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ACUS01 KWNS 130047
SWODY1
SPC AC 130045
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 PM CDT Sat Sep 12 2026
Valid 130100Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTH-CENTRAL PLAINS...
...SUMMARY...
Strong to severe storms capable of severe wind gusts and isolated
hail remain possible tonight across parts of the south-central
Plains.
...South-central Plains and vicinity...
Isolated strong to severe storms are ongoing this evening from
southwest KS into northwest OK and the TX Panhandle, with another
persistent storm cluster across eastern KS. Earlier storm
development across central/northwest OK was driven by very strong
heating in the vicinity of an outflow boundary, within a regime of
generally weak deep-layer flow/shear. This activity is expected to
generally weaken through late evening, due to the onset of nocturnal
cooling/stabilization. However, isolated hail and strong to severe
gusts will remain possible with any remaining storms through
mid/late evening.
Another surface boundary is located across southern KS, with moist
low-level easterly flow in place between this boundary and the
outflow boundary across OK. Short-term CAM guidance continues to
depict persistence of strong to locally severe storms through late
evening within this regime from southern KS into far northern OK and
perhaps southwest MO, potentially aided by a modest strengthening of
the nocturnal low-level jet. While this convection may tend to
become increasingly elevated with time, favorable lapse rates and
buoyancy and sufficient deep-layer shear (as depicted on the 00Z DDC
sounding) will support vigorous cells and perhaps a loosely
organized cluster, with potential for strong to severe gusts and
isolated hail.
See MCDs 2290 and 2291 for more information regarding the short-term
threats in this region.
..Dean.. 09/13/2026
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20260913T0047.txt
009
ACUS01 KWNS 122002
SWODY1
SPC AC 122000
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Sat Sep 12 2026
Valid 122000Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS...
...SUMMARY...
Isolated to scattered severe thunderstorms capable of producing
large to very large hail and severe/damaging winds may occur across
parts of the south-central Plains into the Ozarks this afternoon and
evening.
...20Z Update...
The SLGT Risk in the central/southern Plains was expanded
southwestward across parts of western OK. Here, visible satellite
imagery shows increasingly agitated boundary-layer cumulus and
isolated convective initiation along the western portion of a
remnant outflow boundary. Temperatures in the 102-104F range
along/south of the wind shift will support scattered severe wind
gusts with any clusters that evolve. Additionally, the 15-percent
hail probabilities were expanded westward into parts of southwest KS
and northwest OK. Given steep midlevel lapse rates accompanying an
EML (sampled by the 18Z DDC sounding), initial semi-discrete
supercells should pose a risk of scattered severe hail before
clustering occurs. Elsewhere, the previous forecast remains on track
and minimal changes were needed.
..Weinman.. 09/12/2026
.PREV DISCUSSION... /ISSUED 1135 AM CDT Sat Sep 12 2026/
...Central/Southern Plains to the Ozarks...
Scattered mainly elevated thunderstorms continue at midday across
the region, including the strongest/occasionally-severe storms
across southeast Nebraska into northeast Kansas that are occurring
near/just behind a southeastward-moving cold front. Some severe hail
will remain possible as these storms continue southeastward on the
edge of the primary instability reservoir.
This front, augmented by early day outflows, will otherwise serve as
a focus for more robust thunderstorm development this
afternoon/evening as well. With a rather moist low-level airmass
forecast to be present along/south of the front, current
expectations are for a narrow zone of moderate to strong instability
(MLCAPE 2000-3500 J/kg) to develop this afternoon from the eastern
Oklahoma/Texas Panhandles across southern Kansas and northern
Oklahoma. Weak low-level winds will veer to west-northwesterly and
strengthen some with height through mid/upper levels, supporting
around 30-40 kt of deep-layer shear and updraft organization. While
large-scale ascent will remain fairly weak/nebulous across the
southern/central Plains, most guidance shows at least isolated
robust thunderstorm development along the front by 21-23Z as
convective temperatures are reached.
Any sustained supercells would pose a threat for large to very large
hail, with steep mid-level lapse rates and ample instability in the
hail-growth zone supporting potential for 2+ inch
diameter hail on an isolated basis. Somewhat higher-based convection
is expected from the eastern Oklahoma/Texas Panhandles into
southwest/south-central Kansas and northern Oklahoma, where a very
well-mixed boundary layer with steep low/mid-level lapse rates
will promote an environment that supports severe-caliber downdraft
winds. Some gusts could exceed 75 mph. A degree of storm clustering
could occur into this evening.
...Upper Ohio Valley...
A regional pocket of relatively cloud-free skies at midday will
contribute to filtered diurnal heating and moderate instability
across the region. Thunderstorms will further increase in coverage
and intensity through the afternoon, aided by forcing for ascent
associated with an approaching weak mid-level shortwave trough.
