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DAY48SVR: Nws Storm Prediction Center Norman Ok

From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Mon Jan 3 09:48:09 2022

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ACUS48 KWNS 030948
SWOD48
SPC AC 030946

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CST Mon Jan 03 2022

Valid 061200Z - 111200Z

...DISCUSSION...
West-northwesterly mid-level flow is forecast on Thursday across
much of the continental United States. At the surface, high pressure
will be entrenched across the central and eastern states. This
feature is forecast to move eastward into the western Atlantic by
Saturday which should allow for moisture return onto the Texas
Coastal Plains. Thunderstorms will be possible along the northern
edge of this moist airmass Saturday afternoon and evening. Moisture
return could continue into the south-central U.S. Saturday night
into Sunday as a cold front approaches quickly from the northwest,
but model spread concerning that scenario is large. Thunderstorms
will again be possible ahead of the front Sunday afternoon and
evening from the Arklatex into the lower to mid Mississippi Valley.
Although a severe threat could develop on Sunday, uncertainty at
this range is substantial. The front is currently forecast to move
into the western Gulf of Mexico on Monday ending the potential for thunderstorms along the Gulf Coast.

..Broyles.. 01/03/2022

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From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Tue Jan 4 09:10:15 2022

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ACUS48 KWNS 040910
SWOD48
SPC AC 040908

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0308 AM CST Tue Jan 04 2022

Valid 071200Z - 121200Z

...DISCUSSION...
A large upper trough is expected to be over the eastern CONUS on
Friday/D4, and is forecast to move out of the Northeast on
Saturday/D5. An associated area of high pressure will move from the
MS Valley to the Mid Atlantic during the same period, with low-level
moisture return occurring late Saturday/D5 into Sunday/D6 across the
Southeast as a positive-tilt upper trough moves from the Four
Corners area across the southern Plains.

At least a low-end severe threat may develop around Sunday/D7 across
the lower MS Valley as mid to upper 60s F dewpoints spread north
ahead of a cold front. At this time, it appears the positive-tilt
nature of the upper trough and the fast/potentially undercutting
nature of the cold front will preclude any significant severe
potential. However, front-parallel winds aloft and MUCAPE of
500-1000 J/kg may support some damaging wind potential.

The aforementioned shortwave trough will then become absorbed into a larger-scale upper trough which is forecast to amplify across much
of the Great Lakes and Northeast, with high pressure rapidly
stabilizing much the eastern half of the CONUS.

..Jewell.. 01/04/2022

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From COD Weather Processor@1:2320/105 to wx-storm@lists.illinois.edu on Wed Jan 5 09:34:21 2022

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ACUS48 KWNS 050934
SWOD48
SPC AC 050932

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0332 AM CST Wed Jan 05 2022

Valid 081200Z - 131200Z

...DISCUSSION...
A positive-tilt upper trough is forecast to move across the Rockies
on Saturday/D4, emerging into the Plains on Sunday/D5. This will
occur as a strong upper trough amplifies across the northern Plains
and Great Lakes. The initial trough will quickly become absorbed by
the larger amplification, which will continue through Monday/D6
before departing the northeastern states after Tuesday/D7.

During the Saturday/D4 to Sunday/D5 period, southerly winds will
result in increasing moisture from eastern TX across the lower MS
Valley, and widespread rain and thunderstorms are forecast. Mid to
upper 60s F dewpoints will contribute to 500-1000 J/kg MUCAPE ahead
of a developing cold front. This front will especially surge on
Sunday/D5, and will likely undercut convection as it develops. While strengthening mid/upper flow will lead to favorable shear,
predictability for anything more than low-end severe is low given
the aforementioned weak instability and surging cold front. By
Monday/D6, the front will clear the southeastern states, resulting
in drying conditions.

..Jewell.. 01/05/2022

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From COD Weather Processor @1:2320/107 to All on Sat Aug 15 07:54:28 2026

ACUS48 KWNS 150754
SWOD48
SPC AC 150752

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 AM CDT Sat Aug 15 2026

Valid 181200Z - 231200Z

...DISCUSSION...
...Day 4/Tue - NE/IA and vicinity...

An upper trough over the Great Lakes/Midwest will deepen on Tuesday,
with increasing northwesterly flow aloft overspreading portions of
the northern/central Plains to the Mid/Upper MS Valley. Rich
boundary layer moisture will be in place ahead of a south/southeastward-developing surface front. There is some
uncertainty regarding possible early-day convection of cloud debris
across parts of the region. However, most guidance suggests a
corridor of strong instability will develop by afternoon. Supercell
wind profiles will support organized cells, possibly growing upscale
with time along the surface front. Initially, a large hail risk
could transition toward more of a damaging wind risk, particularly
if upscale growth does occur as storms develop southeast through the
evening.

...Days 5-8...

Upper trough will deepen across the eastern U.S. and persist into
the weekend. Meanwhile, an amplified upper ridge will remain in
place across the western U.S. A surface front will sag south and
east on Wednesday and Thursday as upper trough deepens and surface
high pressure builds over the Great Lakes. Some isolated severe risk
could emerge over the Mid-South/TN valley toward the Eastern
Seaboard in response, but deep-layer flow will remain weak and
low-level winds mostly parallel to the surface front, limiting a
more substantial/organized risk.

..Leitman.. 08/15/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sun Aug 16 07:54:40 2026

ACUS48 KWNS 160754
SWOD48
SPC AC 160752

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 AM CDT Sun Aug 16 2026

Valid 191200Z - 241200Z

...DISCUSSION...
...Days 4-5/Wed-Thu -- Mid-South to Mid-Atlantic...

An amplifying upper pattern is expected mid-week into the weekend,
with troughing developing across the eastern half of the CONUS and
an upper riding across the western half. As the upper trough digs
across the eastern U.S., some severe potential could develop across
the Mid-South into the southern Mid-Atlantic on Days 4-5/Wed-Thu.
Building surface high pressure across the Great Lakes and stalled
upper troughing will result in a slowly sagging surface front arcing
across the region. With a very moist airmass in place, thunderstorms
are possible, and at least isolated damaging winds could accompany
this activity. However, potential appears too limited at this time
for 15 percent probabilities at the time scale.

...Days 7-8/Sat-Sun -- Northern/Central Plains...

Some severe potential could develop across the Plains during the
weekend on the eastern periphery of the amplified upper ridge.
Northwesterly flow aloft will remain enhanced across the region as
southerly low-level flow on the back side of the Great Lakes surface
high transports rich boundary layer moisture across the region. It
is uncertain if capping will preclude thunderstorm development, but
if any shortwave impulses migrate through northwesterly flow aloft,
some severe risk could develop.

..Leitman.. 08/16/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Mon Aug 17 13:45:52 2026

ACUS48 KWNS 170750
SWOD48
SPC AC 170748

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0248 AM CDT Mon Aug 17 2026

Valid 201200Z - 251200Z

...DISCUSSION...
An amplified upper pattern will persist during the Day 4-8/Thu-Mon
period. An upper trough will remain over the eastern U.S. while
strong upper ridging spreads from the western U.S. toward the Plains
late in the period. This pattern will result in moderate
northwestern flow aloft across portions of the Plains into the
Midwest. Beneath northwesterly flow aloft and on the eastern
periphery of upper ridging, a seasonally moist airmass will be in
place from the Mid/Lower MO Valley into the Upper/Middle MS Valley.
Some severe potential could develop over these areas through the
period. However, capping may limit this potential, and with no
notable features fostering focused large-scale ascent, uncertainty
is too high to include 15 percent severe probabilities at this time.

..Leitman.. 08/17/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Tue Aug 18 08:26:20 2026

ACUS48 KWNS 180826
SWOD48
SPC AC 180824

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0324 AM CDT Tue Aug 18 2026

Valid 211200Z - 261200Z

...DISCUSSION...
For the Fri/D4 to Tue/D8 period, an upper ridge is forecast to
expand from the Four Corners states into the Southern Plains, with
northwest flow aloft over the Northern Plains shifting east across
Midwest and into the Northeast.

On Fri/D4, scattered storms may occur across the Central Plains and
Cornbelt, with areas of moisture and instability beneath the 30-40
kt northwest flow regime favor scattered hail or strong wind gusts. Predictability is low due to the likelihood of ongoing storms or
convective systems early in the day, which may affect air mass
quality and effective boundary positioning. However, the NE/KS/IA/MO
region appears to be the most likely area for an eventual risk area.

Also on Fri/D4, storms are again expected over parts of the Mid
Atlantic to Carolinas, where 25 kt southwest flow in the midlevels
and a surface trough will support scattered storm clusters producing
locally damaging gusts. Areas of ongoing storms or outflows from the
previous day's convection may have an impact here as well as far as
the most favorable zones for additional severe storms.

There may also be some potential on Sat/D5 to Sun/D6 over parts of
the Mid Atlantic as cooling aloft with an upper trough moves across
the area. Timing of this trough will be critical, as will the
movement of the associated cold front.

..Jewell.. 08/18/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Wed Aug 19 08:30:38 2026

ACUS48 KWNS 190830
SWOD48
SPC AC 190828

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0328 AM CDT Wed Aug 19 2026

Valid 221200Z - 271200Z

...DISCUSSION...
For the Sat/D4 to Wed/D8 period, an upper ridge will persist from
the Southern Plains into the Southwest, while various shortwave
troughs affect the northern Plains, Great Lakes, and Northeast. The
primary trough amplification will occur from the Upper MS
Valley/Great Lakes on Sat/D4 into the Northeast through Mon/D6, with
moisture and instability supportive of strong storms generally
persisting over parts of the Southeast and Mid Atlantic. Shear will
remain weak over the East on Sat/D4, with areas of storms producing
strong gusts, perhaps marginal/isolated severe. By Sun/D5, strong
winds and cooling aloft will move across the Mid Atlantic and
Northeast, though antecedent precipitation will affect the warm
sector, as will veering low-level winds. Frontal timing will depend
on the upper trough speed, and overall predictability is low for
Sun/D5.

To the west, daily corridors of thunderstorms are also likely over
parts of the central to northern Plains, with northwest flow
strongest on Sat/D4 and weakening into D5/D6. At least marginal
risk/low probabilities are likely in later outlooks for isolated
wind/hail.

