ACUS02 KWNS 030554
SWODY2
SPC AC 030553

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1253 AM CDT Wed Sep 03 2025

Valid 041200Z - 051200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN
TENNESSEE NORTHWARD INTO NORTHERN NEW YORK...

...SUMMARY...
Scattered strong thunderstorms may impact a corridor from east
Tennessee northward to the US-Canadian border across northern New
York on Thursday, accompanied by a risk for potentially damaging
wind gusts.

... Synopsis ...

A highly amplified midlevel pattern will continue through
Thursday/Day-2 as a large ridge pushes north through western Canada
and a downstream trough persists across much of the eastern United
States. Within this amplified pattern, a seasonably cold midlevel
low will exist across Ontario, with multiple lobes of vorticity
rotating around the low. One such vorticity lobe/shortwave trough
will move east across the Great Lakes bringing with it increasing
ascent across portions of the eastern US.

At the surface, a cold front associated with the midlevel shortwave
trough will stretch through the Plains east-northeast into the lower
Great Lakes at the start of the forecast period. This cold front
will make slow progress southward across the Plains and faster
progress east across the eastern Great Lakes region.

... East Tennessee northward into Upstate New York ...

Seasonable moisture will be in place across the region ahead of the
advancing surface cold front. Diurnal heating of this airmass should
result in pockets of most-unstable CAPE up to 1500 J/kg to develop
by early afternoon across southern portions of the region to perhaps
750 J/kg across northern portions of the area.

Thunderstorms, or their remnants, ongoing across portions of eastern
Ohio and western Pennsylvania at the start of the period, should
weaken/dissipate through the morning as they move east. These
showers/storms or their outflow may provide potential foci for
thunderstorm development/intensification during the afternoon. To
the west, increasing large scale ascent associated with the
shortwave trough and low-level convergence along the surface cold
front should support additional bands of thunderstorms.

The best thermodynamics will reside across Tennessee and adjacent
areas, with the best deep-layer shear displaced to the north across
northern Pennsylvania and New York. However, the joint distribution
of forecast profiles of shear and buoyancy should favor thunderstorm
organization into small multicell clusters or small linear segments,
with the strongest of these capable of some damaging wind potential.

..Marsh.. 09/03/2025

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