Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Sep 05 2025 17:33:47

ACUS02 KWNS 051733
SWODY2
SPC AC 051732

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1232 PM CDT Fri Sep 05 2025

Valid 061200Z - 071200Z

....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN
PENNSYLVANIA AND NEW JERSEY NORTHEASTWARD INTO FAR SOUTHERN MAINE...

....SUMMARY...
Scattered strong to severe thunderstorms are most likely Saturday
from eastern Pennsylvania and New Jersey into parts of southern New
England. Isolated strong gusts are possible extending southward
across the Piedmont.

....Synopsis...
A leading mid/upper level speed max will pivot northeastward across
Quebec on Saturday, with the right-entrance region sweeping across
much of the northeastern states. Given the trajectory, only subtle
height falls will occur over the region, but midlevel southwest
winds will increase to around 60 kt, enhancing deep-layer shear.

This cyclonic pattern aloft will extend well south across the
Appalachians, where winds will be much weaker. However, relatively
cool midlevel temperatures will aid destabilization in these areas.

At the surface, a cold front will push east from ME into northern
VA, with a moist air mass ahead of it. Winds at 850 mb will increase
to 30-40 kt across the Northeast, which will aid the northward
transport of moisture and destabilization.

....Northeast...
A wave of low pressure is forecast to develop over eastern PA early
in the day, translating northeastward along the front and into ME by
late afternoon. Stronger heating and steep low-level lapse rates
should develop from VA into eastern PA/NJ and into interior southern
New England, with MLCAPE around 1500 J/kg as an areal average.

As the warm air mass develops and accelerates north ahead of the
cold front, both instability and shear parameter space will become
favorable for severe storms, including supercell potential. A line
of storms is expected by 17 to 18Z, from eastern PA toward the
Hudson Valley, expanding N/S and pushing east through the afternoon.
Given 40-50 kt effective deep-layer shear and enhanced low-level
shear with the midday surface theta-e surge, the initial storm mode
may be cellular along the boundary, with a brief tornado or two
possible along with some hail. Damaging winds are then most likely
as outflows merge, and spread east across the remainder of the
region through late afternoon.

....Piedmont...
Strong heating will occur across most of the area, with areas of
high-level clouds expected across the Appalachians. The
moist/uncapped air mass and weak surface trough should yield
scattered afternoon storms. Despite weak shear, favorable timing
with peak heating/steep boundary layer lapse rates as well as up to
2000 J/kg MUCAPE may yield locally strong to damaging downbursts. A
few storms could produce marginal hail given sufficient longevity.

...Jewell.. 09/05/2025

$$

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