..Jewell.. 08/19/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Thu Aug 20 08:31:18 2026

ACUS48 KWNS 200830
SWOD48
SPC AC 200829

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0329 AM CDT Thu Aug 20 2026

Valid 231200Z - 281200Z

...DISCUSSION...
An upper trough will move slowly across the Northeast Sun/D4 into
Mon/D5, with thunderstorms likely ahead of a cold front. This front
will likely push offshore on Mon/D5 as a surface low ejects
northward across Quebec. A moist air mass will remain ahead of the
front across the Mid Atlantic and into New England, though ongoing
rain and thunderstorms reduce predictability as far as how unstable
it will become on Sun/D4. Also mitigating overall severe risk
appears to be relatively modest low-level wind speeds, with 10-20 kt
at 850 mb. These areas will be monitored for possible low severe
probabilities in the coming days.

To the west, low severe probabilities are possible over parts of the
northern High Plains, as a small but progressive shortwave trough
moves out of the Northwest and across the northern Rockies atop the
upper ridge. West to northwest winds across the northern High Plains
combined with a lee trough and ribbon of 2000 J/kg MUCAPE should
support at least isolated hail/wind activity, perhaps from eastern
MT into the Dakotas.

Additional storm potential, generally low-end, will be possible
Tue/D6 into Wed/D7 over much of the Midwest to Great Lakes, though predictability is quite low in forecasting the track of the northern
wave, which may begin phasing with a developing upper low over
Ontario.

..Jewell.. 08/20/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Fri Aug 21 08:56:24 2026

ACUS48 KWNS 210856
SWOD48
SPC AC 210854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Fri Aug 21 2026

Valid 241200Z - 291200Z

...DISCUSSION...
A mid-level trough will move across the Northeast on Monday and the
surface front will be mostly offshore, reducing the severe weather
threat. As this trough departs, ridging will build across the
Rockies. This will eventually set up a pattern featuring individual
mid-level shortwave troughs within northwesterly flow from the
northern Plains to the Midwest. Some severe weather will likely
occur with mid-level shortwave troughs within this flow, but these
details likely will not become more clear until the short term.

Model consensus indicates a stronger mid-level shortwave trough
traversing the Pacific Northwest on D7/Thursday. This pattern would
be favorable for some severe weather threat across Montana, but at
this time, it appears moisture will stay farther east. Therefore, no
severe weather is anticipated.

..Bentley.. 08/21/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sat Aug 22 07:44:26 2026

ACUS48 KWNS 220744
SWOD48
SPC AC 220742

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0242 AM CDT Sat Aug 22 2026

Valid 251200Z - 301200Z

...DISCUSSION...
Overall, the long range pattern will feature a ridge centered over
the southern High Plains which may shift slightly west through the
period. Some severe weather may occur within the northwesterly flow
pattern from the northern Plains to the Ohio Valley Tuesday/D4 to
Thursday/D6, but confidence is not high enough for probabilities at
this time. There is an emerging signal for a seasonably strong high
pressure to build into the eastern CONUS and shunt most of the
richer low-level moisture to the Gulf Coast states. If this occurs,
a relative lull in severe weather potential would exist from the
Mid-Atlantic and Northeast to the Upper Midwest into next weekend.

..Bentley.. 08/22/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sun Aug 23 08:41:00 2026

ACUS48 KWNS 230840
SWOD48
SPC AC 230838

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0338 AM CDT Sun Aug 23 2026

Valid 261200Z - 311200Z

...DISCUSSION...
...D4/Wednesday to D6/Friday...
A mid-level trough will amplify across the Great Lakes region while
the mid-level ridge maintains its amplitude across the Rockies.
Within this pattern, some severe weather potential may exist as a
cold front moves from the Great Lakes to the Northeast. However, the
signal is not that strong and thus, it is unclear if more than an
isolated threat will exist; but the evolution of this front and the
instability associated with it will be monitored.

...D7/Saturday to D8/Sunday...
There is still a fair amount of uncertainty with the evolution of
the pattern by next weekend, but a general trend toward flattening
of the upper-level ridge is apparent in the deterministic, AI, and
ensemble guidance next weekend. This includes moderate flow within
the zonal region across the central/northern Plains and into the
Upper Midwest. This period will need to be watched closely as strong instability and moderate shear appear to overlap across a relatively
broad region, which should support diurnal thunderstorm activity
given the flattening of the ridge. The specific timing/location of
these threats will depend on evolution of the pattern and the
embedded shortwave troughs within the flow. However, it is worth
noting that the EC-AIFS and the AIGFS both have a signal for a more consolidated mid-level shortwave trough moving across the northern
Plains on Sunday/D8, which has also been consistently shown by the
EC-AIFS for the past 4 runs. If this trend continues, there may be opportunities for probabilities to be added in later outlooks.

..Bentley.. 08/23/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Mon Aug 24 09:01:06 2026

ACUS48 KWNS 240900
SWOD48
SPC AC 240859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Mon Aug 24 2026

Valid 271200Z - 011200Z

...DISCUSSION...
A strong mid-level ridge will be centered over the Rockies on
Thursday with a broad trough centered across the Great Lakes. The
ridge will break down over the weekend with a more zonal flow with
embedded shortwave troughs extending from the Northwest to the
northern Plains and into the Northeast. Beyond this weekend,
guidance differs on the evolution of the pattern with considerable
uncertainty.

...D7/Sunday to D8/Monday - Northern Plains...
Guidance continues to consolidate around an unseasonably strong
mid-level shortwave trough across the northern Plains into the Upper
Midwest on Sunday and Monday. There is still some spread around the
timing of this trough and also the degree of destabilization ahead
of it. However, despite these timing differences, a moderately
strong signal for an increasing severe weather threat in this period
appears to be emerging as a trough with a consistent convective
signal is shown by the ECMWF and GFS and also by the AI-GFS and
AI-ECMWF. Ensemble guidance shows a flattened ridge with a mid-level
jet streak across this region during the same timeframe.
Surprisingly, AI/ML guidance shows very little signal for a severe
threat across this region. Analysis of individual ensemble members
suggests this is likely reflective of the uncertainty in timing and
location of this trough and greater spread among the ensemble
guidance. Nonetheless, the potential for an organized severe weather
threat across the northern Plains and/or Upper Midwest late this
weekend into early next week appears to be increasing. If guidance
continues to consolidate with decreasing spread about the timing of
the trough, severe weather probabilities may eventually be needed.

..Bentley.. 08/24/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Tue Aug 25 08:30:18 2026

ACUS48 KWNS 250829
SWOD48
SPC AC 250827

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0327 AM CDT Tue Aug 25 2026

Valid 281200Z - 021200Z

...DISCUSSION...
Severe weather is possible across the northern Plains into the Upper
Midwest starting Day 4/Friday and continuing through the weekend.
The specific evolution remains unclear with quite a range of
ensemble solutions at this time. Nonetheless, expect severe weather
somewhere within this broad region each day.

...Day4/Friday...
As the upper-level ridge flattens on Friday, lee troughing will
develop across the northern High Plains. Moderate to strong
instability is forecast to develop across the western Dakotas ahead
of this lee trough. Any weak mid-level shortwave trough to provide a
focus for this threat remains nebulous. Therefore, the location of
any surface features remains unclear and thus, it is difficult to
highlight a more specific region with a greater severe weather
probability at this time.

...Day5/Saturday...
Severe weather may be possible across portions of the Upper Midwest
on Saturday, but this threat will be somewhat dependent on the
location and intensity of Day 4 convection.

...Day6/Sunday...
The ECMWF and AI-ECMWF remain relatively consistent showing a trough
traversing the northwest on Saturday and emerging across the
northern Plains on Sunday. Meanwhile, the GFS and AI-GFS have
trended more progressive, and the individual GEFS members show
substantial spread in the upper-level pattern for Sunday/Day6. The
relative consistency in timing and location of the upper-level
trough from the ECMWF build confidence for this solution. However,
even the ECMWF and AI-ECMWF trended slightly less amplified with
this trough. Therefore, the combination of large spread in the upper
pattern from GEFS members and a slightly deamplified trend from the
ECMWF provide enough uncertainty to avoid adding probabilities at
this time.

..Bentley.. 08/25/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Wed Aug 26 08:44:10 2026

ACUS48 KWNS 260843
SWOD48
SPC AC 260842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Wed Aug 26 2026

Valid 291200Z - 031200Z

...DISCUSSION...
...D4/Saturday - Northern Plains to Upper Midwest...
A mid-level ridge will move slowly east across the Plains with
slight suppression through the day. A lee trough will consolidate
into a surface low across the northern Plains through the day
Saturday. Ahead of this surface low, strong instability is forecast
across South Dakota and vicinity. Despite the favorable environment
across this region, primary forcing will be focused on the nose of
the low-level jet across Iowa and into Wisconsin, well east of the
greatest instability and near the Canadian border. Therefore,
limited storm coverage precludes severe weather probabilities at
this time, but given the favorable environment, it will need to be
monitored closely.

...D5/Sunday - North Dakota and Vicinity...
A mid-level shortwave trough will move from the Pacific Northwest to
the northern Plains Saturday/D4 and Sunday/D5. 00Z guidance has come
into fairly consistent agreement with the location and amplitude of
this trough across eastern Montana at 00Z Sunday evening. However,
there is considerable disagreement with the degree of
destabilization across North Dakota, where forcing will be greatest.
The GFS dry bias across most of the Plains has severely lessened the instability. However, despite this challenge, it is apparent that
most of the instability significantly southeast of the upper-level
forcing. The GFS-Para seems to have a more realistic handle on
low-level moisture/instability magnitude but it also shows a
significant disconnect between where this instability is located and
the deeper forcing.

The deterministic ECMWF forecast shows a potentially significant
severe weather event across North Dakota with strong instability and
shear ahead of a robust convective QPF signal. This is supported by
the AI-ECMWF which shows a similar evolution. However, the
EC-ensemble mean of instability shows at least some trend toward the
GEFS with primary instability southeast of the best forcing.

It is also worth noting that the wave is forecast to eject across
North Dakota relatively late (~06Z) which may be a somewhat limiting
factor to a greater threat. This potential timing disconnect,
combined with some hint of limited overlap between the greatest
instability and the primary upper forcing, cast enough uncertainty
to preclude severe weather probabilities at this time. However, it
is worth noting that if a solution similar to the ECMWF
materializes, a significant severe weather event is possible.

