid 281300Z - 291200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Synopsis/Discussion...
The mid/upper-level pattern features mean ridging over the West and
troughing in the East. The pattern is anchored by a large, nearly
stacked cyclone -- resulting from the combination of an antecedent
midlatitude low with the post-tropical remnants of Helene. The
cyclone should remain centered over the lower Ohio Valley region, drifting/wobbling erratically eastward over northern KY through the
period, while continuing to fill. The strongest associated mid/
upper-level winds should remain mostly behind a low-level frontal
zone extending from the northern Gulf across northern FL to the
coastal Carolinas. South of the boundary across parts of peninsular
FL, sufficient low-level moisture remains -- amid weak to negligible
MLCINH and a deep troposphere with modest but sufficient lapse rates
for convection. This will support scattered thunderstorms today
over FL, with isolated thunderstorm potential over coastal areas of GA/Carolinas near the boundary. Dry midlevel air and lack of
greater flow/shear should keep severe potential too isolated and
disorganized for an outlook.

Elsewhere, just east of the mean ridge and amid northerly flow very
peripheral to the cyclone, a patch of marginally favorable low/
middle-level moisture should combine with diurnal heating of higher
terrain over parts of northern NM and southern CO. Scattered
showers are expected this afternoon, with isolated to widely
scattered convection extending above a mid/upper-level stable layer
and into icing regions suitable for lightning generation. Isolated thunderstorms also are possible amid weak but sufficient low-level
moisture and instability around parts of the eastern Great Lakes.

..Edwards/Broyles.. 09/28/2024

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ACUS01 KWNS 291230
SWODY1
SPC AC 291228

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0728 AM CDT Sun Sep 29 2024

Valid 291300Z - 301200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast for today.

...Synopsis/Discussion...
A highly amplified, slow-moving, mid/upper-level pattern will
persist over much of the CONUS, south of a progressive northern
stream near and north of the Canadian border. A norther-stream
trough, nearly synoptic in scale, is apparent in moisture-channel
imagery from central/southwestern BC to near-coastal WA/OR. This
feature should amplify and move eastward across southwestern Canada
and the interior Northwest through the period, reaching east- central/south-central SK, central MT and western WY by 12Z tomorrow.
Weak, basal height falls and modest midlevel moisture will
contribute to the potential for isolated, high-based convection over
portions of UT, some of which may extend deep enough to generate
lighting and strong gusts, into a deeply mixed boundary layer. Weak moisture/buoyancy (MLCAPE generally less than 100 J/kg) precludes an unconditional severe area.

As the northern-stream trough moves away from CA, a formerly cut-off
low now moving ashore into south-central CA will become cut off
again, and drift southward/southwestward back toward the Pacific by
the end of the period. Ridging will weaken greatly over the
northern Plains and Upper Midwest ahead of the northern-stream
trough, but will persist at its root over the Four Corners region.
To its east, a longstanding, stacked, gradually filling cyclone will
drift erratically eastward over the TN/KY border area, possibly
devolving into an open-wave trough by the end of the period.
Associated convection to its east will encounter a relatively warm/
stable layer in mid/upper levels, limiting but not entirely
suppressing potential for convection to reach into icing layers
suitable for lightning. As such, isolated thunder will be possible
from the central Appalachians to the Tidewater. Although warm
midlevels will extend southward to most of FL, rich boundary-layer moisture/theta-e south of a quasistationary frontal zone over
northern FL will support sporadic thunderstorm potential, mainly
from midday through early evening.

..Edwards/Broyles.. 09/29/2024

$$
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ACUS01 KWNS 301239
SWODY1
SPC AC 301237

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0737 AM CDT Mon Sep 30 2024

Valid 301300Z - 011200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today, though a few strong
storms may affect central/eastern North Carolina.

...Synopsis/Discussion...
The main belt of mid/upper-level, midlatitude westerlies will
continue to traverse the northwestern/north-central CONUS and central/southwestern Canada, buckled cyclonically around a prominent
synoptic trough now located from eastern SK to central MT and
western WY. This trough should phase with another now over central
mainland Arctic Canada by the end of the period, resulting in a
500-mb low over southeastern Nunavut, with trough trailing over
western Hudson Bay, northwesternmost ON, MN, and IA.

Strongly difluent flow aloft will take shape southeast of the
trough, across the Mississippi Valley, the Great Lakes from
Michigan/Huron on down, the Ohio Valley, and much of the
Appalachians. As that occurs, a longstanding, filling, weakening
low now over southwestern WV will devolve today to an open-wave
trough, losing amplitude rapidly and drifting eastward over the
central Appalachians through the period. Part of a basal shortwave trough/vorticity lobe -- now apparent in moisture-channel imagery
over eastern TN -- will eject eastward across northern NC and
southern VA from this afternoon through tonight.

At the surface, 11Z analysis showed a quasistationary front across
northern SC to just south of the southern Outer Banks, extending
from a triple-point low near CAE. This boundary should shift
northward over central/eastern NC through the day. Meanwhile, a
cold front -- related to the strong northern-stream trough -- was
drawn from central/southern MB across southern ND, central SD,
northwestern NE, and southern WY. This front should sweep across
most of the Great Plains and upper Mississippi Valley through the
period, reaching northern Lower MI, IL, southwestern MO, southern
OK, and the TX South Plains by 12Z.

...Central/eastern NC...
Widely scattered showers and thunderstorms are expected to develop
this afternoon over the Piedmont and coastal plain, in an
environment characterized by rich boundary-layer moisture (surface
dewpoints commonly in upper 60 to mid 70s F) very weak ambient
MLCINH easily removed by diurnal heating, but weak mid/upper-level
lapse rates. This will result in 500-1200 J/kg MLCAPE over most of
the area from he Piedmont to the Sounds, beneath a belt of
sufficiently strong mid/upper flow to yield around 35-45-kt
effective-shear magnitudes.

Low-level hodographs over central/eastern NC this afternoon, from
model forecast soundings, reasonably show curvature near the frontal
zone, but with weak speeds in the lowest couple km that
substantially limit SRH and vector shear. However, above 1 km,
hodographs are somewhat long and straight, suggesting the potential
for low-end supercells amidst the mode common multicellular modes.
At this time, forecast shear appears too weak to support an
unconditional tornado-threat area, but the scenario will be
monitored for any mesoscale enhancement to shear (especially along
boundaries) that may introduce such a risk. The gust threat appears
subsevere at this time, though localized gusts approaching severe
limits cannot be ruled out.

..Edwards/Broyles.. 09/30/2024

$$
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ACUS01 KWNS 011227
SWODY1
SPC AC 011225

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0725 AM CDT Tue Oct 01 2024

Valid 011300Z - 021200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Synopsis...
In mid/upper levels, the main belt of westerlies is expected to
remain near the Canadian border through the period, extending across
more of the Great Lakes with time. That will occur as a synoptic-
scale trough -- evident in moisture-channel imagery from a low over
westernmost parts of Hudson Bay across northwestern ON to the upper
Mississippi Valley -- ejects northeastward over northern ON, and
James and Hudson Bays, through the period. This stronger flow will
remain well poleward of thunder potential today near a weakening/
ejecting trough over the Tidewater region, south of a weak front
over FL, and under or south of a weakening synoptic ridge over parts
of CO/NM/AZ. Vertical shear and lapse rates aloft will be too weak
in any of those areas to support organized severe potential.
Locally strong gusts may accompany the high-based convection in AZ,
with a deep/well-mixed subcloud layer, but only modest (5-15 kt)
midlevel easterlies. A cold front sweeping across the Great Lakes,
Ohio Valley, lower Mississippi Valley, and southern Plains, should
encounter a marginally moist/unstable airmass for isolated thunder,
within a band of convection over parts of the eastern Great Lakes.

..Edwards/Dean.. 10/01/2024

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ACUS01 KWNS 021235
SWODY1
SPC AC 021233

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0733 AM CDT Wed Oct 02 2024

Valid 021300Z - 031200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Synopsis/Discussion...
The mid/upper-level pattern will be characterized by a belt of
gently difluent, west-northwesterly northern-stream flow from the
Pacific Northwest to the Great Lakes. This flow will weaken
considerably and become much more difluent over the Ohio Valley, mid Mississippi Valley and Appalachians. The strongest flow aloft will
be well-displaced from any substantial low-level moisture/theta-e,
which is expected to remain along and south of a quasistationary
front draped across north-central FL.

