Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0103 AM CDT Tue Sep 01 2026

Valid 011200Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL/NORTHERN PLAINS AND MIDWEST INTO PARTS OF PENNSYLVANIA
NEW YORK AND NEW JERSEY....

...SUMMARY...
Scattered strong to severe storms are possible over the central
Plains and Midwest, as well as parts of New York, Pennsylvania and
New Jersey.

...Eastern Great Lakes, OH valley and NY/NJ...
Scattered showers and thunderstorms are expected to be ongoing early
in the period across parts of NY associated with a lead shortwave
trough and warm advection. Remnant clouds, showers and storms should
persist trough the day along a northwest to southeast warm front
across northern/eastern NY into NJ. A second shortwave trough and
mid-level jet will approach during the afternoon providing ascent
across the upper OH Valley and NY. 

Despite modest mid-level lapse rates, 70s F surface dewpoints and
strong heating will support a very unstable air mass with MLCAPE of
3000+ J/kg south of the warm front. Increasing vertical shear ahead
of the mid-level speed max will favor a mix of supercells and line
segments across southern NY, PA and NJ through the afternoon.
Scattered damaging gusts and isolated hail are the most likely
hazards. Low-level shear will be greatest near the southern Hudson
Valley and the instability gradient into northeast PA/northern NJ.
Enhanced ESRH could support a couple of tornadoes with the stronger
supercells or QLCS segments.

Some guidance shows additional thunderstorms developing over
southern lower MI and ON early Wed, associated with another
mid-level wave speed max across the eastern Great Lakes. Sufficient
elevated buoyancy (2000 J/kg MUCAPE) and vertical shear will exist
for some damaging wind threat should this occur. This scenario
remains uncertain, but these storms could potentially track
southeast and organize, approaching northeast OH and western NY/PA
by 12z Wed morning.

...Central/northern Plains...
A stalled front will lift northward across parts of NE/SD as several
low-amplitude shortwave troughs move out of the Rockies and onto the
Plains. Weak ascent from these features will modestly deepen a
surface low across NE and SD. In response, strengthening southerly
flow/moisture should result in moderate to strong destabilization by
early afternoon.

Convection lingering from overnight may begin to rejuvenate along
and north of the front across SD as heating increases through the
afternoon. Meanwhile, inhibition owing to warm mid-level
temperatures will likely remain in place most of the day south of
the front. Weak ascent and strong heating should be sufficient to
support isolated storm development by late afternoon. A belt of
enhanced southwesterly flow aloft would favor organization with
supercell or strong clusters likely. Hail (some 2+ inch) is possible
along with damaging gusts given a supercell mode. A tornado or two
is also possible given the potential for supercells to reside along
the boundary where low-level flow will be substantially backed and
hodographs expanded.

Eventually, one or more clusters may merge into an MCS and track
eastward along the front into eastern SD and southern MN through the
evening. Damaging gusts will be possible if this convection can
organize through the late evening/overnight hours. Model guidance
varies on the intensity and organization of the system. However,
confidence has increased enough that 15% CIG1 wind probabilities
have been added along the front.

...High Plains...
To the southwest along the surface lee trough, high-based convection
is likely to develop around peak heating across southwestern NE into
eastern Co and western KS. Despite more limited surface moisture,
very warm temperatures and steep lapse rates in the lower/middle
troposphere will promote strong multicell clusters. These storms
could produce severe gusts as they move east/northwest eventually
moving into more unstable air.

...Upper TX Coast...
TS Eduardo located near 28.6N 91.8W as of 10 pm CDT is forecast to
move toward the southwest LA/southeast TX coast and make landfall
tonight. Wind fields are forecast to remain relatively confined
given its small size and fast westward motion. This should limit 
stronger low-level shear favorable for supercells and tornadoes.

..Lyons/Wendt.. 09/01/2026

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1258 AM CDT Tue Sep 01 2026

Valid 021200Z - 031200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE EASTERN
GREAT LAKES TO THE MID-ATLANTIC...

...SUMMARY...
Severe thunderstorms are possible across portions of the eastern
Great Lakes to the Mid-Atlantic through the day Wednesday. Severe
gusts are the main threat, though some hail or a tornado or two
could occur. A few severe gusts are also possible over northern
Montana Wednesday afternoon.

...Synopsis...
An upper ridge will stall over the TN Valley, with a low-amplitude
mid-level trough poised to traverse the ridge and overspread
portions of the Northeast tomorrow (Wednesday). Meanwhile, an upper
trough will amplify across the Interior West. At the surface, a
trough will become established across the Hudson Valley area,
promoting enough lift for ascent amid a moist and unstable low-level
airmass, supporting strong to severe thunderstorm development.
Likewise, deep-layer forcing for ascent and colder temperatures
aloft will accompany a pronounced mid-level impulse rotating around
the Interior West upper trough, promoting isolated severe potential
across portions of northern MT.

