Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CDT Wed Sep 02 2026
Valid 021200Z - 031200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
AND CENTRAL MT AND FROM THE LOWER GREAT LAKES TO THE MID ATLANTIC...
...SUMMARY...
Severe thunderstorms are possible across portions of the eastern
Great Lakes to the Mid-Atlantic today and tonight. Damaging wind
gusts are the main threat, though some large hail and a few
tornadoes may also occur. Scattered severe gusts and more sporadic
occurrences of large hail appear possible from the northern Rockies
into northern High Plains Wednesday afternoon into night.
...Eastern Great Lakes, Mid Atlantic...
Several low-amplitude impulses embedded within a belt of moderate
mid-level northwest flow of 40-60 kt will move from the lower Great
Lakes into the northeast and Mid Atlantic today and tonight. A
surface low over James bay will trail a slow moving cold front to
the southwest across lower ON, the lakes and into MI/OH with a
second backdoor front stalled across the eastern Hudson Valley and
southern new England. Within the warm sector, a very moist air mass
will be in place over much of the Northeast contributing to large
buoyancy and broad, but uncertain potential for severe thunderstorms
much of the day.
A complex convective scenario is expected across the region
modulated by several rounds of thunderstorms beginning early this
morning. Convection associated with a lead shortwave trough exiting
southern ON will likely support scattered storms along the front
across the lower Great Lakes and NY this morning. Isolated large
hail and damaging winds are possible with these storms as they move
southeastward and encounter a gradually destabilizing air mass
across southern PA and possibly into VA/MD.
Air mass recovery is expected behind this initial condition as the
primary upper trough moves from WI and lower MI into western NY/PA
later in the afternoon. Steep mid-level lapse rates of 7-7.5 C/km
atop boundary layer dewpoints in the upper 60s to low 70s will aide
in destabilization with upwards of 2000-3000+ J/kg of MLCAPE by
afternoon from lower MI into western parts of NY and PA. Storm
development is expected ahead of the approaching trough and cold
front as well as on any residual outflow from the morning storms. A
mix of supercells and line segments is expected with all hazards
possible.
A greater tornado risk may evolve in the evening across southern NY
and central PA, contingent upon air mass recovery in the wake of the
prior storms and presence of a more supercellular mode. NAM/RAP
forecast soundings do show some elongation of low-level hodographs,
and any modifying old pool or outflow boundary could further enhance
low-level shear profiles favorable for tornadoes. Higher tornado
probabilities were considered, but uncertainty on the aforementioned
factors remains large.
...MT/ND...
A compact but strong shortwave trough is forecast to move rapidly
northeastward from the Great Basin to the northern Rockies today and
tonight. 35-50 kt mid-level flow will accompany this feature and
overspread a modestly moist, but warm and unstable air mass across
much of central and eastern MT. Ascent from the approaching
shortwave trough will aid in the development of thunderstorms across
the higher terrain of western MT through the afternoon. Despite
modest buoyancy, steep lapse rate profiles and a deep, well-mixed
boundary layer, will enhance severe-wind-gust potential with these
storms. 30-40 kt of deep-layer shear will promote organization and
clustering with some guidance showing a fast-moving line developing
and moving northeastward through the later afternoon/early evening.
Scattered severe gusts are likely, with peak intensity of 65-80 mph
possible.
Additional storms are possible across portions of eastern MT into
the evening within a zone of warm advection along a nocturnally
strengthening low-level jet. Isolated large hail appears to be the
primary hazard with those storms.
...WY...
Some model guidance shows high-based showers and thunderstorms
developing near the southern fringes of the northern Rockies trough
across WY this afternoon. Modest low-level moisture/buoyancy may
limit convective intensity, but sporadic strong outflow gusts are
possible given a very deeply mixed boundary layer.
...Mid MO Valley into IA and southern MN...
An intensifying low-level jet will likely support an increase in
thunderstorms late this evening/overnight across the MO valley and
parts of the Midwest. Moderate to strong elevated instability and
sufficient vertical shear may exist for a few stronger storms
capable of marginal severe hail. However, overall forcing for ascent
is modest and with building mid-level heights, confidence in a
broader organized severe threat is low.
..Lyons/Wendt.. 09/02/2026
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