SPC - No watches are valid as of Fri Sep 4 17:07:02 UTC 2026

No watches are valid as of Fri Sep  4 17:07:02 UTC 2026.

SPC - No MDs are in effect as of Fri Sep 4 17:07:02 UTC 2026

No Mesoscale Discussions are in effect as of Fri Sep  4 17:07:02 UTC 2026.

SPC Sep 4, 2026 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook
      
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0755 AM CDT Fri Sep 04 2026

Valid 041300Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
GREAT LAKES INTO THE MID-ATLANTIC STATES...

...SUMMARY...
A couple of organized clusters of thunderstorms may develop across
the southern Great Lakes and mid/upper Ohio Valley today through
tonight, accompanied by the risk for damaging wind gusts.  More
widely scattered strong thunderstorms east of the Blue Ridge may
also pose potential for damaging wind gusts this afternoon and
evening.

...Southern Great Lakes into Mid Atlantic...
Early-morning satellite imagery shows a deep cyclone over the
Pacific Northwest and upper ridging covering the majority of the
CONUS east of the Rockies. A belt of enhanced mid-level flow
persists between these two features, arcing anticyclonically from
southern CA through the central Rockies and northern Plains into the
Upper Midwest/Upper Great Lakes and eventually through the
Northeast. Recent surface analysis shows a reservoir of low-level
moisture beneath the upper ridging, to the south and east of this
belt of stronger mid-level flow. Much of this area is void of
notable surface features, but a weak front does extend from southern
New England through southern NY, central Lower MI, and central WI to
a weak low over southern MN. A large cluster of showers and
thunderstorms to the south of this front from southern WI into
southern Lower MI. This cluster, which was initiated by warm-air
advection across MN and WI is forecast to continue southeastward
today, likely encountering a diurnally destabilized airmass.

The steeper mid-level lapse rates will remain displaced west of this
region, but ample low-level moisture (i.e. upper 60s/low 70s
dewpoints) coupled with afternoon temperatures from the mid 80s to
mid 90s will still support moderate to strong buoyancy. As such,
reintensification and/or new development is anticipated as the
ongoing cluster continues southeastward. Much of this region will be
on the southern fringe of the stronger deep-layer shear, with bowing
line segments as the predominant storm mode. The best overlap
between buoyancy and shear is expected across central and eastern
OH, where a corridor of greater potential for damaging gusts exists.


The threat for damaging gusts will extend into the Mid-Atlantic this
afternoon and evening amid a very warm and moist airmass. Vertical
shear will be weak, but ample moisture (i.e. PW values from 1.8" to
2"), strong buoyancy, and steep low-level lapse rates will support
the potential for strong outflow capable of wind damage. Bowing line
segments will be the primary storm mode here as well.

...Central Plains...
Weak lee troughing could contribute to modest low-level convergence 
from western KS across western/central NE into southwest SD.
Dewpoints will likely be in the low to mid 60s within this
convergence zone, and steep mid-level lapse rates will contribute to
moderate/strong buoyancy. Even so, warm mid-levels may prevent the
airmass from completely destabilizing. The remaining convective
inhibition, coupled with the presence of large-scale height rises
across the region, casts doubt to whether successful convective
initiation will occur. Any mature updrafts could result in strong
downdraft, but uncertainty is too high to introduce any
probabilities with this outlook.

..Mosier/Lyons.. 09/04/2026


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SPC Sep 4, 2026 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook
      
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1146 AM CDT Fri Sep 04 2026

Valid 041630Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
GREAT LAKES INTO THE MID-ATLANTIC STATES...

...SUMMARY...
A couple of organized thunderstorm clusters are expected to develop
across the southern Great Lakes and mid/upper Ohio Valley today
through tonight, accompanied by the risk for damaging wind gusts.
More widely scattered strong thunderstorms east of the Blue Ridge
may also produce damaging wind gusts this afternoon and evening.

...Midwest/southern Great Lakes to Mid-Atlantic States...
As large-scale pattern amplification occurs, a belt of moderately
strong northwesterly flow aloft will tend to overlie a frontal zone
that extends from southern portions of Minnesota/Wisconsin
east-southeastward to Pennsylvania/New Jersey. That said, ongoing
convection has effectively modified/southward-shunted the effective
front in several areas, and this will be the primary focus for storm
intensification/redevelopment this afternoon, as well into the
evening/late night.

