Thursday, June 21, 2012

Slight Risk Of Severe Weather Tomorrow

With an approaching cool front working into a very warm to hot airmass, thunderstorms are going to be possible in and around the region tomorrow.  With the heat and some humidity in place, some of those storms will have the potential to become strong if not severe.  The Storm Prediction Center has our region under a slight risk for severe weather for Friday.  Given the amount of warmth aloft and very high freezing levels in the atmosphere, large hail does not seem like a likely culprit within the strongest of storms.  However, because of the mixing of dry air and the low level moisture...the differential of airmass and some varying wind direction with height within the atmosphere yields the potential for gusty winds and downbursts within the strongest of storms.

The higher resolution NAM from Penn State paints the potential as being greatest in the afternoon and early evening hours -- the above graphic is for 8 PM Friday night, showing the potential for some clusters of thunderstorms around the East Coast from Southern New England down through the Delmarva.   Storms could be an issue as early as early afternoon on Friday as the frontal boundary approaches and a trough develops downwind from the front along the Appalachian Mountains.  This "heat" trough is typical on hot days in the summer and can serve as a focus for thunderstorm development.  Storms will develop near/along the front and push east, likely scattered in nature through the course of the afternoon.  Not everyone gets thunderstorms but those that do could run the risk of seeing some strong storms and heavy rainfall.