...D6 and Beyond...
By early next week, the primary mid-level ridge appears to center
around the southern Appalachians with broad southwesterly flow from
the Southwest to the Great Lakes. Within this area of southwesterly
flow, multiple embedded mid-level shortwave troughs are forecast. Predictability of these smaller scale features is relatively low at
this range, but some continued severe weather threat will likely
persist around the periphery of the ridge from the Plains to the
Great Lakes and potentially into the Northeast.

..Bentley.. 08/26/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Thu Aug 27 08:00:42 2026

ACUS48 KWNS 270800
SWOD48
SPC AC 270758

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 AM CDT Thu Aug 27 2026

Valid 301200Z - 041200Z

...DISCUSSION...
...D4/Sunday - Northern Plains...
Some severe weather is possible across the northern Plains on
Sunday, but details remain unclear. The primary mid-level shortwave
trough and associated large-scale ascent is expected to traverse
northern Montana and North Dakota. However, the greater instability
is focused farther southeast across eastern South Dakota and
southwest Montana. The ECMWF shows enough instability developing
farther north into south-central North Dakota to support some severe
weather threat. The uncertainties regarding destabilization and
storm coverage preclude severe weather probabilities at this time.

...D5 and Beyond...
The forecast next week features multiple mid-level shortwave troughs
and considerable uncertainty with the timing of these features.
However, there is a larger scale trend toward a ridge building
across the Plains with northwesterly flow from the Upper Midwest to
the Mid-Atlantic/New England. Moderate to strong instability along
this corridor will support some severe weather potential next week.
However, specific areas of greater severe weather potential will
depend on the timing and amplitude of embedded mid-level shortwave
troughs. Therefore, no probabilities can be added at this time.

..Bentley.. 08/27/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Fri Aug 28 08:51:48 2026

ACUS48 KWNS 280851
SWOD48
SPC AC 280849

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CDT Fri Aug 28 2026

Valid 311200Z - 051200Z

...DISCUSSION...
An upper ridge will meander eastward across the central and eastern
CONUS through the week, with multiple mid-level shortwave troughs
and other smaller embedded impulses poised to pivot around the ridge
and traverse the northern Plains to the Mid-Atlantic. Several days
of at least scattered strong to severe thunderstorms are expected
along the periphery of the upper ridge as appreciably strong
mid-level flow overspreads a seasonably moist boundary layer,
especially during the middle of the week. By the end of the week,
appreciable instability builds back into the northern Plains and
upper MS Valley, but predictability is too low to ascertain any
localized severe potential this far in advance.

...OH Valley to the Mid-Atlantic and southern New England...
The strongest signal for severe thunderstorms currently exists for
Days 5-6 (Tuesday-Wednesday). Guidance differs on the details
regarding placement and timing of mid-level troughs/impulses on Day
5 (Tuesday), though severe thunderstorms will probably develop
somewhere between the eastern Great Lakes to the Eastern Seaboard.
Once details become clearer on where storm development is most
likely, 15 percent severe probabilities will likely be introduced.

For Day 6 (Wednesday), there is a general consensus among
medium-range guidance that at least one impulse will traverse the
eastern Great Lakes to the Mid-Atlantic/southern New England
corridor. A 50+ kt mid-level northwesterly 500 mb jet will
overspread mid 60s F surface dewpoints, yielding both 1500+ J/kg
MLCAPE and 40-50 kts of effective bulk shear amid a convective
signal. As such, a 15 percent severe area has been introduced for
Wednesday where these aforementioned ingredients best overlap.

..Squitieri.. 08/28/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sat Aug 29 08:57:46 2026

ACUS48 KWNS 290857
SWOD48
SPC AC 290855

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Sat Aug 29 2026

Valid 011200Z - 061200Z

...DISCUSSION...
Medium range guidance consensus depicts a persistent ridge fortified
across the central CONUS through the Days 4-8 (Tuesday-Saturday)
period. Multiple mid-level shortwave troughs and smaller scale
impulses will pivot around the broader upper ridge and traverse the
Pacific Northwest to northern Plains, Great Lakes, and Northeast
through the week. The best chance for rounds of organized strong to
severe thunderstorms will be with impulses overspreading a moist
boundary layer from the Upper MS Valley to the southern New England/Mid-Atlantic regions. Details regarding the timing and
placement of some of these impulses varies among medium-range
guidance, rendering predictability too low for several potential
severe scenarios.

...Days 4-7 (Tuesday-Friday) - Northeast/Mid-Atlantic...
The Northeast to Mid-Atlantic will experience the east-northeast
periphery of the aforementioned upper ridge, with multiple impulses
expected to overspread the region through the middle of the week. At
least isolated to scattered severe thunderstorms are expected each
day Tuesday-Friday. At the moment, medium range guidance consensus
shows the strongest signal in a mid-level impulse impinging on
southern New England and the Mid-Atlantic on Day 5/Wednesday, where
severe probabilities have been maintained.

Guidance also depicts these same regions to have adequate vertical
wind shear and instability Tuesday and Thursday, perhaps even
extending into Day 7/Friday. Like Wednesday, several members of
medium range ML/AI generated guidance also has severe probabilities
over these regions Days 4-7. Unlike Wednesday though, deterministic
medium range guidance varies in place and time of the more subtle
impulses expected to support severe weather over the Northeast. It
is acknowledged that severe probabilities will likely be needed in
the future. However, probabilities have been withheld outside of
Wednesday out of prudence given the degree of changes in forecast
details expected in the coming days.

..Squitieri.. 08/29/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sun Aug 30 08:39:22 2026

ACUS48 KWNS 300839
SWOD48
SPC AC 300837

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0337 AM CDT Sun Aug 30 2026

Valid 021200Z - 071200Z

...DISCUSSION...
An upper ridge will remain centered over the TN Valley/central
Appalachians through the end of the week before retrograding
westward toward the Plains by next weekend. Multiple mid-level
impulses and shortwave troughs will traverse the upper ridge this
week before upper troughing dominates the Interior West toward the
end of the extended forecast period. The best chances for severe
thunderstorms will be with the aforementioned impulses traversing
the ridge over the Great Lakes to the East Coast, particularly
during the middle of the week.

...Days 4-6 (Wednesday-Friday) - Northeast to Mid-Atlantic...
Severe probabilities have been maintained for portions of the lower
Hudson Valley into the Mid-Atlantic Day 4/Wednesday, as guidance
consensus continues to show a well-timed shortwave trough
overspreading this region. Medium-range guidance continues to show a
convective precipitation signal accompanying this impulse along with appreciable buoyancy and vertical wind shear. It should be noted
that convective overturning from Day 3 (Tuesday) storms may
stabilize part of this area, with the specific location of storms
becoming dependent on residual baroclinic boundaries. As such, the
exact placement of Wednesday's severe probabilities may need to be
adjusted accordingly.

Likewise, for Day 5/Thursday, another mid-level impulse will
traverse the northeast extent of the upper ridge and overspread the Mid-Atlantic. Given adequate buoyancy and shear likely remaining in
place, 15 percent severe probabilities have been introduced. As with
the previous day, these probabilities may need some adjustment in
future outlooks based on where airmass modification along baroclinic
zones occurs.

Medium-range guidance continues to show a pronounced mid-level
impulse, accompanied by adequate deep-layer shear and buoyancy,
impinging on the Mid-Atlantic on Day 6/Friday, which would support
at least an isolated severe threat. ML/AI guidance also suggests
that the Friday severe threat would encompass the ending stages of a
potential multi-day severe episode. Given the multiple preceding
days of storms and constant shift in favorable corridors modulated
by baroclinic zones, confidence is very low for realistically
pinpointing a focused severe area. However, it appears the Delmarva
may be the most likely area for seeing organized storm activity.

..Squitieri.. 08/30/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Mon Aug 31 08:48:32 2026

ACUS48 KWNS 310848
SWOD48
SPC AC 310846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Mon Aug 31 2026

Valid 031200Z - 081200Z

...DISCUSSION...
An upper ridge will persist across the TN Valley this week before
retrograding to the Plains states and further amplifying into early
next week. As this occurs, upper troughing will also amplify along
the East Coast and Interior West. The best chances for severe storms
will be closer to the East Coast Days 4-5 (Thursday-Friday) as a
series of mid-level impulses will crest the Ridge and traverse the
Mid Atlantic, where instability will be present.

...Days 4-6 (Thursday-Saturday) - Mid-Atlantic Region...
The amplification of the broader upper trough along the East Coast
will result in a farther southward shift of accompanying mid-level
impulses, which will promote deep-layer ascent over the Mid-Atlantic
region. The severe threat may also be modulated farther south given
established baroclinic zones from prior rounds of storms. On
Thursday, storms should develop along a differential heating zone
somewhere around Delmarva or points immediately west. Surface
dewpoints in the upper 60s to near 70 F beneath seasonably cool
temperatures aloft will yield 1500-3000 J/kg MLCAPE. Given over 30
kts of effective bulk shear expected, multicells, supercells, and
short bowing segments will likely develop, accompanied by a severe
wind/hail threat.

For Day 5 (Friday), the upper trough will amplify further, allowing
for a surface differential heating zone to become established across
the southern Mid-Atlantic, where adequate moisture and instability
will likely coincide with modest vertical wind shear, supporting
another day of severe potential. Damaging gusts will likely be the
main threat.

Some lingering severe potential may exist across the Carolinas on
Day 6/Saturday before the upper trough departs the region, as
indicated by some ML/AI guidance. However, predictability on the
timing of details (i.e. baroclinic boundaries and overlapping
corridors of vertical wind shear) is too low for the introduction of probabilities this outlook.

...Day 4 (Thursday) - Upper Midwest...
Some guidance depicts the potential for severe thunderstorms along
an effective warm front across portions of the Upper Midwest, where
rich low-level moisture will reside ahead of a surface trough. Given
stronger mid-level flow and cooler temperatures overspreading the
warm front, enough shear and instability may manifest to support a
severe threat. While calibrated guidance has been ramping up severe probabilities over this area, synoptic features (such as a
pronounced mid-level impulse) do not appear strongly evident in
deterministic guidance, precluding the addition of severe
probabilities to this outlook.

