Additional storms develop in a broken line from near Westminster to southwest of Culpeper. The storm will move fairly quickly to the east over the next few hours.
15.00 — Severe thunderstorms until 21.00 for the entire area
The Storm Prediction Center has issued a severe thunderstorm watch. It runs until 21.00. Developing storms will move into the western parts of the area over the next 30 to 60 minutes, then move eastward into the early evening.
Thunderstorms are emerging near the Interstate 81 corridor. High humidity and rising heat have helped create strong instability east of the Appalachians, which will provide ample fuel for storms as they move into the area.
The main severe weather threat with these storms will be isolated to scattered damaging wind gusts as high as 60 to 70 mph. Spotted hail up to an inch in diameter is possible, as is a brief tornado, especially northeast of the local area.
Original post from 14…
Thunderstorms are starting to develop as we look at the 2:30 PM to 7 PM time window for the region – maybe 3 PM to 5 PM directly around the Beltway. Any given location may only see about a 1-2 hour storm as any broken line of storms should move quickly. Should any strong storms break out, their primary threat would be damaging wind gusts above 57 mph. The rain should help cool us down after some mid to upper 90s in the region.
For tonight: The heaviest storms should taper off fairly quickly after dark, but keep in mind that we can’t rule out some short-lived very heavy downpours, a “breakdown” wind potential from a few stronger storms, some intense lightning, and even some hail.
A few showers or weaker storms may continue towards, but not past midnight. Low temperatures won’t drop much yet as they bottom out in the humid low to mid 70s.
See weather at The Washington Post.
Tomorrow (Sunday): The air is a bit more pleasant, but we cannot rule out a small chance of rain. Clouds, showers and even a quick storm may be around at times in the morning. We should see some breaks of sunshine. High temperatures in the 83-88 degree range don’t feel so bad as dew points drop below balmy levels. We can thank light northwest winds for bringing in more dry air. A few thunderstorms may also develop in the mid to late afternoon.
During the night we have a small chance of isolated showers and storms that may wander into the early morning hours. The sky is generally partly cloudy. Low temperatures aim for the upper 60s to low 70s as humidity drops a bit.
Thunderstorms expected today as the cold front approaches
While we don’t have a high chance of seeing a severe thunderstorm issued for the area, it is possible. There are ingredients for a few strong thunderstorms as a slowly approaching cold front and low-pressure system moves into our area.
As these approach and move eastward, we get some atmospheric “lift” that helps our moist air condense into clouds as the air is forced to rise – and those clouds are likely to be concentrated into some thunderstorms. We also have a bit of instability and spin above us, shaded here in light orange:
Despite these ingredients of lift and instability, we think storm coverage could be sparse and target the Beltway within the 10 a.m. time frame. 15 to 18. This is how they may first appear on radar:
These simulated radar images from the North American (NAM) weather model start thunderstorm cells over the DMV (somewhat spotty at first) with some intensification and greater coverage as they sink to our southeast into the early evening:
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