A summertime air mass has returned to the region and a cold front lurks not far to the north. As the front slowly sinks south this evening and a little wave of low pressure rides along it, a cluster of thunderstorms may develop. The best chance of storms lies in D.C.’s northern suburbs up to around the Mason Dixon line.
The National Weather Service (NWS) Storm Prediction Center has placed our region under a slight risk of severe thunderstorms. It writes the environment is “supportive of some storm organization with the primary hazard being damaging wind gusts.” There’s about a 15 percent chance of severe wind gusts (over 58 mph) within 25 miles of a point in our region, its hazard graphics indicate.
Our local NWS office in Sterling says a widespread severe thunderstorm outbreak is not expected but that isolated storms could produce strong gusts.
Most activity probably will occur after dark, but perhaps starting in some of our western areas (Loudoun and Frederick county) as early as 5 or 6 p.m. Generally, I’d highlight the 6 p.m. to midnight window for most rainfall associated with showers and thunderstorms that develop.
Rainfall potential - generally - is about 0.25-0.5”, but locally heavy amounts to 1” or so are possible, especially north and northwest of the District.
Tonight’s storms may be similar in intensity to last night’s although the rain may be more widespread and longer in duration.