..Squitieri.. 08/31/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Tue Sep 1 09:59:18 2026

ACUS48 KWNS 010830
SWOD48
SPC AC 010828

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0328 AM CDT Tue Sep 01 2026

Valid 041200Z - 091200Z

...DISCUSSION...
An upper ridge will meander from the Mid-MS and TN Valleys toward
the Plains through the extended period, with upper troughs poised to
amplify along the East Coast and over the Interior West. Multiple
mid-level impulses will traverse this flow pattern, translating from
the Pacific Northwest to the northern Plains and Upper MS Valley,
then the Mid-Atlantic. It is in this elongated, roughly zonal
corridor that thunderstorm potential will be highest.

The severe threat with the relatively highest degree of
predictability will be across the Mid-Atlantic Days 4-5 (Friday and
Saturday). On Friday, a diffuse differential heating boundary,
generated by thunderstorm clusters from previous days, will likely
become established somewhere across the southern Mid-Atlantic. As an
upper trough amplifies over this differential heating boundary,
thunderstorms should develop amid rich low-level moisture beneath
stronger flow aloft. The more organized storms may produce damaging
wind gusts (hence the maintenance of 15 percent severe
probabilities). Calibrated ML/AI guidance suggests that the severe
threat may persist into Saturday across the Carolina Piedmont.
However, deterministic guidance shows the upper trough advancing
further into the Atlantic this weekend, along with upper support. As
such, storm coverage and initiation mechanisms for Saturday remain
too unclear this far in advance for the introduction of severe
probabilities at this time.

Amplification of the Interior West upper trough will support surface
lee troughing and accompanying low-level moisture advection across
the Plains states. While at least isolated severe thunderstorms may
occur any where from the northern/central High Plains toward the
Upper MS Valley, predictability of any severe potential is too low
this far out.

..Squitieri.. 09/01/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Wed Sep 2 08:46:20 2026

ACUS48 KWNS 020846
SWOD48
SPC AC 020844

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Wed Sep 02 2026

Valid 051200Z - 101200Z

...DISCUSSION...
Upper ridging will prevail over much of the central and eastern
CONUS into the middle of next week. The upper trough meandering over
the Interior West will eventually eject into the northern Plains and
pivot around the upper ridge while another upper trough (currently
along the East Coast) slowly drifts out to sea. As this occurs,
surface high pressure and cooler air will overspread the
northeastern quadrant of the U.S.

In the extended period, the best chance for some severe storms will
be in and around the Carolinas on Day 4/Saturday. A diffuse
differential heating zone will continue to drift south while being
reinforced from storms on previous days. By Saturday afternoon,
heating along this boundary, amid a very moist environment, will
promote damaging gust potential, hence the introduction of 15
percent severe probabilities.

There is also some hint at an MCS propagating southward across
eastern ND into northern and central MN along a moist and unstable
surface warm front on Saturday as well. While ML/AI calibrated
guidance consensus is beginning to elevate severe probabilities in
this area, upper support for this feature is quite weak at best,
limiting confidence for the introduction of severe probabilities
this outlook.

Lastly, the ejection of an upper trough into the northern Plains
early next week (i.e. next Monday or Tuesday) will support surface
lee troughing and the northward advection of rich low-level moisture
beneath cooler temperatures and stronger flow aloft. At least an
isolated severe thunderstorm risk may materialize from this
scenario, but details on timing and placement of key features are
too nebulous for the confident introduction of severe probabilities
this outlook.

..Squitieri.. 09/02/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Thu Sep 3 07:44:40 2026

ACUS48 KWNS 030740
SWOD48
SPC AC 030738

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0238 AM CDT Thu Sep 03 2026

Valid 061200Z - 111200Z

...DISCUSSION...
A mid-level trough will persist across the central CONUS through
early next week, before gradually weakening in favor of more
amplified, progressive upper troughs. Through the beginning of next
week, a few impulses ejecting into the northern Plains may be
accompanied by enough buoyancy and vertical wind shear to support an
isolated severe threat. However, confidence is too low to delineate
a more focused severe threat at this time. Likewise, there is a lack
of consensus among medium-range deterministic and ML/AI guidance
regarding the track and timing of any particular shortwave upper
trough later next week, precluding the introduction of any severe
probabilities this outlook.

..Squitieri.. 09/03/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Fri Sep 4 07:50:14 2026

ACUS48 KWNS 040750
SWOD48
SPC AC 040747

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0247 AM CDT Fri Sep 04 2026

Valid 071200Z - 121200Z

...DISCUSSION...
...Days 4-6/Mon-Wed -- Northern Plains to Great Lakes...

An upper shortwave trough is forecast to move across the Canadian
Prairies and Upper Midwest through Tuesday, before continuing east
toward the Lower Great Lakes on Wednesday. This will shift the
amplified upper ridge over the Plains at the beginning of the period
eastward over the Midwest, before flattening the ridge over the
Great Lakes through mid-week. As this occurs, enhanced
west/southwesterly flow will overspread portions of the northern
Plains/Upper Midwest and eventually the Great Lakes. A surface low
will track east/northeast across central Canada, and a trailing cold
front will move across the region on Tuesday/Wednesday. Some severe
potential could develop across the Dakotas into the Upper Midwest
Monday and Tuesday given enhance southwesterly flow aloft and
sufficient moisture ahead of the surface boundary. However, warm
midlevels may result in capping while large-scale ascent will be
focused mostly north of the international border. As a result,
severe potential and storm coverage are uncertain, precluding 15
percent probabilities at this time.

The cold front will weaken on Wednesday as the upper low lifts into
northern Ontario, and deep-layer flow will veer, becoming mostly
westerly. While some severe potential could develop into parts of
the Midwest and eastern Great Lakes vicinity, confidence is low
regarding where the greatest risk could emerge.

...Days 7-8/Thu-Fri...

The upper ridge is forecast to once again amplify over the Rockies
and into the Plains late in the week and severe potential appears
limited.

..Leitman.. 09/04/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sat Sep 5 07:55:52 2026

ACUS48 KWNS 050746
SWOD48
SPC AC 050744

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0244 AM CDT Sat Sep 05 2026

Valid 081200Z - 131200Z

...DISCUSSION...
...Days 4-6/Tue-Thu -- Central Plains to Great Lakes/Ohio Valley and Mid-Atlantic...

An upper shortwave trough will shift east across the Upper
Midwest/Great Lakes and northeast through Thursday. An associated
surface low will mainly remain over Canada, but a trailing cold
front will sweep across parts of the central Plains and Upper
Midwest on Tuesday, before continuing south and east into Kansas and
across the Great Lakes on Wednesday. By Thursday, the boundary is
expected to continue south and east across the Ohio Valley and
Mid-Atlantic. Stronger large-scale ascent will likely remain focused
near and north of the international border. Furthermore, the
corridor of deeper boundary layer moisture may be somewhat limited,
especially Tuesday into Wednesday, due to a prior cold frontal
passage and surface high pressure over the Midwest. Nevertheless,
enhanced deep-layer flow, and corridors of at least modest
instability along the cold front could support some severe risk.
However, confidence in 15 percent or greater coverage is low at this
time frame.

...Days 7-8/Fri-Sat -- Northern/Central Plains to Upper Midwest...

At the end of the period, another upper shortwave trough may dig
southeast from the Pacific Northwest and into the Plains. Another,
perhaps stronger, cold front could sweep across the Plains and the
Mid/Upper MS Valley. Depending on moisture return in the wake of the
earlier cold frontal passage, some severe risk could develop during
the weekend. Furthermore, large spread exists among various guidance
regarding the evolution of the this upper trough, resulting in
uncertainty in greater corridors of severe potential.

..Leitman.. 09/05/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sun Sep 6 07:51:36 2026

ACUS48 KWNS 060751
SWOD48
SPC AC 060749

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0249 AM CDT Sun Sep 06 2026

Valid 091200Z - 141200Z

...DISCUSSION...
An upper shortwave trough will move from the Great Lakes and over
the Northeast through Day 5/Thursday. As this occurs, a cold front
will develop southeast and east across much of the Midwest and
Northeast. Some strong to severe thunderstorm potential could
develop near the front, especially on Wednesday across parts of the
Midwest. However, deep-layer flow will largely remain parallel to
the boundary and stronger flow aloft will remain displaced to the
north of better instability.

Lower amplitude westerly upper-level flow is expected on Day
6/Friday before another upper trough digs southeast across the
western U.S. and emerges into the Plains by Day 8/Sunday. Some
severe potential could return to the Plains during the weekend as
low-level moisture returns across the region and lee cyclogenesis
occurs with the approach of the late-period upper trough. Trends
will be monitored and probabilities may become necessary across
parts of the central Plains vicinity if confidence in severe
potential increase.

..Leitman.. 09/06/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Mon Sep 7 07:34:00 2026

ACUS48 KWNS 070733
SWOD48
SPC AC 070732

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0232 AM CDT Mon Sep 07 2026

Valid 101200Z - 151200Z

...DISCUSSION...
An upper shortwave trough will weaken as it spread east across the
Northeast on Day 4/Thursday. As this occurs, a surface cold front
will shift east/southeast across the Northeast and the Mid-Atlantic.
A moist airmass will be in place, but vertical shear will weaken
through the day and deep-layer flow will remain parallel to the
surface boundary. Thunderstorms are expected in the vicinity of the
front, but may tend to be just to the cool side of the boundary.
Nevertheless, some low-end severe potential could develop from the
Ohio Valley to the Mid-Atlantic as the front sags southward across
the region.

During the weekend into early next week, forecast guidance suggests
a more progressive upper pattern will emerge across the northern
tier of the U.S. A series of shortwave upper troughs will move from
the northern Rockies to the Great Lakes and eventually the Northeast
during this time. Some severe risk is likely to develop ahead of the
upper shortwave troughs around the Day 5/Friday to Day 8/Monday time
period. However, large spread exists in both the timing and
intensity of these upper trough, resulting in vastly different
evolution and timing of key surface features (mainly surface low
position). These differences have large implications for where the
best corridors of severe potential will ultimately develop, but
severe probabilities may become necessary in later outlooks for
portions the northern/central Plains to the Upper Midwest during the
weekend.

..Leitman.. 09/07/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Tue Sep 8 07:26:44 2026

ACUS48 KWNS 080726
SWOD48
SPC AC 080724

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0224 AM CDT Tue Sep 08 2026

Valid 111200Z - 161200Z

...DISCUSSION...
...Days 4-5/Fri-Sat -- Plains to the Great Lakes vicinity...