The steeper mid-level lapse rates will remain displaced west of the
region, but ample low-level moisture (i.e. upper 60s/low 70s
dewpoints) coupled with afternoon temperatures from the mid 80s to
mid 90s will still support moderate to strong buoyancy near/south of
the effective boundary. General storm re-intensification and/or new
development is anticipated this afternoon, particularly south/ahead
of currently ongoing clusters. Bowing line segments will be the
predominant storm mode, with damaging winds as the most common
hazard. 

The threat for damaging wind gusts will extend southeastward into
the Mid-Atlantic this afternoon and evening amid a very warm and
moist airmass. Vertical shear will be weaker with southward extent,
but ample moisture (i.e. PW values from 1.8" to 2"), strong
buoyancy, and steep low-level lapse rates will support the potential
for strong outflow capable of wind damage. Bowing line
segments will be the primary storm mode here as well.

...Southern Wisconsin/southern Lake Michigan vicinity...
The same general meteorological thematic scenario as described in
the prior section applies to this region, and severe probabilities
have been extended westward regionally, albeit for a somewhat
conditional/uncertain scenario. A robust reservoir of
moisture/locally extreme buoyancy will exist particularly to the
south of ongoing midday convection. The region will be influenced by
the amplifying upper ridge, but there is at least some possibility
that storm redevelopment/intensification could occur near/east of
the surface triple point and/or near outflow, with some related
severe potential. Development could also occur toward the southern
Lake Michigan vicinity later tonight as isentropic ascent increases
near/northeast of the surface boundary.

...North-central Plains/Dakotas...
While perceived severe probabilities remain below 5%, some
strong/sporadic severe potential may exist also South Dakota, far
northern Nebraska and/or southeast North Dakota later today through
late tonight, although confidence in specific meteorological
scenarios remains low.

Weak lee troughing will contribute to modest low-level convergence
from western Kansas across western/central Nebraska into southwest
South Dakota. Dewpoints will likely be in the low to mid 60s F
within this convergence zone, and steep mid-level lapse rates will
contribute to moderate/strong buoyancy. Even so, warm mid-levels may
prevent the airmass from completely destabilizing. The remaining
convective inhibition, coupled with the presence of large-scale
height rises across the region, casts doubt to whether successful
convective initiation will occur. Any mature updrafts could result
in strong downdraft, but uncertainty remains high. Other storm
development could occur tonight, potentially as a byproduct of a
subtle mid-level wave/ongoing convection ongoing across South Dakota
this morning.

..Guyer/Thornton.. 09/04/2026


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SPC Sep 4, 2026 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook
      
Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1203 PM CDT Fri Sep 04 2026

Valid 051200Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE OHIO
VALLEY AND APPALACHIANS TO THE CAROLINAS...

...SUMMARY...
Severe thunderstorms capable of damaging gusts are possible across
portions of the central Appalachians and Carolinas on Saturday
afternoon and evening. Isolated occurrences of large hail and severe
wind gusts also appear possible over parts of the northern Plains
and vicinity Saturday afternoon into night.

...Eastern Carolinas...
A mid-level trough across the western Atlantic is forecast to
retrograde slightly on Saturday with an associated surface front
expected to move slowly southward from the Mid-Atlantic to the
Carolinas. South of this cold front, a very moist airmass will be in
place with strong instability, particularly across the eastern
Carolinas. Farther west, downslope flow off the mountains may result
in a more stable environment in the western half of the Carolinas.
This signal varies within the guidance, and confidence is not high
enough to lower probabilities across this area, but the greater
threat should remain farther east where mid to upper 70s dewpoints
and around 30 knots of shear amid a front and height falls aloft
should support scattered strong to severe storms capable of mostly
damaging winds.

...Ohio Valley...
Strong heating across eastern Kentucky and vicinity should provide
an unstable and uncapped airmass by Saturday afternoon. Mid-level
flow will be relatively weak across this region (~20 knots) and
therefore, effective shear and storm organization is expected to be
weak. However, strong heating and steep lapse rates will support
some damaging wind threat Saturday afternoon/evening. Some guidance
shows these storms clustering and traversing the Appalachians and
continuing into western Virginia and western North Carolina. The
relatively weak shear, and potential for lesser instability due to
downslope flow across the eastern Appalachians casts significant
doubt on this potential. 

