Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0300 PM CDT Wed Sep 02 2026
Valid 022000Z - 031200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WESTERN NEW YORK...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
MONTANA...
...SUMMARY...
Scattered to numerous severe thunderstorms are likely across parts
of the Great Lakes to the Mid-Atlantic this afternoon through
tonight. Damaging winds are the main threat, though some large hail
and a few tornadoes may also occur. Scattered severe gusts and
isolated large hail appear possible over the northern Rockies/High
Plains this afternoon and evening.
...20Z Update...
The Enhanced Risk in NY was expanded slightly eastward, driven by
45-percent wind probabilities. Here, temperatures are gradually
warming into the upper 70s to lower 80s (higher than earlier
guidance suggested). This will yield a corridor of moderate
surface-based buoyancy ahead of developing storms this afternoon.
Strong deep-layer shear oriented favorably to an expected cluster of
storms and the destabilizing air mass should support a swath of wind
damage (supported by the latest time-lagged HRRR/RRFS ensemble
guidance). For additional details, see MCD 2201.
Farther west, severe probabilities were trimmed behind a strongly
forced, northeastward-moving band of convection in the northern
Rockies. For details on the near-term severe threat, see MCD 2200
and Severe Thunderstorm Watch 644.
..Weinman.. 09/02/2026
.PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Sep 02 2026/
...Lower Michigan into the Mid-Atlantic...
An ongoing cluster across south-central PA has a well established
cold pool and a history of producing damaging winds across
western/central PA. This convection is expected to continue moving
quickly southeastward through the afternoon across parts of
MD/DC/northern VA and vicinity. There is still some uncertainty on
whether this cluster will be able to maintain intensity with
southward extent into the Mid-Atlantic, as it becomes increasingly
removed from the stronger forcing aloft/mid-level flow over the
Great Lakes into NY. Still, a differential heating zone remains
apparent along/near the Chesapeake Bay per recent visible satellite
imagery and surface observations. The cluster should tend to remain
on the warm side of this boundary, with steepening low-level lapse
rates developing as daytime heating continues to destabilize the
downstream airmass. Scattered damaging winds will likely remain a
threat with these thunderstorms as they track across the southern
Mid-Atlantic before eventually weakening.
In the wake of this late morning/early afternoon activity, it
appears likely that robust destabilization will occur across parts
of lower MI into western NY. 12Z observed soundings from APX/DTX/BUF
showed moderate to very strong MUCAPE and modestly steepened
mid-level lapse rates with an EML. This favorable airmass will
spread eastward through the day in tandem with a mid-level shortwave
trough and 50-60 kt mid-level jet also advancing eastward over the
Great Lakes and ON. Even with some cloud cover present, moderate to
strong instability will likely be in place across western NY by late
afternoon, to the west of a differential heating zone/front.
Thunderstorms are expected to develop along/ahead of a cold front
from parts of southeast Lower MI to the lower Great Lakes, with 50+
kt of deep-layer shear supporting organized updrafts. A mix of
supercells and multicells will likely pose a threat for both severe
hail and scattered to numerous damaging winds. Sufficient low-level
shear should also be present to support a few tornadoes, with some
chance for a strong tornado this evening if a supercell mode can be
maintained across western NY and vicinity. Confidence has increased
in a corridor of greater severe/damaging wind potential late this
afternoon/evening across parts of western NY, where an Enhanced Risk
has been introduced.
...Northern Rockies/High Plains...
High-based thunderstorms have already developed over the higher
terrain of central ID this morning. Enhanced winds aloft associated
with a northeastward-ejecting mid-level shortwave trough and steep
low-level lapse rates will support a risk for scattered
severe/damaging winds as this activity spreads northeastward across
MT this afternoon and evening. Occasional 75+ mph gusts may occur,
even though instability should remain weak. Isolated thunderstorms
may also develop later this evening/tonight in a low-level warm
advection regime across eastern MT into western ND, with some hail
threat.
...Eastern Utah into the Central Rockies/High Plains...
Thunderstorms are expected to increase in coverage this afternoon
over eastern UT into the higher terrain of northern/western CO and
southern WY. This activity will spread northeastward into eastern
WY/western NE where a very deep/well-mixed boundary layer should
support locally severe gusts.
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