Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1018 AM CST Sun Dec 03 2023
Valid 031630Z - 041200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER PORTIONS OF WESTERN PENNSYLVANIA AND VICINITY...
...SUMMARY...
Isolated, marginally severe thunderstorms are possible over western
Pennsylvania and vicinity this afternoon.
...Upper OH Valley...
Morning water vapor imagery shows a fast-moving intense shortwave
trough over central IL. This feature will become negatively tilted
this afternoon as it races eastward into parts of OH/PA/NY. A
strong mid/upper level jet is associated with this system, with 90+
knot winds at 500mb and 150+ knots at 300mb providing significant
mesoscale forcing in the left-front quad of the jet as it tracks
into western PA around peak heating. Most 12z models show the
development of scattered fast-moving showers and isolated
thunderstorms later today (mainly 20-01z), but luckily
thermodynamics are expected to be quite weak (CAPE values generally
200-500 J/kg and dewpoints only around 50F). The combination of
very steep mid-level lapse rates, ambient vorticity, and strong lift
could result in funnel clouds or a brief tornado from this
convection, along with small hail and gusty winds. However, the
overall severe threat appears marginal due to the weak instability.
..Hart/Lyons.. 12/03/2023
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