Severe potential could develop across portions of the Plains into
the Upper Midwest on Day 4/Friday as boundary layer moisture spreads
northward ahead of a southeastward-advancing cold front. Moderate to
strong destabilization ahead of the front, and enhanced vertical
shear courtesy of a modest upper shortwave trough moving across the
northern Plains/Upper Midwest vicinity, should be sufficient for
organized convection mainly from Friday evening into early Saturday.

Some severe potential could persist into Day 5 Saturday as the
surface front stalls over the central/southern Plains vicinity but
continues eastward across the upper Great Lakes region. A moist
boundary layer will be in place, but stronger flow aloft will become
increasing displaced to the north of stronger instability,
precluding 15 percent delineation at this time.

...Days 6-8/Sun-Tue...

An upper trough over the northwestern U.S. will develop eastward
across the Plains and Great Lakes early next week. Another cold
front will move across the area, and some severe potential could
again sweep across the Plains to the Upper Midwest/Great Lakes
vicinity. Medium range forecast guidance generally maintains
stronger instability offset from enhanced flow aloft, partly due to
the early cold frontal passage in the Day 4-5/Friday-Saturday time
frame and strong surface high pressure over the Great Lakes in the
wake of that frontal passage. Trends will be monitored and
probabilities could become necessary in later outlooks.

..Leitman.. 09/08/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Wed Sep 9 07:29:22 2026

ACUS48 KWNS 090729
SWOD48
SPC AC 090727

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0227 AM CDT Wed Sep 09 2026

Valid 121200Z - 171200Z

...DISCUSSION...
...Day 4/Sat - Central Plains...

A cold front will stall across the central Plains on Saturday.
Low-level east/southeasterly flow will maintain rich boundary layer
moisture across KS and into eastern CO. Early day convection may be
ongoing in the vicinity of the stalled boundary within the low-level
warm advection regime. It is uncertain if airmass recovery and
renewed thunderstorm development will occur within the unstable warm
sector given nebulous large-scale ascent and modest vertical shear.
While low severe potential may eventually evolve, probability
appears less than 15 percent at this time.

...Days 5-6/Sun-Mon -- Central Plains to the Great Lakes...

An upper trough is forecast to move from the northern Rockies to the
Great Lakes through early Day 7/Tuesday. This will bring enhanced
southwesterly flow to portions of the northern/central Plains into
the Great Lakes, particularly on Monday. With the approach of the
trough, lee low development is forecast across the northern/central
High Plains on Sunday. Increasing southerly low-level flow will
transport moisture northward to NE/SD ahead of a
southeastward-advancing cold front. This could support some severe
risk across parts of the northern/central Plains and Mid-MO Valley
vicinity on Sunday. However, large spread exists among forecast
guidance with regards to the surface low placement, northward extent
of moisture return, and frontal position. As a result, corridors of
greater severe potential are uncertain on Sunday.

As the upper trough continues to lift east/northeast through the
Great Lakes on Monday, severe potential could develop eastward into
parts of the Mid/Upper MS Valley and upper Great Lakes vicinity.
Stronger deep-layer flow may become displaced to the north of better instability, and similarly large model spread continues into this
time frame. Depending on trends, severe probabilities could
eventually be needed for Sunday and/or Monday.

...Days 7-8/Tue-Wed...

Lower amplitude, quasi-zonal flow is expected to develop by the end
of the forecast period as the early-week uppers shortwave trough
lifts into eastern Canada and the sub-tropical high begins to
rebuild over the southern U.S. This should largely limit severe
potential, though abundant moisture will reside from the southern
Plains into the Southeast and Mid-Atlantic and daily sporadic strong
storms could still occur.

..Leitman.. 09/09/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Thu Sep 10 07:46:52 2026

ACUS48 KWNS 100746
SWOD48
SPC AC 100744

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0244 AM CDT Thu Sep 10 2026

Valid 131200Z - 181200Z

...DISCUSSION...
...Days 4-5/Sun-Mon -- Central Plains to the Mid-MS Valley...

A progressive upper pattern is expected early in the week. An
initial upper trough over the Great Lakes will spread east as upper
ridging builds across the Plains. Meanwhile, another upper trough
over the Northwest will shift east, moving across the northern
Plains and Upper Midwest on Monday, breaking down the upper ridge.
Surface high pressure over the Great Lakes on Sunday will suppress
low-level moisture southward across the central/southern Plains and
the Mid-MS/Lower OH Valleys. A very moist airmass will be in place
to the south of a stalled frontal boundary across the region.
Widespread showers and thunderstorms will be possible near the
surface boundary within low-level warm advection over the Middle to
Lower MO Valley. Vertical shear will be weak, but strong instability
could some strong gust potential, though convection may stay mainly
to the cool side of the surface boundary. Overall, severe potential
appears less than 15 percent on Sunday.

Severe potential will likely increase on Monday as the upper ridge
breaks down and stronger southwesterly flow overspread the
northern/central Plains to the Mid/Upper MS Valleys. Rich boundary
layer moisture will be in place ahead of a southeastward-advancing
cold front. Convection may be ongoing from the northern Plains into
IA/IL Monday morning. This results in some uncertainty in position
of best severe potential. Currently, the best overlap of rich
boundary layer moisture, strong instability and favorable shear near
the advancing cold front appears to be from eastern NE into IA and
vicinity. A 40+ kt southwesterly low-level jet is expected to
develop during the nighttime hours across KS/NE into IA, oriented
along the surface front, supporting an organized line of storms
tracking southeast ahead of the front, and promoting damaging wind
potential. Overall, the pattern appears favorable for at least
isolated severe storms on Monday, and a 15 percent delineation has
been included.

...Days 6-8/Tue-Thu...

The early week surface front will stall from the southern Plains to Mid-MS/Lower OH Valley through mid-week. A very moist airmass will
persist south of the boundary, and persistent low-level warm
advection could favor bouts of heavy rain. While some low-level
severe potential could develop where pockets of strong
destabilization occurs, weak vertical shear should largely limit
more widespread potential, precluding probabilities.

..Leitman.. 09/10/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Fri Sep 11 09:02:12 2026

ACUS48 KWNS 110901
SWOD48
SPC AC 110859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Fri Sep 11 2026

Valid 141200Z - 191200Z

...DISCUSSION...
Medium-range guidance indicates that a remnant cyclonic circulation
and associated mid-level troughing, likely accelerating across the
northern U.S. Rockies and adjacent international border vicinity by
early Monday, may be accompanied by substantive surface cyclogenesis
across southern Manitoba through northwestern Ontario Monday through
Monday night, before continuing east-northeastward into the higher
latitudes. It appears that this will occur coincident with the
transition to a more progressive regime across the northern
mid-latitude Pacific, including the gradual suppression of a
blocking high initially to the southeast of the Aleutians. It also
appears likely to coincide with the redevelopment of rather
prominent mid/upper ridging becoming centered across the Tennessee Valley/southern Appalachians vicinity, and increasingly influential
across much of the central and eastern U.S. into the middle to
latter portions of next week, before becoming suppressed and
retrograding west-southwestward.

In association with this regime, although there is some uncertainty
concerning low-level moisture return and destabilization, it still
appears that an evolving warm frontal zone could become a focus for
organized strong to severe thunderstorm development across parts of
the middle Missouri Valley toward Upper Midwest late Monday
afternoon into Monday night. Thereafter, the potential for
organized severe thunderstorm development appears generally low,
though there may still be areas of strong storm development with
rather isolated or marginal severe weather potential.

..Kerr.. 09/11/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sat Sep 12 08:43:44 2026

ACUS48 KWNS 120843
SWOD48
SPC AC 120841

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0341 AM CDT Sat Sep 12 2026

Valid 151200Z - 201200Z

...DISCUSSION...
In the wake of a vigorous short wave perturbation and associated
surface cyclone accelerating northeast of the upper Great Lakes into
the higher latitudes, a lingering near-surface frontal zone across
the lower Great Lakes and Ohio Valley into the central Great Plains
may provide a focus for occasional thunderstorm development into the
middle to latter portion of next week. However, this may largely
remain beneath the northern periphery of initially prominent
mid/upper ridging slowly beginning to retrograde from the Southeast
toward the Southwestern international border area. Forcing for
ascent and destabilization may not support more than rather isolated
and/or marginal severe thunderstorm potential, and even latest
available AI guidance generally suggests that this limited potential
will wane by late week into next weekend.

..Kerr.. 09/12/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sun Sep 13 08:22:50 2026

ACUS48 KWNS 130822
SWOD48
SPC AC 130820

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0320 AM CDT Sun Sep 13 2026

Valid 161200Z - 211200Z

...DISCUSSION...
Latest medium-range model output indicates that the initially
prominent Southeastern mid-level ridge will slowly retrograde west-southwestward and become increasingly suppressed across the
lower latitudes late this coming work week into next weekend.
However, it appears that the evolving westerlies across the U.S.
will remain modest to weak, with little potential for appreciable
surface cyclogenesis. While guidance suggests some continuing
potential for widely scattered strong thunderstorm development near
a lingering frontal zone across the Ohio into lower Missouri Valley
on Wednesday, it appears that this will diminish thereafter, with
generally negligible risk for organized severe thunderstorm
potential into and through next weekend.

..Kerr.. 09/13/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Mon Sep 14 08:56:30 2026

ACUS48 KWNS 140856
SWOD48
SPC AC 140854

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Mon Sep 14 2026

Valid 171200Z - 221200Z

...DISCUSSION...
Latest medium-range model output continues to indicate that
initially prominent Southeastern mid-level ridging will gradually
become suppressed late this week into next weekend. However, short
wave developments within the westerlies become more unclear by next
weekend into early next week. In general, it appears that a modest
to weak split flow will evolve across much of North America, as
larger positive mid-level height anomalies tend to develop across
interior Canada.

It is possible that diurnal destabilization will remain sufficient
to support areas of stronger daily thunderstorm development across
the U.S., supported by forcing for ascent associated with these
evolving perturbations. However, any associated severe weather
seems unlikely to become particularly well organized and probably
will remain rather isolated and/or marginal in nature.

