Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Wed Sep 02 2026
Valid 030100Z - 031200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING
ACROSS PARTS OF THE SOUTHERN TIER OF NEW YORK INTO NORTHERN AND
CENTRAL PENNSYLVANIA...
...SUMMARY...
Thunderstorms posing a risk for potentially damaging wind gusts may
continue into late evening across parts of the Southern Tier of New
York into northern and central Pennsylvania.
...01Z Update...
...Great Lakes into Mid Atlantic...
To the south of a modest lower/mid-tropospheric cyclone, now
migrating to the east of James Bay, the leading edge of broad
mid-level troughing is in the process of gradually shifting
east-southeast of the lower Great Lakes region. Forcing for ascent
associated with this feature has contributed to the evolution of an
organizing cluster of storms now spreading across western New York
state, ahead of a southward advancing segment of the surface frontal
zone trailing the cyclone. However, in the wake of an early day
convective cluster, appreciable warm sector boundary-layer
instability is becoming confined to a narrowing corridor across the
Allegheny Plateau. As the ongoing convective system continues
east-southeastward, and the onset of boundary-layer cooling
progresses, more stable southeasterly near-surface updraft inflow
seems likely to weaken convection and reduce the associated risk for
severe weather as it spreads toward northern Mid Atlantic coastal
areas tonight.
Upstream, convection-allowing guidance suggests that forcing for
ascent associated with lower/mid-tropospheric warm advection may
support renewed widely scattered thunderstorm development overnight.
This is mostly likely to focus near/to the cool side of the
stalling trailing frontal zone on the southern fringe of the
westerlies, across southern portions of the Great Lakes into Upper
Midwest. Aided by modest strengthening of westerly flow in excess
of 30 kt around 850 mb, and steep lapse rates of
lower/mid-tropospheric temperature and potential wet-bulb
temperature, there appears potential for one or two upscale growing
clusters which may pose a risk for severe hail and wind.
...Northern Rockies and adjacent Great Plains...
The risk for severe weather has diminished considerably in the wake
of weakening convection now overspreading the Montana international
border. As the supporting vigorous short wave impulse continues to
pivot north of the border into the Canadian Prairies this evening,
this appears unlikely to change. An isolated strong storm to the
east-southeast of Miles City MT does appear supported by updraft
inflow of relatively moist boundary-layer air characterized by
sizable CAPE in excess of 2000 J/kg. However, it is not clear how
long this will be maintained, as inhibition increases with
boundary-layer cooling and perhaps some further warming aloft.
..Kerr.. 09/03/2026
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