038
ACUS02 KWNS 010600
SWODY2
SPC AC 010558

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

$$