Scattered daytime thunderstorms are expected to form along FL East
and West Coast sea breezes, shifting inland as the boundaries
(including outflows from the first generation of convection nearer
the coasts) merge. Weak deep-layer flow and lack of shear will
preclude organized severe potential. Localized strong gusts are
possible in wet downbursts with enhanced lift along colliding
boundaries, 1500-2000 J/kg preconvective MLCAPE, and rich inflow-
layer moisture (surface dewpoints 70s F and PW commonly over 2
inches). Elsewhere, very isolated/brief lightning may occur near
the AZ/NM border and Mogollon Rim, but with barely enough moisture
for convection, coverage is expected to be too small for a 10% area.

..Edwards/Dean.. 10/02/2024

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ACUS01 KWNS 161629
SWODY1
SPC AC 161628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1028 AM CST Sat Nov 16 2024

Valid 161630Z - 171200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Synopsis/Discussion...
Morning water-vapor imagery depicts a midlevel shortwave trough
tracking eastward from eastern MT into the Dakotas. This feature
will continue eastward across the northern Plains/Canadian Prairies
into the overnight/early morning hours. In the 04-12Z time frame,
associated cooling aloft atop a cool/stable boundary layer will
contribute to weak elevated instability across the Upper Midwest.
Given strong low-level warm advection and midlevel ascent preceding
the trough, isolated thunderstorms are possible.

Farther south, a separate low-level jet will promote a band of
showers over the Upper TX Coast during the overnight hours. Related
low-level warming/moistening will contribute to weak instability,
though dry air aloft should generally limit lightning potential.

..Weinman.. 11/16/2024

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ACUS01 KWNS 171632
SWODY1
SPC AC 171630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1030 AM CST Sun Nov 17 2024

Valid 171630Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...

...SUMMARY...
Scattered severe thunderstorms are expected to develop across parts
of west/northwest Texas into southwest Oklahoma this evening and
continuing through daybreak on Monday, posing a risk for severe wind
gusts and a few tornadoes.

...Synopsis...
Water-vapor imagery this morning shows a potent mid-level low/trough
over northwest Mexico with a downstream ridge centered over the
eastern Gulf of Mexico. A mid-level vorticity maximum near the
middle part of the Gulf of California will pivot east into Chihuahua
by mid evening while the larger-scale trough becomes negatively
tilted and moves northeastward into the southern High Plains. In
the low levels, cyclogenesis over northern Mexico will gradually
evolve today before the surface low deepens tonight reaching the
northwest TX/western OK vicinity at the end of the period.
Seasonably moist air via southeasterly flow from the western Gulf
will advect into west TX before a Pacific front sweeps eastward
across the Chihuahuan Desert and portions of the southern High
Plains tonight. An attendant warm frontal zone will advance
northward from north TX into OK late.

...Southern Great Plains...
The 12 UTC Fort Worth, TX observed sounding showed an adequately
moist/deep moist layer featuring a mean mixing ratio of 12.6 g/kg.
The richer low-level moisture, featuring dewpoints in the mid-upper
60s as of late morning, is currently near the I-35 corridor from the
Metroplex and areas south/southeast. Moisture advection will
contribute to gradual destabilization through this evening across
parts of west TX northeastward into southwest OK despite
considerable cloud cover through the day. As an intense 100-kt
500-mb speed max moves from Chihuahua into west TX overnight,
large-scale ascent will favor the development of scattered
thunderstorms initially developing near the Permian Basin vicinity
and becoming more widespread as very strong low-level warm advection
attendant to an intensifying LLJ develops tonight. Model guidance
indicates 250-1000 J/kg MLCAPE across the destabilizing warm sector.
A forced band of storms will likely evolve tonight across west TX
and rapidly move northeast in the area southeast of the surface low
track. As the squall line matures, the propensity for severe gusts
will probably increase despite relatively poor lapse given the
intense flow expected to develop. It remains uncertain if cellular
development will occur either ahead of the line or be loosely
maintained in parts of the larger band of storms. Nonetheless,
elongated and enlarged hodographs will favor a risk for scattered
severe gusts and possibly a tornado risk, especially as the squall
line encounters greater moisture from west-central TX northeastward
into southwest OK late.

..Smith/Weinman.. 11/17/2024

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ACUS01 KWNS 181301
SWODY1
SPC AC 181259

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0659 AM CST Mon Nov 18 2024

Valid 181300Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...AND FROM PORTIONS OF EAST TEXAS INTO LOUISIANA
AND FAR SOUTHERN ARKANSAS...

...SUMMARY...
Thunderstorms may continue to produce occasional strong to severe
gusts and perhaps a couple brief tornadoes across parts of north
Texas into central Oklahoma this morning. A threat for a few
tornadoes and damaging winds will also exist this afternoon and
evening from parts of east Texas into Louisiana and vicinity.

...Synopsis...
A negatively tilted shortwave trough over the southern High Plains
this morning will eject northeastward across the central Plains and
mid MO Valley through this evening. Attendant 80-100 kt mid-level
jet will likewise overspread OK/KS into western MO by late
afternoon, while a strong (50-60+ kt) southerly low-level jet aids
in northward moisture transport across parts of the southern/central
Plains and lower/mid MS Valley. At the surface, a deep low over
western OK will develop northeastward through the day in tandem with
the ejecting shortwave trough, eventually reaching the Upper Midwest
late tonight. A related cold front will sweep quickly eastward
across the southern/central Plains and into the mid MS Valley
through the period, before decelerating over the lower MS Valley
late tonight into early Tuesday morning.

...Southern Plains...
With low-level winds remaining very strong per area VWPs (up to
50-60 kt at 1 km AGL), an ongoing QLCS across central/southern OK
into north-central TX may continue to pose a risk for occasional
strong to severe winds in the short term this morning as it moves east-northeastward. Ample low-level shear will also support a
continued threat for embedded circulations and a couple brief QLCS
tornadoes this morning. This line is expected to outpace better
low-level moisture return and already weak instability in the next
couple of hours (see very weak surface-based instability in 12Z
soundings from OUN/FWD). Accordingly, nearly all guidance shows
gradual weakening of the line over the next several hours as it
moves into eastern OK and northeast TX. Still, at least an isolated
threat for strong to damaging winds and perhaps a tornado could
persist, even as the thermodynamic environment becomes increasingly
marginal with eastward extent.

...East Texas into the Lower Mississippi Valley...
The southern portion of the squall line along/ahead of the cold
front should tend to remain weak through early afternoon, before
potentially restrengthening by mid/late afternoon into the early
evening. This should occur as the line/cold front encounters a more
buoyant airmass across parts of east TX into LA and southern AR,
where MLCAPE may reach up to 500-1000 J/kg with daytime heating,
even though mid-level lapse rates will remain poor. This region will
remain displaced well south of better forcing associated with the
ejecting shortwave trough. Even so, strengthening mid-level
southwesterly flow through the day will support 40-50 kt of
deep-layer shear and some threat for supercells ahead of the front.
Sufficient southerly low-level winds will also support adequate 0-1
km shear and a threat for a few tornadoes. Most high-resolution
guidance shows either the line restrengthening and/or supercells
developing ahead of it by late afternoon. Have therefore included a
Slight Risk from parts of east TX into LA and vicinity to account
for this potential.

...Central Plains/Ozarks into the Mid Missouri Valley...
Later today, a secondary area of thunderstorms may form closer to
the surface low and behind the initial QLCS from north-central OK
into central/eastern KS and eventually the mid MO Valley. This
convection may develop in a modestly steep mid-level lapse rate
environment amid more unidirectional southwesterly deep-layer flow
near the exit region of the mid-level jet. Even though instability
will remain weak, a couple of strong to severe thunderstorms may
pose an isolated risk for gusty winds, a tornado, and perhaps
marginally severe hail. Based on latest guidance trends, have
expanded the Marginal Risk northward some to include parts of the
mid MO Valley.