..Kerr.. 09/14/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Tue Sep 15 08:44:30 2026

ACUS48 KWNS 150844
SWOD48
SPC AC 150842

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CDT Tue Sep 15 2026

Valid 181200Z - 231200Z

...DISCUSSION...
The latest medium-range model output still suggests that an
initially prominent mid-level ridge, across the central and southern
Great Plains through lower Ohio/Tennessee Valleys at the outset of
the period, will become suppressed late this week into next weekend.
But, this may be a bit slower to occur than previous guidance has
suggested, and the coinciding and subsequent pattern evolution
across much of North America has become more unclear due to model
spread. In general, though, it still appears that modest to weak
split westerlies will prevail, with little appreciable signal for
substantive surface cyclogenesis. Barring appreciable change, the
potential for organized severe thunderstorm development still
appears low through at least early next week.

..Kerr.. 09/15/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Wed Sep 16 08:58:38 2026

ACUS48 KWNS 160858
SWOD48
SPC AC 160856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Wed Sep 16 2026

Valid 191200Z - 241200Z

...DISCUSSION...
Latest medium-range model output suggests that modest pre-frontal
surface troughing across the Texas/Oklahoma Panhandle vicinity
through south central/eastern Kansas, and perhaps the slow moving
frontal zone across northeastern Kansas through northern
Missouri/southeastern Iowa, may provide focus for scattered strong
thunderstorm development late Saturday afternoon into evening. This
may be supported by forcing for ascent downstream of weak
larger-scale mid-level troughing slowly progressing across the
Rockies into Great Plains, with deep boundary-layer mixing along the
surface trough and higher boundary-layer moisture content along the
frontal zone contributing to thermodynamic profiles potentially
conducive to severe weather. However, with the belt of stronger lower/mid-tropospheric flow associated with a preceding impulse
tending to weaken and/or shift eastward near or to the south of the
Great Lakes region, it still appears that this potential will remain
relatively isolated in coverage and/or marginal in nature.

Thereafter, late this weekend through early next week, the spread
among model output concerning the mid/upper flow evolution
increases. However, even among the differing solutions, there is
little readily apparent that indicates an increase in organized
severe thunderstorm potential.

..Kerr.. 09/16/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Thu Sep 17 08:50:14 2026

ACUS48 KWNS 170850
SWOD48
SPC AC 170848

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0348 AM CDT Thu Sep 17 2026

Valid 201200Z - 251200Z

...DISCUSSION...
The latest ECENS and GEFS appear similar in their depiction of the
evolving mid/upper flow late this weekend through the middle of next
week. A weak mid-level trough and embedded low emerging from the
Intermountain West may weaken further while slowly progressing
across the central Great Plains through Ohio Valley, to the south of
a transient building mid-level high near the central Canadian/U.S.
border into the upper Great Lakes/northwestern Ontario vicinity.
Toward the middle to latter part of next week, remnant mid-level
troughing may tend to dig into and across the Mid Atlantic, as
mid-level ridging builds again across the Great Plains/Mississippi
Valley, downstream of a weak mid-level perturbation progressing into
the Southwest, and amplifying troughing within the stronger
westerlies offshore of the Pacific coast.

In association with this evolving regime, generally weak deep-layer
mean wind fields and increasingly limited potential for stronger destabilization are likely to minimize the risk for severe weather.

..Kerr.. 09/17/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Fri Sep 18 08:22:30 2026

ACUS48 KWNS 180822
SWOD48
SPC AC 180820

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0320 AM CDT Fri Sep 18 2026

Valid 211200Z - 261200Z

...DISCUSSION...
Initially zonal mid-level flow, with embedded low-amplitude impulses
traversing the central CONUS early next week, will give way to
gradual amplification of an upper ridge over the central U.S. The
best chance for any severe thunderstorms will be on Day 4/Monday
across the TN Valley, where a surface cold front, preceded by rich
low-level moisture, will be slow to clear the region. Thereafter,
drier low-level conditions will prevail across much of the central
and eastern CONUS, with surface high pressure poised to settle over
much of the U.S. between the MS River and the Appalachians, limiting
the severe threat.

..Squitieri.. 09/18/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sat Sep 19 08:26:34 2026

ACUS48 KWNS 190826
SWOD48
SPC AC 190824

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0324 AM CDT Sat Sep 19 2026

Valid 221200Z - 271200Z

...DISCUSSION...
An initially zonal mid-level flow regime will gradually transition
to a more amplified upper-air pattern, characterized by ridging over
the Plains states through the week into next weekend. As this
occurs, low-level moisture will continue to be shunted southward as
cooler mid-level temperatures remain relatively confined west of the
Rockies, and flow aloft remains modest at best. As a result, there
are no clear signals for an organized threat of severe thunderstorms
across the CONUS for Days 4-8 (Tuesday-Saturday).

..Squitieri.. 09/19/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sun Sep 20 08:25:00 2026

ACUS48 KWNS 200824
SWOD48
SPC AC 200823

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0323 AM CDT Sun Sep 20 2026

Valid 231200Z - 281200Z

...DISCUSSION...
Upper ridging will persist over the central U.S. through the
forecast period, with a meandering upper trough evolving into a
cut-off upper low off of the Mid-Atlantic Coast and an upper trough
amplifying over the Interior West late this week into next weekend.
Through the week, a relatively dry low-level airmass will settle
east of the MS River and west of the Rockies, limiting the severe
threat over the western and eastern third of the U.S. Some modest
moisture return is likely across the Plains given lee troughing.
However, upper support will be weak, which should limit the severe
threat across the central U.S. as well. As such, no organized severe
threats seem apparent for the CONUS Days 4-8 (Wednesday-Sunday).

..Squitieri.. 09/20/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Mon Sep 21 07:47:38 2026

ACUS48 KWNS 210747
SWOD48
SPC AC 210745

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0245 AM CDT Mon Sep 21 2026

Valid 241200Z - 291200Z

...DISCUSSION...
Upper ridging will persist over the central U.S. while a mid-level
cut-off low continues to meander just off of the Mid-Atlantic
coastline and multiple mid-level troughs traverse the Pacific
Northwest later this week into early next week. Through the Days 4-8
period, moisture return will be most prevalent over the Plains
states given surface lee troughing, and it is here where
thunderstorms will be most likely. However, the overall lack of
overlapping shear, buoyancy, and large-scale lift suggest that
organized severe potential is too low for the introduction of
probabilities this outlook.

..Squitieri.. 09/21/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Tue Sep 22 07:57:58 2026

ACUS48 KWNS 220757
SWOD48
SPC AC 220755

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 AM CDT Tue Sep 22 2026

Valid 251200Z - 301200Z

...DISCUSSION...
Upper ridging across the Plains and upper troughing over the western
and eastern U.S. will persevere through the weekend, before a more
progressive pattern takes shape and an upper trough ejects into the
Plains states early next week. Through the weekend, thunderstorm
chances should remain confined to the High Plains and points
westward, with little indication of an organized severe threat. By
early next week, there is some consensus among medium-range
deterministic guidance of a surface low developing over the central
Plains, encouraging low-level moisture advection beneath cooling
temperatures and increasing west-southwesterly flow aloft. However,
guidance does not show a favorable overlap of instability or
vertical wind shear, with AI/ML calibrated guidance also not
depicting a signal for severe, so probabilities have been withheld
this outlook.

..Squitieri.. 09/22/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Wed Sep 23 08:26:06 2026

ACUS48 KWNS 230825
SWOD48
SPC AC 230824

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0324 AM CDT Wed Sep 23 2026

Valid 261200Z - 011200Z

...DISCUSSION...
Upper ridging over the Plains will continue to break down this
weekend in favor of a more progressive upper-air pattern next
week.At least one pronounced mid-level trough will eject into the
Plains and Mid- to Upper-MS Valley in the Days 6-8/Monday-Wednesday period.Deterministic medium-range guidance consensus depicts surface
low development over the central and southern Plains in this
time-frame, encouraging seasonable low-level moisture return in the
process.

At the very least, moisture-driven buoyancy and subsequent scattered thunderstorm development should occur across the central and
southern Plains into the Mid- to Upper MS Valley next
Monday-Wednesday. However, vertical wind shear accompanying this
pattern is still expected to be weak. While a localized severe
threat may materialize at some point Monday-Wednesday, relevant
details are too unclear to pinpoint with probabilities at this
point, in agreement with the consensus of ML/AI calibrated guidance.

..Squitieri.. 09/23/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Thu Sep 24 08:28:42 2026

ACUS48 KWNS 240828
SWOD48
SPC AC 240826

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0326 AM CDT Thu Sep 24 2026

Valid 271200Z - 021200Z

...DISCUSSION...
A mid-level cutoff low will meander along the East Coast and will
gradually depart the region early next week as a mid-level trough
amplifies over the Rockies and impinges on the central U.S. Medium
range guidance consensus varies in the morphology of the upper
trough. The 00Z GFS features a rapidly progressing upper wave over
the Plains to the OH Valley Days 5-7 (Monday-Wednesday), while the
00Z Euro shows a mid-level trough evolving into a cut-off low that
meanders over the Plains through the week. Both scenarios result in
an appreciably strong surface low developing over the central Plains
sometime mid next week, accompanied by near 70 F surface dewpoints
and a buoyancy/vertical shear overlap supportive of a severe threat.
However, too much variability in guidance precludes the delineation
of severe probabilities this outlook.

..Squitieri.. 09/24/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Fri Sep 25 08:26:52 2026

ACUS48 KWNS 250826
SWOD48
SPC AC 250824

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0324 AM CDT Fri Sep 25 2026

Valid 281200Z - 031200Z

...DISCUSSION...
Upper troughing over the Interior West, containing multiple smaller
impulses, will gradually progress eastward to the Plains states
through the middle of the week (Days 5-7/Tuesday-Thursday) before
another mid-level trough approaches the central U.S. by next
weekend. Deterministic medium-range guidance consensus depicts the
development of a surface low over the southern Plains around Day
6/Wednesday, accompanied by seasonal low-level moisture return.
However, guidance also depicts a poor overlap of vertical wind shear
with the moist axis, likely inhibiting greater severe potential, in
agreement with calibrated ML/AI guidance consensus. As such, no
probabilities were introduced this outlook.

