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Posted at 01:07 PM ET, 08/21/2011

Evening storm chances down but not out

Power outage summary

6:55 UPDATE: Radar across the area and to the immediate west has cleared out nicely behind the earlier storms. The Severe T’storm Watch and Flash Flood Watch have both been cancelled, and rain chances appear low over the next couple hours. There’s still an area of storminess in Western Maryland that bears watching for late evening, and a few storms could still pop up in the meantime. Overall, the chance of rain from now into the overnight is down to around 30-40%. Follow live updates on our Twitter feed above as needed.

4:05 UPDATE: Storms have largely now exited the District and are continuing eastward through Prince George’s, Charles, and Anne Arundel counties towards the Bay. Heavy rain and gusty winds accompanies much of this activity where a severe thunderstorm warning is in effect until 4:45 p.m.. To the west of where storms are now (and after 4:30-5:00 p.m. where storms are now) we’re likely to have a break in the action until at least 6:00, when another round may move in from the west. The National Weather Service cautions more severe weather may develop between 6 and 9 p.m. (from west to east).

3:45 UPDATE: The worst of the storms have crossed I-95 in Maryland, with heavy activity in central to northeast Prince George’s county into central and northern Anne Arundel county. Thunderstorms activity also extends from southeast DC into eastern Prince William and Stafford counties . All of this activity continues pressing eastward towards southern Maryland and the Bay.

3:15 UPDATE: Severe thunderstorm warnings have been issued for eastern Arlington, the District, central Prince George’s and southeast Montgomery counties. Line of strong storms stretches from Falls Church to Laurel and is headed east northeast.

Earlier updates

Overview from 1 p.m: The Storm Prediction Center in Norman, Oklahoma has issued a severe thunderstorm watch for a large portion of the mid-Atlantic and Northeast. Storms are already developing in the region and are likely to increase in coverage and intensity through the afternoon. Dangerous lightning, damaging wind gusts and hail are possible in storms that develop. A Flash Flood Watch is also in effect due to the possibility of slow moving storms and heavy rain.

Keep reading for technical discussion and earlier updates...

Technical discussion from the Storm Prediction Center:

DISCUSSION...THUNDERSTORMS WILL INCREASE IN COVERAGE/INTENSITY THIS AFTERNOON IN CONJUNCTION WITH CONTINUED DAYTIME HEATING...AND AS A MIDLEVEL TROUGH AND COLD FRONT MOVE EWD/SEWD ACROSS THE REGION. ADDITIONALLY...A SURFACE LEE TROUGH FROM NRN VA TO ERN PA/SE NY WILL HELP FOCUS THUNDERSTORM DEVELOPMENT. MODERATE-STRONG INSTABILITY/MLCAPE AOA 2000 J PER KG/ AND INCREASING VERTICAL SHEAR THROUGH THE AFTERNOON WILL BE FAVORABLE FOR STORMS TO PRODUCE DAMAGING WINDS AND LARGE HAIL. A COUPLE OF SUPERCELLS MAY ALSO DEVELOP THIS AFTERNOON NEAR THE LEE TROUGH...AND AN ISOLATED TORNADO WILL BE POSSIBLE WHERE LOW-LEVEL SHEAR WILL BE SOMEWHAT STRONGER.

Earlier updates

2:45 UPDATE: Storms have developed over northern and northeast Fairfax county, Montgomery county into Howard county, but are not severe at the moment (though they could turn severe). They’re producing very heavy rain and some gusty winds and could intensify as they move east/northeast .

2:00 UPDATE: Severe weather is impacting the northeast suburbs - especially northern Anne Arundel county and Baltimore where severe thunderstorm warnings are in effect through arond 2:30-2:45. In Baltimore, torrential rain has also prompted a flash flood warning. Importantly, a tornado warning is in effect for a small sliver of northeast Anne Arundel county until 2:30.

Also, multiple severe thunderstorms warnings are in effect for D.C.’s western suburbs through 2:30, including western Fairfax, western Montgomery, much of Loudoun, central Fauquier and northwest Prince William counties. These storms are very likely to move into the immediate metro region (inside the beltway) between about 3 and 4 p.m. Torrential rain is likely along with the possibility of damaging wind and hail.

By  |  01:07 PM ET, 08/21/2011

Categories:  Latest, Thunderstorms

 
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