..Gleason/Kerr.. 11/18/2024

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ACUS01 KWNS 191254
SWODY1
SPC AC 191252

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0652 AM CST Tue Nov 19 2024

Valid 191300Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL GULF COAST...

...SUMMARY...
Thunderstorms producing isolated strong wind gusts and perhaps a
tornado are possible across the central Gulf Coast vicinity today.

...Central Gulf Coast...
The primary upper cyclone, with multiple embedded shortwave troughs,
will evolve into a closed mid/upper-level low over the northern
Plains and Upper Midwest today. A deep surface low over MN this
morning should continue to slowly occlude as it moves northward into
Canada by this evening. A cold front extends southward from this low
to the lower MS Valley/central Gulf Coast states. Showers and
thunderstorms are ongoing this morning across southern LA/MS/AL
along and ahead of the front. Poor lapse rates noted on the observed
12Z sounding from LIX, along with cloudiness and widespread
pre-frontal precipitation will generally hinder any more than weak destabilization from occurring over land through this afternoon.
Even so, the southern extent of a 30-40 kt south-southwesterly
low-level jet is forecast to migrate slowly eastward today across
the central Gulf Coast vicinity. A brief waterspout and/or tornado
appears possible with low-topped rotating cells along or very near
the coast given adequate 0-1 km SRH and greater low-level moisture
present (generally 70s surface dewpoints). Otherwise, isolated
damaging wind gusts may occur with convection moving eastward along
or just ahead of the front. Meager instability should keep the
overall severe threat isolated.

..Gleason/Kerr.. 11/19/2024

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ACUS01 KWNS 221243
SWODY1
SPC AC 221242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0642 AM CST Fri Nov 22 2024

Valid 221300Z - 231200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are unlikely through tonight.

...Synopsis/Discussion...
A well-amplified mid/upper-level pattern features synoptic-scale
cyclones on either side of the CONUS:

1. In the East, the cyclone core is elongated west-southwest/east-
northeast from WV to southern New England, occasionally exhibiting
two centers at 500 mb. This cyclone should pivot offshore
gradually, with a more consolidated center south of RI and east of
NJ by 12Z tomorrow. Associated thunder tonight should remain
offshore.

2. For the Pacific cyclone, a double center was evident as well,
with the strongest, closest, and most important one being near
45N131W. This is becoming the primary low as the other one well to
the west devolves into an open shortwave trough. The eastern low
should pivot northward, offshore from the Northwest Coast, toward
Vancouver Island. Meanwhile, a series of small shortwaves and
vorticity lobes will move ashore in the preceding southwest flow,
predominantly this afternoon through tonight -- each contributing
shots of cooling/destabilization aloft, and atop the weakly unstable
marine air mass. Forecast soundings accordingly suggest that the
midlevel inversion should rise/cool such that modest buoyancy
(overland MUCAPE generally under 250 J/kg) extends upward into icing
layers suitable for at least isolated/brief lightning, especially
from around 00Z onward. A few thunderstorms are possible near the
coast, as well as embedded in the deep low/middle-level moisture
fetch impinging on higher terrain in northern CA.

..Edwards.. 11/22/2024

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ACUS01 KWNS 231243
SWODY1
SPC AC 231241

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0641 AM CST Sat Nov 23 2024

Valid 231300Z - 241200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are unlikely through tonight.

...Synopsis/Discussion...
In mid/upper levels, the presence of a cyclone near the coastal
Northeast, and progressive synoptic ridging moving eastward over the
central CONUS, should contribute to keeping most of the lower 48
states too dry and/or stable in low/middle levels for thunderstorms.
A substantial synoptic-scale trough is apparent in moisture-channel
imagery from north-central BC south-southwestward, offshore from the
Pacific Northwest and CA. Shortwave troughs and vorticity lobes
will continue to eject inland within southwest flow, across the
Pacific Northwest and northern Rockies, as a cutoff cyclone forms
offshore from Vancouver Island and retrogrades southwestward.

One of those shortwave perturbations is evident from central OR to
northern CA, and will destabilize a marginally moist low/middle-
level profile enough to support isolated thunderstorms as far inland
today as portions of MT. This feature should develop a small,
closed cyclone overnight near the southern part of the AB/SK border,
while a trailing perturbation crosses northern CA and the northern
Great Basin. Ahead of that feature, and beneath cold midlevel
temperatures closer to the cyclone core, isolated thunderstorms will
be possible near the Pacific Coast, from northwestern CA to the
Olympic Peninsula. The greatest buoyancy and deepest convective
towers accessing the marine layer should remain offshore, though
strong gusts or small hail may accompany the strongest near-shore
cells inland a short distance. Severe potential appears too
isolated and conditional to warrant an outlook area.

..Edwards/Leitman.. 11/23/2024

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ACUS01 KWNS 241232
SWODY1
SPC AC 241231

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0631 AM CST Sun Nov 24 2024

Valid 241300Z - 251200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are unlikely through tonight.

...Synopsis/Discussion...
In mid/upper levels, a belt of relatively strong flow will bend
cyclonically from CA to the central Great Plains, changing curvature
through a low-amplitude, eastward moving synoptic ridge over the
Upper Great Lakes and Ohio Valley, then cyclonically again across
the Mid-Atlantic and New England. A long-lasting, deeply occluded
cyclone will move eastward from the Canadian Maritime Provinces
through the period. Upstream, a smaller cyclone -- initially
located over southern SK -- will move slowly eastward to southern MB
by 12Z tomorrow, with trough southward over the Dakotas. However,
too little moisture will be available for a general thunderstorm
outlook. Farther west, a synoptic-scale cyclone offshore from the
Olympic Peninsula and Vancouver Island will pivot slowly southward
then eastward through tonight, but will remain over Pacific waters.
Intervening ridging should remain over the northern Rockies and
vicinity. However, cold air aloft and steep low/middle-level lapse
rates will overlie a moist marine layer, supporting isolated to
widely scattered, episodic thunder mainly offshore. Some of this
activity may move inland before dissipating in more-stable low-level conditions.

A shortwave trough -- evident in moisture-channel imagery south and
east of the ridge from the Yellowstone region across the northern
Great Basin to central CA -- is forecast to move quickly eastward
across the central Rockies and central Plains through the period,
phasing with the SK/MB low by 12Z tomorrow. The associated cold
front was drawn at 11Z today across an area of low pressure
extending from northeastern NE to southwestern KS, then arching over southeastern CO. A warm front was drawn over southeastern KS and
southwestern MO, with a secondary warm front over southern IA and
northern IL. The low should consolidate today across northeastern
KS into northern MO, and move to near the southwestern shore of Lake
Michigan by the end of the period, when the cold front reaches to
near a line from BMI-STL-FSM-SPS-HOB. Scattered elevated showers
are possible late tonight near and north of the warm front, across
parts of northeastern IL, WI, Lower MI, IN, and OH. However, the
warm conveyor will lack rich moisture, and forecast soundings
reasonably suggest buoyancy will be too shallow and strongly capped
for an areal thunderstorm threat.

..Edwards/Leitman.. 11/24/2024

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ACUS01 KWNS 251228
SWODY1
SPC AC 251226

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0626 AM CST Mon Nov 25 2024

Valid 251300Z - 261200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
No severe-thunderstorm areas are forecast through tonight.

...Synopsis/Discussion...
A progressive, lower-amplitude pattern will prevail across the CONUS
this period, compared to the preceding week. A small cyclone now
centered over the southern SK/MB border area is forecast to
accelerate slightly and elongate southeastward, reaching that part
of ON just north of the MN border by 12Z tomorrow. As this occurs,
a basal shortwave trough -- apparent in moisture-channel imagery
from eastern SD to western CO -- should move eastward. This trough
will cross the mid/upper Mississippi Valley in the 21-03Z time
frame, then become negatively tilted, reaching Georgian Bay,
southern ON, and Lake Erie by 12Z.

The associated surface frontal-wave low was analyzed at 11Z from a
low over northern IL, southwestward near STL, FYV and ADM, to a weak
low near HOB. By 00Z, the main/northern low should reach eastern
Lower MI, with cold front across western parts of OH/KY/TN, northern
parts of LA/MS, and the TX Gulf Coastal Plain. By 12Z, the cold
front should extend from eastern PA across western parts of VA/NC,
northern GA/AL, southern MS/LA, and across the northwestern Gulf
shelf waters to near BRO.