...Eastern Great Lakes to the Mid-Atlantic...
A complex severe weather setup will exist across the eastern Great
Lakes to the Mid-Atlantic through the entire period (12Z Wednesday
morning to 12Z Thursday morning). Guidance consensus continues to
depict a primary mid-level impulse and accompanying 50+ kt 500 mb
jet max overspreading the Hudson Valley during the day. 70+ F
surface dewpoints beneath 7 C/km mid-level lapse rates will yield
2500+ J/kg MLCAPE from eastern Lower Michigan to at least as far
east as central PA by afternoon peak heating. The overspreading
mid-level jet max will also encourage 40-50 kts of effective bulk
shear and modestly curved, elongated hodographs. Such conditions
will foster the potential for supercells and bowing segments
accompanied by a severe gust threat, along with isolated instances
of large hail and perhaps a tornado or two. 

The primary concern with this meteorological setup will be the
timing and placement of thunderstorm clusters, which will ultimately
determine the severity and coverage of convective hazards. CAMs
widely vary in their solutions regarding the outcome of this event,
with some models showing early day bow echo potential and others
holding off on the main round of storms until after dark. Given the
ambient supporting environment, there may be a need for introducing
higher severe probabilities with CIG1. However, this scenario is
highly dependent on the timing of organized storms relative to the
diurnal cycle, a detail better resolved with a full suite of
convection-allowing guidance. If storms are poorly timed with the
diurnal cycle (including an overturning of the warm sector during
early afternoon), severe probabilities may even need to be reduced
in places. Given the inherent lack of predictability that often
accompanies subtly forced ridging environments, prudence was
exercised in withholding higher severe probabilities this outlook.  

...Portions of northern Montana...
A surface trough will deepen across central and northern MT with the
south-southwestward approach of the mid-level impulse embedded
within broader upper troughing. As this occurs, a band of showers
and thunderstorms will develop along an arcing cold front poised to
sweep across the region. Ahead of the storms/front, surface
temperatures will warm into the 80s F, amid dewpoints at or below 40
F, resulting in a well-mixed boundary layer extending to the 600-500
mb layer. Furthermore, strong unidirectional (southwesterly) flow
through a deep layer will promote 20-30 kts of effective bulk/speed
shear, with multicells the main storm mode expected. Efficient
evaporative cooling (given the deep and dry boundary layer) will
promote the potential for widely scattered severe gusts with the
stronger storms.

..Squitieri.. 09/01/2026

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0220 AM CDT Tue Sep 01 2026

Valid 031200Z - 041200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE EASTERN OHIO VALLEY INTO THE MID-ATLANTIC...

...SUMMARY...
At least widely scattered severe storms, accompanied by damaging
gusts and perhaps some hail, appear likely across portions of the
Ohio Valley to the Mid-Atlantic coast on Thursday.

...Synopsis...
Upper ridging will persist across the Mid-MS Valley and points east,
with multiple mid-level perturbations expected to crest the upper
ridge from the Upper MS Valley to the Mid-Atlantic through the day
Thursday. Currently, the best chance for severe storms will be with
the primary impulse over the Mid-Atlantic, as stronger flow aloft
overspreads a moist boundary layer. A couple of severe thunderstorms
also cannot be ruled out farther northwest across the Upper MS
Valley, where rich low-level moisture will be coincident with a
diffuse warm frontal boundary.

...OH Valley to the Mid-Atlantic Coastline...
Medium-range guidance is in general agreement that a modest
mid-level impulse will overspread the Mid-Atlantic, contributing to
some forcing for ascent and 30-40 kts of effective bulk shear.
Despite only 6 C/km mid-level lapse rates, surface dewpoints
exceeding 70 F will yield over 2000 J/kg MLCAPE from the eastern OH
Valley to the Mid-Atlantic coastline on a widespread basis. While
upper support may be weaker compared to the previous day, multiple
days of preceding storms should leave behind a lingering baroclinic
boundary somewhere around the Mid-Atlantic, which may act as a
forcing mechanism for convective initiation. Given the
aforementioned CAPE/shear parameter space, supercells and bowing
segments may occur, capable of producing mainly a severe gust
threat, though a couple instances of severe hail may occur.  

Some guidance suggests that the best buoyancy/shear parameter space
for severe may situate over eastern PA into NJ. However, it is
unclear how previous day's storms will impact the boundary layer
over this region by Day 3/Thursday, so Slight Risk probabilities
were introduced conservatively, with some latitude given to the
northern extent of the Marginal Risk probabilities. If the more
aggressive guidance holds true and convective overturning does not
dominate this region, higher severe probabilities may be needed in
future outlooks.

...Portions of the Upper MS Valley to the Midwest...
Convective initiation is more uncertain across portions of the
Midwest to the Upper MS Valley, where a northwestward arching warm
front will be located. Here, surface dewpoints should reach the mid
70s F beneath 7 C/km mid-level lapse rates, yielding 3500-4500 J/kg
MLCAPE. While several calibrated ML/AI guidance members depict
higher severe probabilities across this region, only Marginal risk
probabilities have been introduced since the mid-level impulses
poised to track along this boundary are quite small and subtle,
rendering storm coverage highly questionable. Nonetheless, if a
storm can mature and become sustained, 40+ kts of effective bulk
shear with the strong instability may support a supercell or two
capable of mainly severe wind and hail.

..Squitieri.. 09/01/2026