The Storm Prediction Center (SPC) has placed DC and portions Northern Virginia and Maryland in a “Slight Risk” for Severe Thunderstorms this afternoon, with the main threat being damaging winds in excess of 60mph and hail.
Ingredients for Severe Thunderstorms
Increasing wind shear, steepening low-level lapse rates, dew points in the 70s (oppressive humidity) and temperatures in the 90s will provide the necessary ingredients for numerous thunderstorms to develop this afternoon and evening.
Timing the Storms
The latest high-resolution NAM model shows a nasty line of storms forming over the Shenandoah Valley around 2pm and then racing eastward across the Washington and Baltimore Metropolitan Areas between 4 and 7pm.
Storms may also produce torrential rainfall rates of 1 to 2 inches per hour causing flooding of low lying areas, underpasses and cause creeks and streams to rapidly rise out of their banks. Because of this the National Weather Service has issued a Flood Watch for portions of the DMV.