Farther west, another mid/upper-level cyclone was centered over
Pacific waters west of OR, near 44N130W. This feature is expected
to devolve to an open-wave, positively tilted trough as it
approaches the coast today. The trough should cross the coast
between the Olympic Peninsula and northwestern CA obliquely, from
north-south, from 00Z to 12Z. Preceding the trough, DCVA/cooling in
midlevels will steepen lapse rates and support potential for
isolated thunderstorms, particularly over the relatively moist
Pacific boundary layer near the coast.

...Lower Mississippi to Tennessee Valleys...
Stronger deep-layer/large-scale lift will occur near the front in
the Ohio Valley to north-central Appalachians, but with poor
moisture return greatly limiting overall buoyancy. Somewhat greater
moisture -- but still in quite incompletely modified return-flow
trajectories with dewpoints generally low/mid 60s F in a shallow
layer -- is forecast in a narrow prefrontal corridor over the lower
Mississippi to Tennessee Valleys from late afternoon through this
evening. However, weak low/middle-level lapse rates (only barely
above moist adiabatic) will limit buoyancy there, with MLCAPE mostly
remaining under 500 J/kg. Briefly enlarged low-level hodographs
appear in some forecast soundings along or just east of the
prefrontal moist axis, especially from northern/eastern LA to
northern MS, suggesting non-zero storm-scale rotation potential for
any cell(s) that can mature fast enough before moving out of
surface-based inflow. At this time, severe risk appears too minimal
and conditional for an outlook. However, the scenario will be
revisited for evidence of greater unconditional potential, in
succeeding outlook cycles.

..Edwards/Leitman.. 11/25/2024

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ACUS01 KWNS 301241
SWODY1
SPC AC 301240

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0640 AM CST Sat Nov 30 2024

Valid 301300Z - 011200Z

...NO THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected today.

...Discussion...
Longwave troughing will persist east of the Rockies, with prevalent
surface high pressure and cool/stable conditions. This will
contribute to a virtually nil thunderstorm potential across the
CONUS. An exception may the possibility of a few lightning flashes
in the immediate lee of Lakes Erie and Ontario, although this
potential should remain limited/sporadic overall.

..Guyer/Broyles.. 11/30/2024

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ACUS01 KWNS 011300
SWODY1
SPC AC 011258

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0658 AM CST Sun Dec 01 2024

Valid 011300Z - 021200Z

...NO THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms are not expected through tonight.

...Discussion...
Longwave troughing and prevalent cyclonic flow aloft will continue
to prevail east of the Rockies while an upper ridge builds over the
West. A cool/stable pattern via the influence of high pressure and
continental trajectories will considerably limit convective
potential today and tonight. Shallow convection will persist in lake
effect bands off Lakes Erie and Ontario, but the potential for
lightning flashes should remain limited. Across far south Texas,
warm advection along a coastal front near the lower Texas coast
could lead to an increase in convection, although the potential for thunderstorms inland is expected to remain low.

..Guyer/Broyles.. 12/01/2024

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ACUS01 KWNS 021252
SWODY1
SPC AC 021250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0650 AM CST Mon Dec 02 2024

Valid 021300Z - 031200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Discussion...
Longwave troughing will remain prevalent over the East with
continued surface high pressure and mostly dry/stable conditions
east of the Rockies. This scenario will considerably limit deep
convective potential. A couple of lightning flashes could occur
across parts of Deep South Texas, in conjunction with relatively
rich low-level moisture and weak but persistent forcing for ascent.
Low-topped convective snow bands, potentially including a couple of
lightning flashes, are also expected over portions of the Great Lakes today.

..Guyer/Broyles.. 12/02/2024

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ACUS01 KWNS 031301
SWODY1
SPC AC 031259

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0659 AM CST Tue Dec 03 2024

Valid 031300Z - 041200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms are possible along the south Texas Coast, but
severe thunderstorms are not expected.

...Discussion including South Texas...
A persistent longwave trough over the eastern CONUS will be
reinforced by an amplifying and southeastward-digging upper trough
over the Canadian Prairies toward the Upper Midwest and Great Lakes
through tonight. A continued prevalence of surface high pressure and cool/stable continental trajectories will considerably limit and
spatially confine thunderstorm potential. Across Deep South Texas,
weak mid-level height rises are expected, with persistent weak
low-level ascent and moistening near a coastal boundary, further
influenced by strengthening southeasterly low-level flow/warm
advection late today and tonight. Elevated convection over inland
areas on the cool side of the boundary may produce occasional
lightning, potentially in a northward-expanding fashion tonight.
Modest surface-based destabilization may develop inland along the
immediate coast late this afternoon into tonight, but low-level SRH
and lapse rates/parcel accelerations are expected to remain weak,
and thus severe thunderstorms are unlikely.

..Guyer/Broyles.. 12/03/2024

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ACUS01 KWNS 041259
SWODY1
SPC AC 041258

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0658 AM CST Wed Dec 04 2024

Valid 041300Z - 051200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Scattered thunderstorms are expected from North/East Texas to the
ArkLaMiss today and tonight. Severe thunderstorms are not currently
expected.

...East/Southeast Texas to southwest Louisiana...
Widely scattered elevated thunderstorms have developed through the
early morning hours across east-central/parts of North Texas, with
persistent convection also off the coast of South Texas near a weak
surface wave, and into the maritime warm sector where a narrow zone
of near 70F/lower 70s F dewpoints reside. Some northward inland
advancement of the Texas coastal front is expected today with a
related increase in low-level moisture. However, low-level lapse
rates are expected to remain weak due to semi-persistent multi-layer
cloud cover and muted heating.

While low-level SRH is currently weak per 12z observed soundings and
regional WSR-88D VWP data, it is expected to increase within the
zone of warm advection, particularly near the inland-advancing
frontal boundary, coincident with modest surface-based
destabilization this afternoon along the middle/upper Texas coast,
and eventually southwest Louisiana this evening. While a few weakly
rotating storms could occur offshore, current thinking is that the
supercell and related tornado/wind potential will remain limited
inland, largely due to the poor low-level lapse rates and weak
parcel accelerations.

..Guyer/Broyles.. 12/04/2024

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ACUS01 KWNS 051256
SWODY1
SPC AC 051255

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0655 AM CST Thu Dec 05 2024

Valid 051300Z - 061200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Discussion...
An upper trough will continue to shift quickly east-northeastward
today over the Lower Great Lakes and Northeast, with a secondary
speed max/clipper-type wave spreading southeastward over
Manitoba/northern Ontario toward the Upper Great Lakes tonight. Over
the Southwest, an upper low will remain quasi-stationary over the
southern Arizona and northwest Mexico vicinity.

Along the middle Gulf Coast, a few isolated elevated thunderstorms
may still occur early today, but the overall convective potential is
expected to dwindle as a cold front continues south-southeastward
into the northern Gulf of Mexico. Elsewhere, isolated lightning
flashes could occur tonight with a potential increase in elevated
convection across far West Texas/far southern New Mexico in advance
of an upper low over northwest Mexico, and possibly near the Deep
South Texas coast. Severe storms are unlikely in each of these
scenarios as overall buoyancy will be limited.

..Guyer/Broyles.. 12/05/2024

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ACUS01 KWNS 061255
SWODY1
SPC AC 061254

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0654 AM CST Fri Dec 06 2024

Valid 061300Z - 071200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected. Isolated weak thunderstorms
are possible today from southeast Arizona and southern New Mexico to
East Texas.

...Discussion...
Rising heights are expected today over much of the northern tier and
eastern seaboard in the wake of an exiting prominent upper-level
trough, while a slow-moving upper low persists over southern
portions of Arizona/New Mexico and northwest Mexico. A few
thunderstorms will be possible near/east of this upper low,
potentially including parts of southeast Arizona, southern New
Mexico, and far west Texas within a marginally unstable environment.
Modestly increasing warm advection/elevated moisture transport into
tonight should lead to an increase in elevated convection across
Texas, some of which will be capable of lightning, particularly
across central/north-central Texas tonight.