While mid-level lapse rates will remain poor, sufficient deep-layer
shear coupled with modest steepening of low-level lapse rates
suggest some risk for occasional damaging winds with any loosely
organized clusters/line segments that develop.
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20260912T2002.txt
358
ACUS01 KWNS 121637
SWODY1
SPC AC 121635
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1135 AM CDT Sat Sep 12 2026
Valid 121630Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS...
...SUMMARY...
Isolated to scattered severe thunderstorms capable of producing
large to very large hail and severe/damaging winds may occur across
parts of the south-central Plains into the Ozarks this afternoon and
evening.
...Central/Southern Plains to the Ozarks...
Scattered mainly elevated thunderstorms continue at midday across
the region, including the strongest/occasionally-severe storms
across southeast Nebraska into northeast Kansas that are occurring
near/just behind a southeastward-moving cold front. Some severe hail
will remain possible as these storms continue southeastward on the
edge of the primary instability reservoir.
This front, augmented by early day outflows, will otherwise serve as
a focus for more robust thunderstorm development this
afternoon/evening as well. With a rather moist low-level airmass
forecast to be present along/south of the front, current
expectations are for a narrow zone of moderate to strong instability
(MLCAPE 2000-3500 J/kg) to develop this afternoon from the eastern
Oklahoma/Texas Panhandles across southern Kansas and northern
Oklahoma. Weak low-level winds will veer to west-northwesterly and
strengthen some with height through mid/upper levels, supporting
around 30-40 kt of deep-layer shear and updraft organization. While
large-scale ascent will remain fairly weak/nebulous across the
southern/central Plains, most guidance shows at least isolated
robust thunderstorm development along the front by 21-23Z as
convective temperatures are reached.
Any sustained supercells would pose a threat for large to very large
hail, with steep mid-level lapse rates and ample instability in the
hail-growth zone supporting potential for 2+ inch
diameter hail on an isolated basis. Somewhat higher-based convection
is expected from the eastern Oklahoma/Texas Panhandles into
southwest/south-central Kansas and northern Oklahoma, where a very
well-mixed boundary layer with steep low/mid-level lapse rates
will promote an environment that supports severe-caliber downdraft
winds. Some gusts could exceed 75 mph. A degree of storm clustering
could occur into this evening.
...Upper Ohio Valley...
A regional pocket of relatively cloud-free skies at midday will
contribute to filtered diurnal heating and moderate instability
across the region. Thunderstorms will further increase in coverage
and intensity through the afternoon, aided by forcing for ascent
associated with an approaching weak mid-level shortwave trough.
While mid-level lapse rates will remain poor, sufficient deep-layer
shear coupled with modest steepening of low-level lapse rates
suggest some risk for occasional damaging winds with any loosely
organized clusters/line segments that develop.
..Guyer/Wendt.. 09/12/2026
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20260912T1637.txt
112
ACUS01 KWNS 121250
SWODY1
SPC AC 121248
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Sat Sep 12 2026
Valid 121300Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL/SOUTHERN PLAINS...
...SUMMARY...
Isolated to scattered severe thunderstorms capable of producing
large to very large hail and severe/damaging winds may occur across
parts of the central/southern Plains into the Ozarks this afternoon
and evening.
...Central/Southern Plains into the Ozarks...
Mainly elevated thunderstorms have persisted overnight into the
early morning across southern NE into eastern KS/western MO, aided
by a modest low-level jet. This activity will probably tend to
weaken through the remainder of the morning, but some recent
guidance suggests additional thunderstorms developing along its
outflow across southern KS/northern OK over the next few hours. If
this development occurs, it would potentially complicate
destabilization and severe potential later today. Recent surface
observations also show a fairly strong cold front draped from
eastern CO into KS and northwest MO. This boundary will likely serve
as a focus for robust thunderstorm development this
afternoon/evening as well. With a rather moist low-level airmass
forecast to be present along/south of the front, current
expectations are for a narrow zone of moderate to strong instability
(MLCAPE 2000-3500 J/kg) to develop this afternoon from the eastern
OK/TX Panhandles into southern KS/northern OK. Weak low-level winds
will veer to west-northwesterly and strengthen some with height
through mid/upper levels, supporting around 30-40 kt of deep-layer
shear and updraft organization. While large-scale ascent will remain
fairly weak/nebulous across the southern/central Plains, most
guidance shows at least isolated robust thunderstorm development
along the front by 21-23Z as convective temperatures are reached.
While there is still uncertainty regarding convective evolution and
persistence of ongoing thunderstorms this morning, some signal
exists in most recent short-term guidance that isolated to scattered
convection will form along much of the length of the front later
today in a rather favorable environment to support severe
thunderstorms. Any sustained supercells would pose a threat for
large to very large hail, with steep mid-level lapse rates and ample
instability in the hail-growth zone supporting potential for 2+ inch
diameter hail on an isolated basis. Somewhat higher-based convection
also appears probable from the eastern OK/TX Panhandles into parts
of southwest/south-central KS and northern OK, where a very
well-mixed boundary layer with steep low/mid-level lapse rates
should promote an environment that supports scattered severe
downdraft winds. Some gusts could exceed 75 mph. The potential for
clustering this afternoon and evening remains unclear, but some
chance for at least isolated severe/damaging winds may persist into
much of OK and the Ozarks, dependent on upstream convective
evolution in KS/western MO.
