Update on Friday Severe Thunderstorm Risk

The Storm Prediction Center has placed the Mid-Atlantic under a Marginal Risk for Severe Thunderstorms on Friday.

Two rounds of precipitation will impact the DC Area, the first associated with the passage of a warm front tomorrow morning and the second associated with a negatively tilted upper-level trough and surface cold front.

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Squall Line Containing Damaging Wind Gusts May Impact the Washington Area Friday Morning

Washington Monument, photo credit Dustin Gaffke

The latest high-resolution North American Model (image above courtesy TropicalTidbits) shows the future-cast radar simulation for Friday between 2AM and NoonIf this latest model verifies regarding timing, then the DC Area would be impacted by gusty winds and torrential rainfall as the squall line pushes through the area between 9AM and Noon. 

Wind shear (winds that change direction with altitude) values will be medium as a powerful jet stream will produce strong southerly winds above the surface while low-level winds will be veering in from the southeastCAPE (Convective Available Potential Energy) will be lacking due to extensive cloud cover and rainfall out ahead of the front.

Bottom line: the squall line (bright red line of thunderstorms in image above) may contain damaging wind gusts with a slight chance of a brief weak tornado.

Rainfall amounts of a half to three-quarters of an inch are likely Thursday evening through predawn Friday with an additional half inch to one inch of rain with the squall lineFlooding concerns at this time appear marginal due to the fact that we are still climbing out of a drought and the fast movement of any thunderstorms.