..Guyer/Broyles.. 12/06/2024

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ACUS01 KWNS 071257
SWODY1
SPC AC 071255

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0655 AM CST Sat Dec 07 2024

Valid 071300Z - 081200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Discussion...
Within a split flow regime, the southern-stream upper low over the
Southwest Deserts/northern Mexico will become more
east-northeastward progressive today, while a low-amplitude belt of
progressive westerlies evolves across the northern tier and Canada.

Semi-persistent and east/northeastward-expanding thunderstorm
potential today will be focused across much of central/east/north
Texas and possibly nearby parts of the ArkLaTex and/or far southeast
Oklahoma. These will be elevated thunderstorms aided by DPVA and semi-persistent warm advection and elevated moisture transport.
Severe thunderstorms are unlikely given the limited buoyancy.
Elsewhere, a few lightning flashes could occur late tonight near
coastal Washington as lapse rates steepen in the wake of an
inland-advancing front.

..Guyer/Broyles.. 12/07/2024

$$
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ACUS01 KWNS 081243
SWODY1
SPC AC 081242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0642 AM CST Sun Dec 08 2024

Valid 081300Z - 091200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Discussion...
Split upper-level flow will initially prevail over the CONUS, with
an east/northeastward-accelerating southern-stream shortwave trough
advancing from the southern Plains to the Tennessee Valley and Lower
Ohio Valley, while an additional upper trough amplifies over the
Northwest. A broad area of warm advection will support scattered
elevated convection today near the upper Texas coast and southern
Louisiana, northward into North Texas/southeast Oklahoma and the
ArkLaTex region. The potential for lightning-producing convection is
expected to expand east-northeastward toward the ArkLaMiss and
Mid-South into tonight. Due to the elevated nature of the convection
and weak instability, severe weather is not expected.

..Guyer/Broyles.. 12/08/2024

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ACUS01 KWNS 091259
SWODY1
SPC AC 091257

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0657 AM CST Mon Dec 09 2024

Valid 091300Z - 101200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms are possible from the Lower Mississippi Valley into
much of the Southeast States today and tonight. The potential for
severe thunderstorms currently appears low.

...Southeast States...
Neutral height tendencies will tend to prevail over the region as a low-amplitude shortwave trough over the Lower Ohio Valley and
Tennessee Valley races east-northward toward the Mid-Atlantic
seaboard. Convergence will tend to remain weak diurnally near a northward-shifting warm front across the Tennessee Valley, until
modest surface cyclogenesis occurs tonight across the ArkLaMiss and
Mid-South, coincident with a stronger secondary cold front
accelerating southeastward across the ArkLaMiss/East Texas.
Semi-steady warm/moist advection will persist in/near the warm
sector spanning parts of Louisiana/Mississippi/Alabama into
eventually nearby portions of Georgia and Tennessee.

The persistent warm advection regime over the middle Gulf Coast will
maintain isolated thunderstorm chances through the day. Despite
40-50 knot mid-level flow, weak low to mid-level lapse rates will
modulate updraft intensities and tend to limit the likelihood of
overly organized convection for much of the day.

The potential for thunderstorms should regionally increase tonight
as the aforementioned upstream cold front/modestly deepening surface
low interact with higher theta-e air. Even with favorable low-level moistening/destabilization trends, the scenario may not provide
sufficient destabilization for robust deep convection tonight. As
mentioned in the prior outlook discussion, most convection-allowing
guidance remains rather subdued as far as severe attributes, with
the typically aggressive FV3 being a modest exception.

Subsequent outlooks will closely reevaluate this scenario and the
potential need for low wind/tornado probabilities, as more favorable destabilization trends could prompt more of a severe risk given the severe-conducive deep-layer/low-level shear.

..Guyer/Broyles.. 12/09/2024

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ACUS01 KWNS 101240
SWODY1
SPC AC 101239

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0639 AM CST Tue Dec 10 2024

Valid 101300Z - 111200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
THE CENTRAL GULF COAST REGION INTO CENTRAL/SOUTHERN GEORGIA AND THE
FLORIDA PANHANDLE...

...SUMMARY...
A few strong to severe thunderstorms are possible across portions of
the central Gulf Coast region into central/southern Georgia and the
Florida Panhandle through tonight.

...Synopsis...
In mid/upper levels, mean troughing over the central CONUS will
evolve from positively to near neutrally tilted through the period,
in conjunction with two predominant subsynoptic-scale processes:
1. South-southeastward digging of a cyclone now over extreme
northern MB, reaching the MB/ON border east of Lake Winnipeg by 12Z
tomorrow;
2. Eastward shift of a strong, basal shortwave trough -- now
evident in moisture-channel imagery over northern NM into
south-central AZ -- absorbing a weaker/trailing perturbation and
reaching from middle TN to central LA by the end of the period.

As this occurs, a surface cold front -- analyzed at 11Z from a low
near BNA southwestward across northwestern MS, central LA, middle TX
Coast, and deep south TX -- should extend from western PA across the
southern Appalachians and southwestern AL, to southeastern LA, by
00Z. A low-level, prefrontal confluence/convergence zone may
intensify this evening and tonight over portions of the FL
Panhandle, southeastern AL and southwestern GA. The cold front
should approach and perhaps overtake the confluence zone by 12Z, as
it reaches a position from central PA across the western Carolinas,
to near a MCN-AAF line, then over the northeastern/central Gulf.

...Southeast...
Widely scattered, ongoing thunderstorms clusters are apparent across
portions of southern MS into southeastern LA, with a marginal
potential for a brief tornado or strong-severe gust. See SPC
mesoscale discussion 2255 for near-term coverage of this scenario.
Similarly sporadic, isolated and marginal tornado and severe-gust
potential will exist throughout today and tonight with convection
along and just ahead of the cold front, as well as slowly increasing
convective coverage from late afternoon through overnight in the
prefrontal convergence zone. The warm-sector environment will
remain characterized by a nearly saturated boundary layer with
surface dewpoints commonly in the upper 60s to near 70 F along the
coast, to mid 60s well inland, amidst nearly moist-adiabatic
low-level lapse rates. Somewhat greater boundary-layer instability
is possible this afternoon in the inflow to the near-frontal
convection, as modest heating occurs through cloud breaks. That my
offset weak midlevel lapse rates enough to support peak MLCAPE
around 1000 J/kg from southeastern LA to south-central AL,
decreasing northeastward as well as eastward. An axis of lesser
buoyancy -- with MLCAPE remaining in the 500-800 J/kg range, should
shift eastward tonight near the confluence line, in support of
convection there.

Deep shear should increase from late this afternoon through tonight
with the more neutral tilt of the larger-scale trough aloft, and
related tightening of the mid/upper height gradient over the warm
sector. While strongest flow aloft will remain behind the front, effective-shear magnitudes of 45-55 kt and elongated low-level
hodographs are forecast from the northeastern Gulf Coast to the
Carolinas. As the basal shortwave trough approaches (but remains
behind the cold front), the LLJ should strengthen to 45-55 kt
tonight over southern GA, reaching 55-65 kt over eastern NC, with
lengthening but only somewhat curved low-level hodographs. The
northeastward extent of the conditional severe potential may extend
into near-coastal SC/NC; however, poor low- and middle-level lapse
rates (with stable layers apparent in forecast soundings) are
precluding any expansion of unconditional probabilities
northeastward for this outlook cycle. The main (yet marginal)
severe threat for the Carolinas still appears to hold off until
early day 2.

..Edwards/Jewell.. 12/10/2024

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ACUS01 KWNS 111241
SWODY1
SPC AC 111239

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0639 AM CST Wed Dec 11 2024

Valid 111300Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE EASTERN
CAROLINAS TO SOUTHERN NEW ENGLAND...

...SUMMARY...
Severe thunderstorm winds and a few tornadoes are possible from the
eastern Carolinas to southern New England. Isolated severe
thunderstorms may occur southward into portions of Florida.

...Synopsis...
Moisture-channel imagery showed a substantial mid/upper trough
extending from a cyclone over the MB/ON border southward over the
Mississippi Valley to a strong, basal shortwave trough over portions
of MS/LA. The latter feature is forecast to pivot eastward to the
TN Valley and FL Panhandle through 18Z, then turn northeastward
across WV, western VA and the west-central Carolinas by 00Z. As
that occurs, the entire synoptic trough will become more negatively
tilted, with preceding speed maxima of 160-180-kt at 250 mb, 110-125
kt at 500 mb, and 70-85 kt at 700 mb over parts of the Atlantic
Coast States.

