TL/DR –
A severe storm warning has been issued for northeastern Montgomery and Howard counties, with heavy rain, lightning, damaging winds, large hail, isolated flooding, and a small chance of tornadoes expected. Atmospheric conditions, including high moisture levels and temperatures in the low to mid-90s, are contributing to the severe storm threat, with the National Weather Service issuing a severe thunderstorm watch until 11 PM. The storms are reportedly intensifying due to an approaching cold front, putting areas like Montgomery County, the District, and Northern Virginia at risk of severe wind gusts, flash floods, and potentially multiple rounds of storms.
Severe Storm Warnings for Northeastern Montgomery and Howard Counties
At 4:30 p.m., a severe storm warning was issued for northeastern Montgomery and Howard counties. While the number of storms is few, their intensity is high. A specific warning was issued for a storm near Damascus, expected to travel east and southeast until 5:15 p.m. A recent report mentioned a fallen tree in Urbana. Other storms are beginning to form in the immediate area.
Severe Storm Threat in D.C. Region
An extremely moist atmosphere, temperatures in the low to mid-90s, and an approaching cold front are all elements combining to create a severe storm threat in the D.C. region today. The National Weather Service has issued a severe thunderstorm watch in effect until 11 p.m.
Uncertainty of Damaging Storms
Given the atmospheric conditions, many locations have a high chance of experiencing at least one heavy storm, especially those farther south and east of the Beltway. However, it’s uncertain how many storms will produce damaging wind gusts or large hail, as this depends on the level of sunshine earlier in the day to energize the atmosphere. Any storm could produce around 0.5 to 1.5 inches of rain, much-needed due to the current rainfall deficit of 3 inches since June 1.
Storm Timing, Duration, and Impacts
Off-and-on scattered storms are expected from about 10 p.m., with any individual storm lasting up to 45 minutes. Possible impacts include heavy rain, lightning, damaging winds, large hail, isolated flooding, and a small chance of a tornado. It’s less certain how many storms will produce damaging wind gusts or large hail, but several could.
Predictions from Weather Experts
Capital Weather Gang’s severe weather expert, Jeff Halverson, illustrated a prediction of storms firing across Montgomery County, the District, and Northern Virginia in the late afternoon, moving east. A secondary line may develop across the same general region during the evening. These storm lines, triggered by an advancing cold front into a very moist and unstable air mass, may lead to isolated strong to severe wind gusts, a flash flood threat, and potentially more than one round of storms in some places.
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