An extremely moist atmosphere, temperatures climbing into the low to mid-90s, and an approaching cold front are combining for a severe storm threat in the D.C. region today during the late afternoon and evening. The National Weather Service has issued a severe thunderstorm watch until 11 p.m..
In part because the atmosphere is so moist today, with dew points in the tropical-like mid-70s, many locations have a decent chance of seeing at least one heavy storm. However, some spots could get missed, especially those farther north and west of the Beltway.
It’s less certain how many storms will produce damaging wind gusts or large hail, because that depends on whether sunshine emerged early enough in the afternoon to fuel the atmosphere. Locations that get at least one storm could pick up around 0.5 to 1.5 inches of rain, which would be helpful since rainfall is running more than 3 inches below average since June 1. Other places may see much less rain today.
“The high-resolution forecast models early this afternoon portray a line of storms firing across Montgomery County, the District and Northern Virginia in the late afternoon and sliding east. A second line may develop across the same general region during the evening.,” said Capital Weather Gang’s severe weather expert, Jeff Halverson. “These lines are being triggered by an advancing cold front plowing into a very moist and unstable air mass, which could lead to isolated strong to severe wind gusts, a flash flood threat and potentially more than one round of storms in some places.”