A cold front precedes the main mid/upper trough, and was analyzed at
11Z from east-central PA over western VA to a weak low near AVL,
then across central/southwestern GA and the west-central FL
Panhandle, to the central Gulf. The front should sweep eastward
across VA, the Carolinas, GA and most of FL today, with a 00Z
position progged from VT across western Long Island, over Atlantic
waters to near or just offshore HSE, then southwestward over more of
the Atlantic to southeastern FL. The front should proceed offshore
from the remaining Atlantic Coast by around 12Z tomorrow.

...East Coast States...
An ongoing, prefrontal band of convection, with scattered to widely
scattered embedded thunderstorms, was apparent in radar, satellite
and lightning data from the northeastern Gulf northeastward across
the FL Big Bend region and southern/eastern GA. This activity
should proceed eastward across much of FL and offshore from GA
today, with isolated potential for damaging to severe gusts and/or a
tornado, as it encounters foregoing diabatic surface destabilization
and boundary-layer theta-e advection. The main changes this cycle
are to the associated "marginal area, to:
1. Trim on the southwest edge in deference to ongoing convective
trends (faster than earlier guidance), and
2. Add somewhat more of central/southwestern FL to the
5%-wind/Marginal area to give the trailing part of the main squall
line more room to weaken, as diurnal heating of a moist airmass
somewhat offsets weakening trends in both large-scale and frontal
forcings.

Meanwhile, the most dense potential for damaging to severe gusts is
expected to develop farther north today across central/eastern parts
of the Carolinas, northeastward along the coast into southern New
England. As the shortwave and synoptic troughs assume negative
tilt, synoptic to frontal-scale lift will increase and overlap,
resulting in a narrow band of convection (some with lightning, but
potentially a majority without) firming up into the Mid-Atlantic and
perhaps southern New England. The aforementioned deep-layer wind
maxima will contribute to fast embedded cell motions and downward
momentum transfer within this band. Intense associated gusts
sporadically should penetrate a deeply near-neutral to slightly
above moist-adiabatic layer of lapse rates -- with a shallow
near-surface absolutely stable layer possible -- from around the
Delmarva region northeastward, beneath MUCAPE of around 300-800
J/kg. Buoyancy will become more surface-based with southern extent
from southeastern VA southward, with the greatest values of
low-level shear/SRH and largest hodographs expected over eastern NC
in and near the area of relatively peaked tornado probabilities.
Line-embedded supercells and/or QLCS mesovortices will be the main
tornado concern, with the wind threat more generalized to any
sustained, bow/LEWP segments within the line.

..Edwards/Jewell.. 12/11/2024

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ACUS01 KWNS 121218
SWODY1
SPC AC 121217

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0617 AM CST Thu Dec 12 2024

Valid 121300Z - 131200Z

...NO THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Thunderstorms appear unlikely through tonight.

...Synopsis/Discussion...
A mid/upper-level cyclone -- initially over northern ON -- will
break down as another develops across central QC today, within the
same larger-scale troughing regime. As the resulting low ejects
northeastward over northern QC, and synoptic ridging moves from the
Rockies to the Plains States, heights will rise over most of the central/eastern CONUS. The air mass east of the Rockies mostly will
remain too dry and/or stable for thunderstorms, behind the cold
frontal passage related to the departing eastern trough. One
exception may be in the lake-effect regimes east of the lower Great
Lakes, where steep low/middle-level lapse rates will support plumes
of heavy convective snow. However, shallowness of buoyancy/ELs
precludes more than very brief/isolated lightning potential at most,
and the threat appears too conditional and limited for outlook areas.

A cyclone now located off the coast of OR and northwestern CA will
move inland and devolve slightly to a strong shortwave trough,
reaching northern CA and western/southern NV by 00Z. By 12Z, the
trough will reach southern ID, UT and AZ. Strong DCVA/cooling aloft
is expected immediately to its east today and tonight, from the
Great Basin to the Colorado Plateau and UT/southwestern WY.
However, with dry air in low levels over most of the region,
midlevel moisture/buoyancy should remain too weak and isolated for
enough lightning to justify an outlook area.

..Edwards/Jewell.. 12/12/2024

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ACUS01 KWNS 131244
SWODY1
SPC AC 131243

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0643 AM CST Fri Dec 13 2024

Valid 131300Z - 141200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Synopsis/Discussion...
As heights rise in the East following the departure of a substantial synoptic-scale trough, two strong shortwave troughs will progress
through the midlatitude westerlies upstream, and influence thunder
potential across the western/central CONUS:

1. A leading perturbation -- now apparent over the eastern Great
Basin and southern ID -- should extend from southeastern WY across
east-central CO to eastern NM by 00Z. By the end of the period, the
trough should reach central portions of SD/NE/KS and northwestern
OK, while deepening. A closed 500-mb low may develop on the trough,
either then or within a few hours into day 2, over south-central/
southeastern NE. Strong, foregoing low-level warm advection and
moisture transport will persist through the period, atop a
relatively stable near-surface layer. Increasing thunderstorm
coverage is expected after about 06Z from the middle/upper TX Coast
to the lower Missouri Valley, as increasingly moist parcels above
that stable layer reach LFC. This will occur in concordance with
steepening low/middle-level lapse rates and decreasing MUCINH,
mainly related to the warm advection (but also late DCVA over
northwestern parts of the outlook area). Small hail may fall from
the strongest cells; however, forecast soundings indicate effective
shear, buoyancy and inflow-layer moisture content should be too
small for a severe threat.

2. The trailing shortwave trough -- initially evident in moisture-
channel imagery over the North Pacific around 40N150W -- will move
rapidly eastward and amplify, with preceding large-scale ascent
reaching the CA/OR coastline after 06Z on either side of a low-level
cold front. While lapse rates in the frontal band should be modest,
and buoyancy meager, areas of MUCAPE around 50-200 J/kg, rooted near
700 mb -- may extend deeply enough into suitable icing layers to
support isolated lightning.

..Edwards/Goss.. 12/13/2024

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ACUS01 KWNS 141253
SWODY1
SPC AC 141251

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0651 AM CST Sat Dec 14 2024

Valid 141300Z - 151200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE BAY
AREA AND NEARBY COASTAL CALIFORNIA...

...SUMMARY...
Isolated strong to marginally severe, low-topped thunderstorms are
possible for a few more hours across the Bay Area and nearby coastal California.

...Synopsis...
A progressive mid/upper-level pattern over the CONUS features two
primary troughs promoting convective potential this period, from
east to west:
1. A strong shortwave trough was apparent in moisture-channel
imagery over the central Plains from west-central NE to western OK,
with a 500-mb low apparent near HYS. The low is expected to move
eastward along I-70 into near COU by 00Z, with trough northward to
southern IA and southward to southern AR. By the end of the period,
the low should reach northeastern IL around IKK, along a trough
aligned roughly from MKE-BNA.
2. A synoptic-scale trough from the Gulf of Alaska to offshore from
the CA Coast, including a small cyclone off western WA and a basal
shortwave now approaching coastal central/northern CA.

At the surface, 11Z analysis showed a low over KS between ICT-FRI,
with cold front southwestward across southwestern OK and portions of west-central/southwest TX. By 00Z, the low should become nearly
stacked under the 500-mb low over north-central MO, with cold front
extending over northwestern AR, and northeast TX, to near AUS and
between DRT-LRD. Substantial weakening of the front should be
underway by then, especially south of the Ozarks, with surface winds
less than 10 kt on both sides of the front over east and south TX.
The TX portion of the front should nearly dissipate overnight.

...Bay Area and vicinity...
Isolated strong-severe gusts and hail near severe limits are
possible this morning near the coast, in about a 150-nm-long
corridor centered just south of SFO.