...Central to northern Plains...
Most guidance shows ongoing thunderstorms within a warm-air
advection zone across southeast South Dakota Saturday morning.
Isolated large hail is possible with this activity during the
morning hours before the low-level jet weakens and backs and these
thunderstorms weaken by late morning.

As the mid-level ridge strengthens during the day Saturday, height
rises will be present across much of the Plains. Despite this,
upslope flow will develop across the central High Plains. Within
this region, forecast soundings show moderate instability but weak
mid-level flow. This will support some isolated large hail and
severe wind gusts, but the lack of shear should limit the overall
severe weather threat.

A more organized cluster of storms may develop across southwest
Nebraska, but do not expect storm intensity to warrant higher severe
weather probabilities. 

After 00Z, the low-level jet is forecast to strengthen across the
central/northern Plains. This could result in some isolated storm
development during the overnight period into the Dakotas. Given the
strong instability forecast across this region, these storms could
contain large hail or damaging wind gusts.  

...North-central Montana...
A mid-level jet streak on the eastern periphery of a mid-level
trough across the Northwest will remain across Montana for much of
the period on Saturday. Weak instability may develop as temperatures
warm into the 70s across west-central Montana Saturday afternoon.
Overall, moisture will be lacking (30s F dewpoints) which should
limit the severe weather threat. However, there is some instability
within a zone of moderate to strong shear. Therefore, one or two
fast-moving strong storms may develop within this zone, but the
overall lack of moisture/instability precludes severe weather
probabilities at this time.

..Bentley.. 09/04/2026


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SPC Day 1 Fire Weather Outlook

SPC Day 1 Fire Weather Outlook
          
Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1149 AM CDT Fri Sep 04 2026

Valid 041700Z - 051200Z

No changes have been made to the ongoing forecast. Elevated to
locally critical fire weather conditions are expected today across
portions of the northern Plains where fuels remain receptive. Poor
overnight RH recoveries were observed in much of central-northern
Wyoming, while modest to good recoveries occurred in the western
Dakotas and eastern Montana. 16z satellite imagery depicts
dissipating fog over western North Dakota and clear skies beyond the
Powder River Basin, allowing RH values to decline as daytime heating
ensues. High temperatures of 90-100 F and south-southwesterly
sustained winds of 15-20 mph amid 10-15% RH will maintain an
Elevated fire weather threat across the region this afternoon.
Please see the previous discussion for more information.

..Elizalde-Garcia.. 09/04/2026

.PREV DISCUSSION... /ISSUED 1255 AM CDT Fri Sep 04 2026/

...Synopsis...
An upper-level trough will remain in place over the Pacific
Northwest today, with upper-level ridging located across the
southern Great Plains. This will support the persistence of modest
southwesterly, mid-level flow across the northern Rockies and
northern High Plains while a surface low migrates slowly eastward
across central Montana. This will promote another day of Elevated
fire weather conditions across portions of the northern High Plains
today.

...Portions of the Northern Rockies and northern High Plains...
Elevated surface winds of 5-10 mph in conjunction with a modest
strengthening of southeasterly 850 mb flow owing to a deepening
surface low over western/central Montana will generally limit
overnight humidity recoveries into this morning, with RH of 15-30%
noted across the outlook area as of 0500 UTC. A very dry boundary
layer will persist across the region today, with minimum RH values
of 10-15% likely this afternoon across south-central/southeastern
Montana, central Wyoming, and adjacent areas of the northern Great
Plains. South-southwesterly surface winds of 15-20 mph aligned with
low RH and receptive fuels will promote elevated fire weather
concerns across this area today.

The Elevated highlights were expanded slightly across portions of
central Montana with this outlook based on the latest guidance and
HREF wind/RH probabilities. Brief periods of locally critical
conditions may be possible in the lee of the Big Horn Mountains
where the latest guidance depicts the greatest potential for
stronger sustained surface winds. However, confidence in a sustained
period of 20+ mph winds is low at this time.

...Great Basin...
Similarly dry, southwesterly flow is forecast today across the
southeastern portions of the Great Basin. While localized elevated
fire weather conditions may impact locations where recent rainfall
was minimal and/or where pockets of dry fuels remain, generally
marginal fuels across southeastern NV and southwestern UT should
mitigate a broader fire weather threat.

...Please see www.spc.noaa.gov/fire for graphic product...


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