..Squitieri.. 09/25/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sat Sep 26 11:32:14 2026

ACUS48 KWNS 261131
SWOD48
SPC AC 261129

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0629 AM CDT Sat Sep 26 2026

Valid 291200Z - 041200Z

...DISCUSSION...
An upper trough is poised to gradually track eastward across the
Interior West and eject into the Plains states through next week.
Surface low development is likely across the southern Plains
sometime in the Days 5-6 (Wednesday-Thursday) time frame, when
low-level moisture advection and accompanying buoyancy will
appreciably increase. However, vertical wind shear is expected to be
limited, so organized severe potential does not appear evident,
though at least isolated severe is possible across the southern
Plains around next Thursday. Thereafter, a cold front will progress southeastward across much of the CONUS, displacing buoyancy across
much of the Plains and MS Valley, further limiting the severe
threat.

..Squitieri.. 09/26/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sun Sep 27 09:16:42 2026

ACUS48 KWNS 270916
SWOD48
SPC AC 270914

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0414 AM CDT Sun Sep 27 2026

Valid 301200Z - 051200Z

...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
During the mid-week, an upper-level low is forecast to move slowly
eastward from the southern Rockies into the southern Plains. As the
system approaches, low-level moisture will advect northward into the
southern and central Plains. A pocket of moderate instability may
develop over the southern High Plains by Wednesday afternoon. As
surface heating is maximized Wednesday afternoon, thunderstorms are
expected to form along and near the instability axis. A mid-level
jet, associated with the approaching system, is forecast to move
into the southern High Plains in the afternoon. This feature will
increase deep-layer shear. The timing of the mid-level jet is still
in question, but if the mid-level jet can move into the southern
Plains soon enough, then a severe threat could develop. Under this
scenario, isolated supercells with large hail and severe wind gusts
will be possible.

From Thursday into Friday, the upper-level trough is forecast to
remain over the southern High Plains. Ahead of the slow-moving
system, a moist and somewhat unstable airmass is forecast to be in
place both Thursday and Friday over parts of east-central Texas. On
these two days, deep-layer shear may be strong enough for an
isolated severe threat, mainly with storms that form near the
instability axis.

...Saturday/Day 7 and Sunday/Day 8...
Over the weekend, an upper-level trough is forecast to move across
the central U.S. Ahead of the trough, a moist and somewhat unstable
airmass is forecast to be in place over much of the Southeast, where
scattered to numerous thunderstorms will be possible each day. Of
the two days, the strongest instability is forecast to be on Sunday,
when an isolated severe threat will be possible. Uncertainty
regarding the spatial extent and magnitude is substantial at this
range.

..Broyles.. 09/27/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Mon Sep 28 08:58:16 2026

ACUS48 KWNS 280858
SWOD48
SPC AC 280856

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CDT Mon Sep 28 2026

Valid 011200Z - 061200Z

...DISCUSSION...
...Thursday/Day 4 to Friday/Day 5...
On Thursday, a mid-level trough is forecast to move through the
southern Plains. Ahead of the trough, an axis of moderate
instability is forecast to be in place Thursday afternoon from
central Texas north-northeastward into southwest Missouri.
Thunderstorm development is expected along and near parts of the
instability axis during the afternoon and evening. The area with the
greatest potential for severe storms appears to be across central
Texas, where current model forecast have moderate instability and
moderate deep-layer juxtaposed. However, the favored corridor is
forecast to be narrow, and there is some uncertainty concerning the
placement of the instability axis. Severe wind gusts and hail will
be possible with storms that form near the instability axis Thursday
afternoon and evening.

Thunderstorms will again be possible ahead of the trough on Friday,
from parts of the mid Mississippi Valley southwestward into the
Ark-La-Tex. Along this corridor, an isolated severe threat will be
possible with storms that develop near localized maximums of
instability. However, deep-layer shear is forecast to be relatively
weak, suggesting that any severe threat will remain marginal.

...Saturday/Day 6 and Monday/Day 8...
From Saturday to Monday, an upper-level trough is forecast to move
from the northern Plains into the Northeast. At the surface, a cold
front is forecast to advance southward from the Mid Mississippi and
lower Ohio Valleys to near the Gulf Coast. Scattered thunderstorms
will be possible each day ahead of the front, with the greatest
convective coverage in the Southeast. Deep-layer shear is expected
to remain relatively weak across the moist sector, which should
minimize the potential for severe storms.

..Broyles.. 09/28/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Tue Sep 29 08:47:56 2026

ACUS48 KWNS 290847
SWOD48
SPC AC 290845

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0345 AM CDT Tue Sep 29 2026

Valid 021200Z - 071200Z

...DISCUSSION...
Over the weekend, the pattern will consist of a large-scale trough
over the northeastern U.S.. Multiple shortwave troughs are forecast
to move eastward through the flow. A cold front appears likely to
move from the mid Mississippi and lower Ohio Valleys southward to
near the Gulf Coast. Isolated to scattered thunderstorms will be
possible each afternoon ahead of the front. Deep-layer shear is
expected to be too weak for a severe threat.

Early next week, mid-level flow is forecast to be west-northwesterly
over much of the nation. A relatively cool and dry airmass will be
in place over most of the continental U.S. The exception could be
along parts of the immediate Gulf Coast, where moisture and
instability may be sufficient for thunderstorm development. The
severe threat is expected to be minimal.

..Broyles.. 09/29/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Wed Sep 30 08:54:20 2026

ACUS48 KWNS 300853
SWOD48
SPC AC 300852

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Wed Sep 30 2026

Valid 031200Z - 081200Z

...DISCUSSION...
A mid-level cyclonic flow pattern will be in place over the weekend
across the northeastern U.S., as multiple shortwave troughs move
through the larger-scale trough. A cold front will advance southward
to near the Gulf Coast. Thunderstorm development will be possible
along and near the front during the day on Saturday and Sunday, but
no severe threat is expected.

During the upcoming early to mid week, mid-level flow is forecast to
become west-northwesterly across much of the U.S. A dry and
relatively cool airmass is forecast to be in place over the eastern
half of the nation. On the western edge of the high pressure area,
low-level moisture advection will be possible across the Great
Plains. Thunderstorm development may occur on Tuesday and Wednesday
in parts of the central Plains, as a cold front approaches. Although instability and deep-layer shear are not forecast to be sufficient
for a substantial severe threat, a few marginally severe storms will
be possible in areas that destabilize the most.

..Broyles.. 09/30/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Thu Oct 1 09:02:58 2026

ACUS48 KWNS 010902
SWOD48
SPC AC 010900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Thu Oct 01 2026

Valid 041200Z - 091200Z

...DISCUSSION...
Early next week, a large-scale upper-level trough will move from the
Great Lakes region into the western Atlantic, as mid-level flow
become west-northwesterly over much of the nation. At the surface, a
large surface high will be dominant on Sunday and Monday from the
Mississippi Valley to the East Coast.

Further west into the Great Plains, a cold front is forecast to
advance southeastward through the Dakotas on Tuesday. Ahead of the
front, moisture advection is expected over the Great Plains. By
Tuesday afternoon, an axis of instability should be in place from
western Kansas into north-central Nebraska. Along and near the
instability axis, an isolated severe threat will be possible from
late afternoon into the evening. On Wednesday, the axis of
instability is forecast to shift southeastward into the mid Missouri
Valley. An isolated severe threat will again be possible near and
ahead of the front from late afternoon into the evening.

By Thursday, model forecasts move an upper-level trough into the
Great Lakes, as a subtle shortwave ridge moves through the central
U.S. A relatively dry and cool airmass over much of the U.S. is
expected to make thunderstorm development unlikely in most areas.

..Broyles.. 10/01/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Fri Oct 2 08:18:50 2026

ACUS48 KWNS 020818
SWOD48
SPC AC 020817

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0317 AM CDT Fri Oct 02 2026

Valid 051200Z - 101200Z

...DISCUSSION...
Severe storm potential from Monday/D4 to Friday/D8 is forecast to be
minimal.

A deep upper trough will move across eastern Canada and the
northeastern USA Mon/D4 into Tue/D5, with a cold front already
offshore and high pressure building in from the west. Behind the
ejecting upper trough, moderate northwest flow aloft will persist
across the northern tier of states, with some trough amplification
possible over the Great Lakes Wed/D6 into Fri/D8. That said, a
minimally unstable air mass will exist over most of the CONUS, with
little severe thunderstorm potential. A few stronger storms cannot
be ruled out around Thu/D7 over the upper Midwest beneath the
northwest flow regime, but this low-predictability scenario will
depend heavily on enough moisture returning to the region. As such,
no areas are currently forecast.

..Jewell.. 10/02/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sat Oct 3 07:43:02 2026

ACUS48 KWNS 030742
SWOD48
SPC AC 030740

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0240 AM CDT Sat Oct 03 2026

Valid 061200Z - 111200Z

...DISCUSSION...
Severe weather potential is forecast to be low across the CONUS
through the period.

Northwest flow aloft is forecast to persist from the northern
Rockies & Plains eastward into the northeastern states. Periodic
embedded waves and associated frontal intrusions will maintain a
relatively stable air mass across the same areas, while the more
substantial low-level moisture and instability remain largely over
the Gulf of America and western Atlantic Ocean.

Some low-end thunderstorm potential will be possible late Thur/D6
into Fri/D7 over the Upper Midwest, with primarily late day/evening
elevated thunderstorms possible as the large-scale trough over
eastern Canada starts to lift, and low-level warm advection occurs
over the northern Plains.

..Jewell.. 10/03/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Sun Oct 4 09:02:08 2026

ACUS48 KWNS 040901
SWOD48
SPC AC 040900

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Sun Oct 04 2026

Valid 071200Z - 121200Z

...DISCUSSION...
For Wed/D4 through about Fri/D6, severe chances will be minimal
across the CONUS as a broad upper trough affects the Great Lakes
into the Northeast, with high pressure keeping the higher dewpoints
primarily offshore over the Gulf of America.

For late Fri/D6 into Sun/D8, predictability becomes low as models
indicate a possible tropical cyclone over parts of the southwestern
Gulf of America (NHC 30% change of cyclone formation). This, along
with a possible weak shortwave trough developing over TX/northern
Gulf Coast, could result in a rapid northward surge of tropical
moisture and enhanced shear. This area will be monitored in upcoming
outlooks as the situation evolves.