A low-level frontal band precedes the basal shortwave trough over
CA, with associated precip forecast to continue spreading obliquely eastward/southeastward down the Sierra and -- to a lesser extent --
over central/southern CA. Behind that, strong cooling aloft --
related to DCVA immediately preceding the mid/upper trough -- is
supporting favorable instability through a deep-enough layer for
thunderstorms, with areas of 200-500 J/kg MLCAPE apparent over the
Pacific marine layer between SFO and the OR border. That plume of
buoyancy will expand southeastward past the MRY area over the next
few hours, combining with favorable deep shear (40-50 kt
effective-shear magnitudes) to support slight onshore penetration of strong/isolated severe thunderstorms, before activity weakens in
lower inland theta-e. Convection should move over the outlook area
through midmorning local time, before the trough passes.

...East to southeast TX...
Large-scale ascent preceding the eastern mid/upper trough -- in the
form of DCVA over northern parts of the thunder outlook area and a
broad plume of low-level WAA/moisture transport -- will continue to
support scattered, predominantly elevated thunderstorm potential
from the Arklatex to the lower Missouri and mid Mississippi Valleys.
Farther south across east TX to near the upper TX Coast, isolated to
widely scattered thunderstorms are possible through this afternoon.
This activity also will be tied mainly to the WAA plume, and related
isentropic ascent to LFC. Forecast soundings show potential for
inflow-layer parcels to become surface-based amid continuing warming
from both advective and diabatic processes. Wind profiles will veer
with height, though lower midlevel (roughly 600-700 mb) weaknesses
and lack of greater winds even higher in altitude will limit bulk
shear, with effective-shear magnitudes generally remaining below 40
kt. Counterbalancing effects precluding unconditional severe threat
include rising heights throughout the day, stable layers and other
areas of weak lapse rates in midlevels that will keep MLCAPE from
getting much greater than 1000 J/kg, and weakening of both frontal
and large-scale lift with time.

..Edwards/Goss.. 12/14/2024

$$
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ACUS01 KWNS 151225
SWODY1
SPC AC 151224

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0624 AM CST Sun Dec 15 2024

Valid 151300Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
NORTH TEXAS TO THE OZARKS...

...SUMMARY...
Isolated hail near severe limits is possible tonight from portions
of north Texas to the Ozarks.

...Synopsis...
In mid/upper levels, a low-amplitude longwave pattern will remain in
place over the CONUS, with progressive shortwave to synoptic troughs
traversing the prevailing westerlies. The leading trough --
currently anchored by a closed low near the northern IL/IN border --
should devolve to an open wave and move to the northern Mid-Atlantic
region by 12Z tomorrow. Meanwhile, a series of shortwaves and
vorticity lobes -- occupying broadly cyclonic flow over much of the
western CONUS -- will consolidate/phase somewhat through the period
while shifting eastward. By 00Z, a loosely organized synoptic
trough will extend from the Dakotas across the central High Plains
to AZ. Overnight, a closed 500-mb low should develop over southern
MB, with the trough extending across central NE/KS to southern NM
and northwestern MX by 12Z.

At the surface, 11Z analysis showed a decaying cold to stationary
front from eastern IL across southern AR, north-central and west-
central TX. This boundary will move slowly northward through the
day and continue to weaken. Meanwhile, cold frontogenesis is
forecast today ahead of the mid/upper trough, and over parts of the central/northern Plains. This Plains front should reach western
parts of MN/IA, northeastern to south-central KS, and the TX
Panhandle by 00Z. By 12Z, the cold front should reach central/
southern IL, the Ozarks, eastern/southern OK, and the TX South
Plains region.

...North TX to the Lower OH Valley...
Episodic, isolated to scattered thunderstorms are expected
throughout the period, embedded in a plume of low-level warm/moist
advection and moisture transport extending from central/east TX to
the lower Ohio Valley. Through the day, this activity will occur in
weak midlevel lapse rates and modest deep shear, with most or all of
it elevated over a relatively stable, near-surface layer, and
accordingly minimal severe potential. Meanwhile, surface dewpoints
in the 60s F will spread northward into and across much of the
outlook area, as the older boundary becomes diffuse ahead of the
Plains cold front.

Concurrent with height falls aloft and increasing deep shear, the
warm conveyor and accompanying isentropic ascent to LFC should
intensify this evening amid mass response to the consolidation/
approach of the mid/upper trough, and related 45-55-kt LLJ.
Greatest thunderstorm coverage in the plume is expected after about
03Z from near the Red River Valley to the Ozarks, spreading into the
lower Ohio Valley from around 09Z onward. During phases when
convection is still relatively discrete, and around the southern
part of denser/later convective coverage, the most vigorous cells
may produce severe hail. Forecast soundings show a nearly
saturated, near-neutral stability profile in the boundary layer over
north TX to eastern OK, and perhaps into some of northwestern AR,
depending on outflow timing/intensity. This renders profiles that
may be effectively surface-based, with MLCAPE in the 1000-1500 J/kg
rage and slightly greater MUCAPE, but still often containing weak,
near-surface static stability. At this time, severe-gust/tornado
potential appears too conditional and low to draw even marginal
categorical probabilities for those hazards, and the previous
outlook area still appears to capture the consensus of most
probable, favorably positioned convection in the plume as well.

..Edwards/Goss.. 12/15/2024

$$
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ACUS01 KWNS 161226
SWODY1
SPC AC 161224

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0624 AM CST Mon Dec 16 2024

Valid 161300Z - 171200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected through tonight.

...Synopsis/Discussion...
A progressive mid/upper-level pattern will persist, with the most
important feature being a trough now apparent in moisture-channel
imagery from a low over southeastern MB, across western MN, eastern
NE, central KS, and the TX Panhandle. The main/northern part of
this trough is forecast to weaken and move across the Upper Great
Lakes today. A weaker, positively tilted, basal vorticity banner
will move eastward from the TX Panhandle across much of OK today,
and more slowly moving eastward over northwest TX. By 00Z, this
lobe should weaken and extend from the Ozarks to southern OK and the
Permian Basin, then become diffuse and perhaps dissipate overnight.

As that occurs, a surface cold front -- analyzed at 11Z from eastern
IA across southwestern MO, central/southwestern OK and northwest TX
-- should move eastward/southeastward by 00Z to near a TOL-EVV-DYR-
LIT-DAL-6R6 line. Overnight, the southern part of the front will
move slowly southeastward then become quasistationary, reaching a
position across northern parts of AL/MS/LA, northeast/north-central
TX and the Hill Country. Episodic, widely scattered thunderstorms
in bands and clusters are possible near the front, becoming isolated
to widely scattered in the warm sector.

A few strong thunderstorms may develop this afternoon from the
Arklatex into the Mid-South, near time of peak diurnally driven
buoyancy. This activity will be within the warm-advection/moisture-
transport conveyor, and along/ahead of the surface cold front. A
narrow corridor of prefrontal MLCAPE should range from about 2000
J/kg in northeast TX, where heating and moisture will be greatest,
to around 1000 J/kg in eastern AR. However, during the surface warming/destabilization peak window, surface flow will be veering
and remaining weak, due to the shift of the mid/upper trough and
related large-scale lift and mass response away from the area. This
will act both to shrink hodographs and weaken frontal convergence
with time. Given these offsetting factors, and the increasing
dominance of the unfavorable ones with time during the afternoon,
severe probabilities appear too low and conditional for an outlook
area at this time.

..Edwards/Goss.. 12/16/2024

$$
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ACUS01 KWNS 171256
SWODY1
SPC AC 171255

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0655 AM CST Tue Dec 17 2024

Valid 171300Z - 181200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE RED RIVER REGION INTO WESTERN TENNESSEE...

...SUMMARY...
Isolated severe thunderstorms are possible tonight through early
morning Wednesday across parts of the Red River region into western Tennessee.

...Synopsis...
In mid/upper levels, nearly zonal flow was evident over the CONUS
from coast to coast, perturbed by several minor shortwaves. One of
these, however, will amplify through the period and influence
convective potential: a trough now apparent in moisture-channel
imagery over the interior Pacific Northwest. This feature will dig southeastward today and begin to phase with a lesser trough now over southeastern MT and eastern WY. The combined trough should reach
western MN, eastern SD, central NE, and central/western CO by 00Z.
By 12Z, the trough should strengthen further, and extend near a line
from DBQ-IRK-TUL-CDS.

