11:30 a.m. update, July 1: We have a detailed, comprehensive recap of this event just published: D.C. endures worst storm since Derecho 2012 — here’s how it happened
That's the first time I've been legitimately frightened by a storm since I moved out to DC 10 yrs ago. That was bonkers. @capitalweather— Nicole M. Rice (@NicoleMWrites) July 1, 2015
@capitalweather - that was very intense here in so. fx. co. Crazy wind, thunder, lightning and rain like I haven't seen since a hurricane!— l alcock (@sixthoftwelve) July 1, 2015
Many people on Twitter commented this was the most intense and scary storm they’ve witnessed in some time. They said they’ve never seen such a lightning display. We’ll have an explainer on what happened in the morning. Stay safe.
12:30 a.m. update, July 1: Radar show intense thunderstorms moving into the area from the south and southwest and severe thunderstorm warnings have been issued for our southern suburbs and I expect them to be expanded north. These storms are producing extremely heavy rain, very frequent lightning and thunder and strong winds. Isolated damaging wind gusts and flash flooding are both possible as these storms cycle through the entire metro area over the next couple of hours, from southwest to northeast.
Follow the progress of the storms on the radar above. For the latest warnings, follow our Twitter alert feed: @dcweatheralerts or the National Weather Service.
8:30 p.m. update: Local radar remains quiet over the area, but we’re still thinking some showers and storms with heavy downpours have a good chance to move through the area between 11 p.m. and 3 a.m. Regional radar continues to show an area of storminess working through West Virginia and short-term modeling shows it affecting the immediate area by midnight.
6:45 p.m. update: As storms have not developed in the area this evening, the severe thunderstorm watch has been canceled. However, showers and storms may move in later tonight between about 11 p.m. and 3 a.m., per the update below. We’ll have an update on those storms later – between 8 and 8:30 p.m.
6:00 p.m. update: It’s looking increasingly likely that, although an isolated storm could pop up, most of the immediate metro area will not experience storms early this evening. Storms will be a bit more prevalent in our far northern suburbs from northern Loudoun County to Frederick County to Carroll County
Of greater interest is a line of storms entering West Virginia that could affect the region between about 11 p.m. and 3 a.m. It could produce some heavy rain and gusty winds coming through. Severe weather expert Jeff Halverson says some may wonder if it’s a derecho but assures us it is not. It doesn’t have a history of widespread damaging winds, isn’t moving as fast as a derecho and environmental conditions don’t support a derecho.
We’ll keep an eye on this storm complex and will post our next update around 8 p.m., or sooner if needed.
4:40 p.m. update: Storm coverage is widely scattered to isolated and it’s possible parts if not most of the immediate metro area avoid storms the next few hours, at least. A cluster of storms in northwest Virginia and the eastern panhandle of West Virginia has eyes set on Frederick County, Md between now and about 6 p.m. Otherwise, there’s not much out there although isolated storms could pop up pretty much anywhere in the region. Showers and storms may become more numerous overnight.
- Storm timing, coverage: Isolated to widely scattered storms between 5-9 p.m., more coverage north of the Beltway
- Storm motion: Southwest to northeast
- Likely storm hazards: Downpours, lightning, gusty winds
- Possible storm hazards: Damaging winds, small hail, brief-small tornadoes
- Rainfall forecast: No rain to a quick inch in the heaviest localized downpours
- Confidence: Low-Medium – Biggest uncertainty is storm coverage; it’s possible this is a non-event for some or even many areas, especially south of the District
3:40 p.m. update: Storms are starting to fire along the I-81 corridor, though nothing severe at this time. As the storms move east-northeast towards the D.C. area they may increase some in intensity. Most likely timing for the arrival of these storms is between about 5 and 8 p.m. from west to east – although we still think they will be hit or miss rather than widespread.
Incredibly, almost the entire Southeast and Mid-Atlantic is under a severe thunderstorm watch through this evening. I don’t think I’ve ever seen a watch area this large (although size in this case is not an indication of intensity or coverage of severe storms – which we expect to be widely scattered rather than widespread):
Severe T-storm watches stretch from the Ohio Valley to nearly the Atlantic and the Gulf Coast to NY pic.twitter.com/Y7EdgTlffw— Jordan Tessler (@TerpWeather) June 30, 2015
2:40 p.m. update: The National Weather Service Storm Prediction Center (SPC) has issued a new severe thunderstorm watch, covering the D.C. metro area and its southern suburbs through 9 p.m. This watch is in addition to the watch issued earlier for D.C.’s northern suburbs and Baltimore, in effect through 8 p.m.
SPC expects storms to initiate over eastern West Virginia and western Virginia shortly, some of which may become severe with damaging winds and hail as they move east.
We still believe storm coverage from D.C. and points south will be less compared to our northern suburbs and especially into Pennsylvania.
Original post from 1:30 p.m.
Scattered thunderstorms may develop in the region this afternoon, and a couple could turn severe. The best chance of severe storms, capable of producing damaging winds and hail, lies in D.C.’s northern suburbs where a severe thunderstorm watch is in effect through 8 p.m.
The watch includes Anne Arundel and Howard counties and points north.
The most likely timing for storms is late this afternoon and early this evening. Storms will tend to be hit or miss, with decreasing coverage south of the District.
There’s enough atmospheric instability and wind shear to support some isolated severe storms, especially in our northern suburbs into early this evening.
The National Weather Service Storm Prediction Center say there’s about a 50 percent chance of at least 10 damaging wind and 10 large hail reports in the severe thunderstorm watch area, and a 20 percent chance of two or more tornadoes.
To the south, radar and computer model forecasts indicate more isolated activity. However, a severe thunderstorm watch may still be issued, according to the National Weather Service Storm Prediction Center. It says there’s sufficient wind shear and atmospheric instability (CAPE is over 2,000) to support severe storms, but some uncertainty as to how widespread storms will become.
Short-range modeling shows the best potential for storms in the 5 p.m. timeframe right around Washington, D.C.
“Anything that does get going, should rapidly organize into strong multicell structures, with splitting supercells not out of the question south and east of D.C.,” said Jeff Halverson, Capital Weather Gang’s severe weather expert. “But I think the better forcing [for storms] is over Pennsylvania.”