...Upper Ohio Valley...
A narrow corridor of filtered diurnal heating and related moderate
instability should develop across parts of the upper OH Valley this
afternoon between denser clouds and precipitation occurring across
OH, and a stationary boundary to the east. Thunderstorms will
gradually increase in coverage and intensity through the afternoon,
aided by forcing for ascent associated with an approaching weak
mid-level shortwave trough. While mid-level lapse rates will remain
poor, sufficient deep-layer shear coupled with modest steepening of
low-level lapse rates suggest some risk for occasional damaging
winds with any loosely organized clusters/line segments that can
form.
..Gleason/Lyons.. 09/12/2026
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20260912T1250.txt
151
ACUS01 KWNS 120525
SWODY1
SPC AC 120524
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1224 AM CDT Sat Sep 12 2026
Valid 121200Z - 131200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE CENTRAL AND SOUTHERN PLAINS...OZARK PLATEAU...AND UPPER OHIO
VALLEY...
...SUMMARY...
Widely scattered severe storms capable of large hail up to two
inches and damaging wind gusts appear possible over portions of the
central and southern Plains into the Ozark Plateau on Saturday into
Saturday night. Isolated occurrences of damaging wind gusts may also
occur over portions of the upper Ohio Valley Saturday afternoon.
...Synopsis...
A belt of enhanced mid/upper-level flow will persist over the
north-central U.S., downstream from a vigorous upper low moving into
the Pacific Northwest. Meanwhile, a lower-latitude trough over the
lower OH and lower MS Valleys Saturday morning is forecast to weaken
while progressing through the OH and TN Valleys. At the surface, a
cold front will advance through the upper Great Lakes with the
trailing extension of the boundary pushing south through the lower
MO Valley and central Plains before linking with a surface low over
the southern High Plains.
...Central and Southern Plains into the Ozark Plateau...
Persistent capping across the pre-frontal warm sector and generally
weak forcing for ascent lead to considerable uncertainty in
thunderstorm evolution through the forecast period. A number of the
00Z models (both convection-allowing and parameterized) indicate
areas of thunderstorms ongoing at 12Z Saturday over the central
Plains within a zone of modest warm advection and moisture transport
associated with a weakening low-level jet. One possible scenario is
for the continued southeast movement of the early-day storms through
eastern KS and southwest MO into portions of OK and AR by afternoon,
where a hot and moderate to strongly unstable air mass (i.e., MLCAPE
up to 2000-3000 J/kg) is forecast to develop. The instability
combined with around 30 kt of deep-layer shear would support
organized cold pool development in that scenario with an associated
risk for damaging wind gusts and large hail.
Renewed storm development appears possible from late morning into
afternoon from north of the front in south-central and southeast NE
to along or ahead of the front in northeast KS. Up to 40 kt of
deep-layer shear will coincide with the northern extension of the
stronger instability mentioned above to support supercell storm
modes with an associated risk for large hail up to two inches and
damaging wind gusts.
A separate thunderstorm regime may also evolve by mid to late
afternoon over the eastern OK and TX Panhandles into western OK in
the vicinity of the surface low and southward-sagging front.
Forecast soundings indicate a deep, well-mixed boundary layer, which
will be supportive of a few severe wind gusts and isolated large
hail.
Confidence in any of the above scenarios/regimes remains too low to
include Slight Risk wind and hail probabilities with this forecast.
A categorical upgrade is possible in subsequent Day 1 outlooks once
finer-scale details become more clear.
...Upper Ohio Valley...
A spatially narrow corridor of stronger heating and resultant
instability (MLCAPE up to 1500-2000 J/kg) is forecast to develop
during the afternoon between denser clouds and precipitation to the
west, and a backdoor front/stationary boundary to the east.
Thunderstorms are expected to increase in coverage and intensity
through the afternoon within the instability axis, aided by
increased forcing for ascent associated with the approaching
mid-level trough. While mid-level lapse rates are expected to remain
relatively weak, deep-layer shear increasing to 30-35 kt coupled
with steepening low-level lapse rates suggests the potential for
some storm organization with the primary hazard being damaging wind
gusts. Backed low-level winds in the vicinity of the surface front
will boost low-level shear slightly and a brief tornado cannot be
ruled out as mature storms approach the frontal zone from the west.
..Mead/Halbert.. 09/12/2026
$$
File: /home/ldm/var/data/BY_SOURCE/KWNS/ACUS01/20260912T0525.txt