At 11Z, an outflow boundary was drawn from northwestern GA across
central parts of AL/MS to northeastern LA and near TXK, where it
intersected a slow-moving, weakening, cold to quasistationary front
drawn near a CRW-CSV-HSV-ELD-CRS line. Farther north, frontogenesis
and cyclogenesis will occur today over the central Plains, as the
amplifying mid/upper trough approaches. By 00Z, a frontal-wave low
should be located near TOP, with cold front southwestward across
south-central KS, northwestern OK, the TX Panhandle, and
northeastern NM. The low should move past PAH into western KY by
12Z, with cold front over eastern to southwestern AR, central to
southwest TX, and the TX Big Bend region. The outflow boundary and
residual front are expected to move slowly northward over the
Arklatex and Mid-South regions through late evening, before being
overtaken by the cold front.

...Red River region to Mid-South...
Isolated to widely scattered thunderstorms may develop on either
side of the northward-moving, slowly modifying outflow boundary from
this afternoon into this evening. As the cold front intercepts that
boundary, scattered thunderstorms should form tonight along the cold
front. A marginal threat for all severe hazards exists, mainly
overnight.

As the pre-cold-frontal boundaries shift northward, a relatively
undisturbed warm-sector airmass will spread over most of the outlook
area before the cold front arrives late tonight. The strongest
DCVA/cooling aloft and steep midlevel lapse rates related to the
approaching trough will remain behind the cold front. However, a
tightening height gradient, related strengthening deep shear, and
large-scale lift within an intensifying LLJ/WAA plume will spread
across the warm sector this evening and overnight. These processes
will destabilize, moisten and increase shear in low levels. Surface
dewpoints generally in the 60s F (greater southwestward) will
contribute to MLCAPE near 1000 J/kg from the Arklatex into at least southwestern TN, diminishing northeastward from there. A shallow,
neutral to stable near-surface thermal profile will be present
nocturnally, but may not preclude strong gusts or a tornado.
Substantially front-parallel flow aloft will lead to a dominant
quasi-linear mode with the frontal activity, but the marginal
hail/tornado threat should exist with any antecedent, persistent,
relatively discrete cells. Embedded LEWP/bowing configurations in
the frontal band will pose the greatest local gust potential.

..Edwards/Goss.. 12/17/2024

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ACUS01 KWNS 181253
SWODY1
SPC AC 181251

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0651 AM CST Wed Dec 18 2024

Valid 181300Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE TENNESSEE VALLEY REGION...

...SUMMARY...
Isolated damaging wind gusts and a brief tornado are possible into
early afternoon across parts of the Tennessee Valley region.

...Synopsis...
A continuing progressive pattern aloft will be dominated by two main
shortwave troughs: a trailing perturbation now over the coastal
Pacific Northwest, and a positively tilted one apparent in moisture-
channel imagery near a DBQ-STJ-P28-DHT axis. The latter will be the
main mid/upper-level convective influence this period, as it
elongates and tracks to near a PIT-LEX-ELD-GLS line by 00Z. The
southern part of the trough is progged to amplify and become less
positively tilted as it crosses the Mississippi Delta region
tonight, reaching northern GA, eastern AL and the western FL
Panhandle by 12Z.

At the surface, 11Z analysis showed a cold front across parts of northern/western KY, western TN, southern AR, and northeast/central/
southwest TX. By 00Z, the front should extend from a low over
northern NJ southwestward, roughly along the Blue Ridge, then over
northern GA to the FL Panhandle. By the end of the period, the cold
front should be off all the Atlantic Coast except central FL,
extending southwestward to the southern Gulf.

...TN and vicinity...
Isolated, damaging to marginally severe gusts and/or a brief tornado
are possible into the afternoon, mainly over portions of TN. A
near-frontal band of thunderstorms was ongoing from the Arklatex
region across the Mid-South, to central KY. Ahead of this activity,
a northward-narrowing corridor of 60s F surface dewpoints (and
related near-surface-based effective-inflow parcels) was evident,
supporting 250-750 J/kg MLCAPE from near MEM to northwest of BNA,
where the 12Z sounding still showed a stable boundary layer. See
SPC Mesoscale Discussion 2272 for near-term info.

Weak, continuing, preconvective theta-e advection, and perhaps a few
deg F of cloud-restrained diurnal warming, will offset modest
midlevel lapse rates enough to maintain and perhaps slightly
increase surface-based buoyancy eastward across TN through early/mid
afternoon. Although flow ahead of the QLCS that has not already
done so should veer to south-southwest or southwest, enough
hodograph enlargement will remain to support around 100-150 J/kg
0-500m SRH and 200-300 J/kg effective SRH, amid 35-45-kt
effective-shear magnitudes. As such, the main concern will arise
from episodic, embedded BOW/LEWP formations and accompanying
mesocirculations. The convective band should outpace the already
marginally unstable boundary layer by midafternoon.

..Edwards/Goss.. 12/18/2024

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ACUS01 KWNS 211252
SWODY1
SPC AC 211250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0650 AM CST Sat Dec 21 2024

Valid 211300Z - 221200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Isolated thunderstorms are possible this morning into early
afternoon across parts of coastal Oregon and northern California.

...Coastal OR/northern CA...
A potent mid to upper-level shortwave trough will move ashore the
northern CA/OR coast and continue northeastward into the southern
Canadian Rockies/northern Rockies vicinity through late tonight.
Weak thunderstorm activity embedded within a warm-air advection rain
shield will continue moving into the coastal range mountains this
morning before outrunning the inland penetration of scant
instability. The corridor of thunderstorms will probably shift
north along the coast into OR by midday into the early afternoon in
association with the mid-level cold pocket encroaching on the OR
coast. Elsewhere, quiescent weather or stable conditions will
preclude thunderstorm development over the remainder of the
contiguous United States.

..Smith/Goss.. 12/21/2024

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ACUS01 KWNS 222000
SWODY1
SPC AC 221959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0159 PM CST Sun Dec 22 2024

Valid 222000Z - 231200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast across the contiguous United
States through tonight.

...20Z Update...
Lightning flashes continue to be observed just offshore of the
northern CA coastline as a mid-level trough approaches the Pacific
Northwest. As the mid-level trough continues to advance toward the
coastline later this afternoon and evening, increased mid-level
cooling aloft will encourage at least isolated onshore thunderstorm development. As such, no changes have been made to the previous
forecast.

..Squitieri.. 12/22/2024

.PREV DISCUSSION... /ISSUED 1003 AM CST Sun Dec 22 2024/

...Northern CA/Pacific Northwest coast through tonight...
Lightning flashes have been observed this morning within a
baroclinic band roughly 150 mi off the northern CA coast, in
association with a midlevel shortwave trough that will move inland
later today into tonight. The potential for isolated lightning
flashes inland will begin this afternoon with elevated convection in
the warm conveyor belt across northwest CA/southwest OR. Other
isolated lightning flashes may also occur this evening into early
tonight along the WA coast as steeper low-midlevel lapse rates and
weak buoyancy spread inland.

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ACUS01 KWNS 231244
SWODY1
SPC AC 231242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0642 AM CST Mon Dec 23 2024

Valid 231300Z - 241200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not forecast through tonight across the
contiguous United States.

...Synopsis...
Water-vapor imagery this morning shows a mid-level trough over AZ
moving east and a northern stream trough over the Pacific Northwest.
The northern mid-level trough will latitudinally expand southward
into the central Rockies/south-central High Plains as a ridge
amplifies over the Interior West in its wake. As this occurs, a
partial phasing of mid-level trough over the Desert Southwest will
occur as it moves into the southern High Plains. Farther west, a
powerful upper trough will reach the WA/OR/northern CA coasts late
tonight. In the low levels, surface high pressure will influence
conditions over much of the Lower 48 states. Weak/ill-defined lower
pressure over central TX will facilitate southerly flow from the TX
coastal plain northward into the Red River Valley.

Weak 850-mb warm-air advection will likely persist through the
period across north TX into OK while a modest increase in moisture
eventually results in weak elevated instability. Isolated to widely
scattered showers and a few thunderstorms are possible tonight over
eastern OK and perhaps as far south as north TX.

..Smith/Goss.. 12/23/2024

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