..Jewell.. 10/04/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Mon Oct 5 08:59:16 2026

ACUS48 KWNS 050859
SWOD48
SPC AC 050857

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Mon Oct 05 2026

Valid 081200Z - 131200Z

...DISCUSSION...
Little severe weather threat is evident from Thur/D4 through Fri/D5,
as a broad upper trough over the Great Lakes and Northeast maintain
cool conditions, with high pressure over much of the eastern states
preventing moisture return.

For late Sat/D6 into Sun/D7, conditional severe potential may
develop along the northern Gulf Coast, depending on the evolution of
a tropical disturbance currently over the southwest Gulf of America.
NHC currently denotes a 50% chance of cyclone development. A weak
midlevel trough is also forecast to develop over TX, and move across
the Gulf Coast states during the same time. The combination of
increasing moisture and shear could result in an area of tornado
potential. Any such event is highly conditional on cyclone
formation, and potential will continue to be monitored.

From Sun/D7 and beyond, models suggest a western trough may develop,
though model spread is high.

..Jewell.. 10/05/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Tue Oct 6 08:14:24 2026

ACUS48 KWNS 060814
SWOD48
SPC AC 060812

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0312 AM CDT Tue Oct 06 2026

Valid 091200Z - 141200Z

...DISCUSSION...
A surface high will move from the OH Valley into the Northeast on
Fri/D4 as an upper trough lifts out of the region and temporary
upper ridging occurs. A stationary boundary is still forecast to be
along the northern Gulf Coast at this time, and a weak midlevel wave
will begin to form over TX. Meanwhile, a potential tropical cyclone
may develop toward the central Gulf of America.

Low-level winds will begin to veer to a southeasterly direction
along the Gulf Coast late Fri/D4 into Sat/D5, as the potential
tropical cyclone evolves. NHC currently gives a high probability of
this occurring. As such, an influx of rich moisture will develop out
of the south, with a substantial rain shield and embedded
thunderstorms likely along the northern Gulf Coast beginning Fri/D4
night. Initially, surface temperatures over land will remain cool
due to precipitation and initial modification of the surface ridge
air mass.

At this time, it appears Sat/D5 is the most likely time for the more substantial low-level warming to occur, with tropical yet
sufficiently unstable profiles. Of particular note is how the
developing shortwave trough over TX interacts with the tropical low.
Some models indicate 40-45 kt midlevel winds, which would complement
the strong low-level shear and favor low-topped supercells with
tornado potential. The greatest threat area should be along the
coastal counties given expected poor low-level lapse rates farther
inland. Initial elevated convection may give way to an east-west
zone of supercells as the coastal baroclinic zone moves inland. Some
additional threat into Sun/D6 may exist as well.

For the period Mon/D7 into Tue/D8, models are now developing an
amplified upper trough over the western CONUS. Low-level moistening
will be most prominent later in the period, and could eventually
result in a zone of strong to severe storm potential, however,
predictability is quite low at this time.

..Jewell.. 10/06/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Tue Oct 6 08:31:54 2026

ACUS48 KWNS 060831
SWOD48
SPC AC 060829

Day 4-8 Convective Outlook RESENT 1
NWS Storm Prediction Center Norman OK
0329 AM CDT Tue Oct 06 2026

Valid 091200Z - 141200Z

...DISCUSSION...
A surface high will move from the OH Valley into the Northeast on
Fri/D4 as an upper trough lifts out of the region and temporary
upper ridging occurs. A stationary boundary is still forecast to be
along the northern Gulf Coast at this time, and a weak midlevel wave
will begin to form over TX. Meanwhile, a potential tropical cyclone
may develop toward the central Gulf of America.

Low-level winds will begin to veer to a southeasterly direction
along the Gulf Coast late Fri/D4 into Sat/D5, as the potential
tropical cyclone evolves. NHC currently gives a high probability of
this occurring. As such, an influx of rich moisture will develop out
of the south, with a substantial rain shield and embedded
thunderstorms likely along the northern Gulf Coast beginning Fri/D4
night. Initially, surface temperatures over land will remain cool
due to precipitation and initial modification of the surface ridge
air mass.

At this time, it appears Sat/D5 is the most likely time for the more substantial low-level warming to occur, with tropical yet
sufficiently unstable profiles. Of particular note is how the
developing shortwave trough over TX interacts with the tropical low.
Some models indicate 40-45 kt midlevel winds, which would complement
the strong low-level shear and favor low-topped supercells with
tornado potential. The greatest threat area should be along the
coastal counties given expected poor low-level lapse rates farther
inland. Initial elevated convection may give way to an east-west
zone of supercells as the coastal baroclinic zone moves inland. Some
additional threat into Sun/D6 may exist as well.

For the period Mon/D7 into Tue/D8, models are now developing an
amplified upper trough over the western CONUS. Low-level moistening
will be most prominent later in the period, and could eventually
result in a zone of strong to severe storm potential, however,
predictability is quite low at this time.

..Jewell.. 10/06/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Wed Oct 7 08:28:04 2026

ACUS48 KWNS 070827
SWOD48
SPC AC 070826

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0326 AM CDT Wed Oct 07 2026

Valid 101200Z - 151200Z

...DISCUSSION...
For Sat/D4, the latest NHC guidance (as of this writing) has brought
the center track of the developing hurricane farther east toward
southern AL and the western FL Panhandle, and thus the Slight Risk
for tornado potential has been shunted east. Further, given the
likelihood of a stronger cyclone and faster forward motion, the
Slight Risk has also been expanded farther north/inland, as it
appears the mid 70s F dewpoints may expand across much of southern
AL. The strong low-level shear east of the center, and increasing
midlevel winds (as a shortwave trough deepens over the Lower MS
Valley) should support a few supercells with tornado potential. It
should be noted that the Slight Risk area may shift in subsequent
outlooks if the center track shifts.

For Sun/D5, the shortwave trough and remnants of the tropical
cyclone will generally move northeastward toward the Appalachians
and toward the Carolinas and southern Mid Atlantic. It is possible
that the upper system outruns the unstable warm sector, but at least
a low end chance of severe is not out of the question.

For the remainder of the period, there may be a chance of severe
storms over parts of the Southern Plains into Wed/D8 as a developing
western trough eventually moves across the Rockies, and low-level
moisture returns in earnest. However, the evolution of this trough
and date of wave ejection is low predictability.

..Jewell.. 10/07/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Thu Oct 8 08:23:36 2026

ACUS48 KWNS 080823
SWOD48
SPC AC 080821

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0321 AM CDT Thu Oct 08 2026

Valid 111200Z - 161200Z

...DISCUSSION...
On Sun/D4, a shortwave trough and surface low (previously associated
with the tropical cyclone) will move east across the TN/OH Valleys,
and toward the Mid Atlantic Sunday night. A warm front and northward
surge of moisture will occur from GA/Carolinas into VA/DelMarVa,
resulting in at least a few hundred J/kg MLCAPE. Substantial rain
and thunderstorms are likely to exist over the region, and therefore
boundary layer warming/destabilization is in question. Most models
show little if any daytime heating. As such, predictability is low
at this time, but at least low severe probabilities could be added
in later outlooks as the scenario evolves.

To the west, a shortwave trough with tropical remnants will affect
southern CA and AZ, with strong southwest winds aloft. Substantial
model differences exist regarding destabilization due to increasing
clouds and rain, though some severe wind and even hail potential
cannot be ruled out where instability is locally higher. This area
too may see at least low severe probabilities in later outlooks as predictability increases.

For the remainder of the period through Thu/D8, a potential western
trough ejection may occur into the Plains, with the strongest
instability on or after Wed/D7 as moisture return becomes more
established with upper 60s F dewpoints possible from TX into OK and
KS. As such, this area will also be monitored as the event nears,
and as trough timing becomes more predictable.

..Jewell.. 10/08/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

From COD Weather Processor @1:2320/107 to All on Fri Oct 9 18:40:14 2026

ACUS48 KWNS 090905
SWOD48
SPC AC 090903

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0403 AM CDT Fri Oct 09 2026

Valid 121200Z - 171200Z

...DISCUSSION...
There is reasonably good agreement in 00Z deterministic and ensemble
guidance that a mid/upper-level low centered over the Sierra Nevada
or Great Basin on Day 4/Monday will evolve into an open wave while
progressing into the Great Plains on Day 6/Wednesday. Thereafter,
model spread increases in the evolution of the large-scale pattern.

...Day 4/Monday...

Some severe weather threat could materialize during the afternoon
along a surface boundary over the Upper Midwest where at least
modest instability will coincide with sufficiently strong deep-layer
shear to support organized storm modes. However, low-amplitude
ridging downstream from the western U.S. trough along with
uncertainty in the extent of air mass destabilization renders the
threat too questionable to include a 15% area.

...Day 5/Tuesday...

Increasing height falls and midlevel flow will overspread the
central and southern High Plains, which in turn will induce a
deepening lee cyclone, likely over southeast CO. At the surface, a
front is expected to stretch from the low through the OH Valley into
the Mid-Atlantic with a dryline trailing south from the cyclone into
eastern NM or western TX. Isolated strong to severe storms appear
possible along the length of the front from the Mid-Atlantic into
the central and southern Plains. Organized severe storm potential
appears most probable over the central and southern High Plains
Tuesday afternoon into evening in the vicinity of the lee cyclone
and strengthening low-level jet, where the strongest forcing for
ascent and vertical shear will coincide.

...Day 6/Wednesday...

As mentioned above, there is overall model agreement that a
short-wave trough and a strengthening deep-layer wind field will
advance into the Great Plains at this time. However, there are
slight timing and latitudinal differences in the track of the
midlevel system and the associated surface low. Despite these
differences, it does appear that a broad, moist, and unstable warm
sector will exist. As such, organized severe storms appear possible
with the highest confidence in occurrence over portions of eastern
KS into MO where guidance currently indicates the most favorable
overlap of instability and vertical shear. The currently delineated
area may move slightly and/or expand in the coming days as forecast
confidence increases.

...Days 7 and 8/Thursday and Friday...

Some severe weather threat could develop over the Great Lakes and OH
Valley on Thursday in association with the mid-level trough
discussed in the previous sections. However, confidence in organized
severe storm potential is currently too low given the model
variability in the specific details of the trough and associated
frontal system.

..Mead.. 10/09/2026

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* Origin: capitolcityonline.net * KY, USA (1:2320/107)

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