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Posted at 12:33 PM ET, 09/08/2012

Severe storms, confirmed tornado roll through D.C. area.; more tranquil weather moving in

Update, 6:10 p.m.: The severe thunderstorm watch has been discontinued for the entire D.C. region except Calvert and St. Mary’s county where some strong storms remain possible for the next couple of hours. Along/east of I-95 scattered showers are possible through 8-10 p.m. To the west, just an isolated shower or two may linger, but partial clearing should gradually commence if it hasn’t already.

For more on the storm, follow the Post’s storm news blog and interactive power outage tracker.

Update, 5:50 p.m.: Showers may linger as late as around 8 p.m., especially the further south and east you are. After that, we’re well on our way to a gorgeous stretch of warm fall weather. See our delicious forecast for tomorrow into the work week.

Update, 5:20 p.m.: The Washington Post storm impacts live blog reports that trees fell onto two townhouses and an apartment complex not far from where a tornado was spotted in the Reston-Herndon area around 4:30 p.m., and that high winds have closed the Bay Bridge.

Some other storm impacts from around the area include a tree down near National Airport; wind gusts near 69 mph in Ashburn and near 60 mph in Quantico, Glenn Dale, Morningside, Beltsville, Gaithersburg, Chantilly, and near Dulles Airport and National Airport; downed power lines in NW DC (pic); downed trees in Alexandria (pic) and Silver Spring (pic); a collapsed building that was under construction in NE DC (pic). Also, in­cred­ibly, the storms dropped the temperatures at Dulles 25 degrees in less than 1 hour (from 89F to 64F between 3 and 4 p.m.). The storms have also left thousands without power, and halted the Nationals game in the bottom of the 9th (pic) with the Nats down a run.

Update, 5:05 p.m.: Currently no warnings are in effect across the area except for the Flash Flood Warning for D.C. proper until 6:30 p.m., where continuing showers mean a continuing concern for flooding.

Update, 4:50 p.m.: Collective sigh of relief as all Tornado Warnings have expired. Storms still stretch across most of the southern and eastern parts of the area, and the risk of showers and storms continues a few more hours for everyone, but the severe threat is starting to diminish.

Update, 4:35 p.m.: Severe storms continue to advance east across the area. One TORNADO WARNING remains in effect until 4:45 p.m. in southeast Anne Arundel County. In path of this storm: Londontowne, Selby-on-the-Bay, Shady Side. Elsewhere we have a Severe Thunderstorm Warning for eastern parts of the area until 5:15 p.m., from just east of I-95 to the Bay. Destructive winds to 70 mph+ continue to be a concern with these storms. Things calming down now for areas north and west of the Beltway, though a Flash Flood Warning remains in effect until 6:30 p.m. for D.C. proper.

See earlier updates lower down in this post.

Original overview (from 12:30 p.m.): A line of intense thunderstorms approaching from the west has prompted the National Weather Service to issue a Severe Thunderstorm Watch for the entire D.C.-Baltimore area until 10 p.m. Assuming they hold together, which we believe they should, the storms are expected to move west to east across the D.C. metro area between approximately 3 and 8 p.m. Besides lightning, damaging thunderstorm winds (potentially widespread) are the main concern, though there is some risk for tornadoes as well.

Several factors have come together to create the severe potential, including a strong cold front and fast upper-level winds. That said, there’s some chance the worst of the storms occur to our northeast where the severe risk is even greater, especially as you get into northeast Maryland, eastern Pennsylvania, New Jersey and northward into Upstate New York and New England. Tornadoes have been reported in the NYC metro area this morning.

Stay tuned for updates here on this blog, on Twitter and Facebook.

Keep reading for earlier updates...

Update, 4:10 p.m.: The Tornado Warning below has been cancelled. A new TORNADO WARNING covers northeast Prince George’s and central Anne Arundel counties until 4:45 p.m. In path: Prince George’s Stadium, Bowie, Londontowne, Parole, Rhode River, Annapolis, Mayo, South River, Galesville, Shady Side.

Update, 4:05 p.m.: The Tornado Warning in Fairfax County has been cancelled. But the TORNADO WARNING tweeted about above for north Prince George’s County remains in effect til 4:30 p.m. It includes Beltsville, College Park and Greenbelt.

Update, 3:50 p.m.: The National Weather Service reports that A TORNADO HAS BEEN CONFIRMED by county officials near the city of Fairfax, moving east at 50 mph. TORNADO WARNING now til 4:15 p.m. central Fairfax County east to the D.C. line. In path of tornado: Alexandria, Huntington, Crystal City, Ballston, Woodrow Wilson Bridge, Nat’l Airport

Update, 3:45 p.m.: Severe storms with the potential for destructive winds now reaching west branch of Beltway and heading east across entire D.C. metro area over the next few hours. These are dangerous storms so get inside and wait them out. A Severe Thunderstorm Warning covers much of the metro area. In addition a Flash Flood Warning is in effect until 6:30 p.m. for D.C. proper, where an expected 1-2” of rain could cause flooding.

Update: 3:34 p.m.: TORNADO WARNING city of Fairfax and central Fairfax co til 4pm. In path: Chantilly, Oakton, Fairfax, Mantua, Merrifield, I-66 & I-495 Interchange, Annandale, Pimmit Hills. TAKE COVER in interior room now!

Update, 3:15 p.m.: Severe storms capable of damaging winds of 60-70 mph+ continue to advance east toward D.C., now reaching near Leesburg and Manassas. Be prepared to get indoors quickly as these storms track west to east across the area during the next several hours.

Update, 2:58 p.m.: Severe Thunderstorm Warning for most of Loudoun, central/north Fauquier, northwest Prince William, and western Montgomery counties until 4 p.m. Destructive winds to 70mph+ possible with these storms.

Update, 2:55 p.m.: Here’s our best guess on when storms will affect the D.C. area from west to east: 3:30-5:30 p.m. west burbs (Prince William and eastern Loudoun counties east to the west branch of the Beltway); 4:30-6:30 p.m for around, inside and north/south of the Beltway including the District, I-270 corridor to the north and I-95 corridor to the south; 5:30-8:30 p.m. from the east branch of the Beltway east to the Chesapeake Bay.

Update, 2:20 p.m.: Severe Thunderstorm Warning until 3:30 p.m. covers northern Montgomery County (north of Germantown) as well as southeast Frederick and northwest Howard counties. Most of Carroll County too. Quarter-size hail and damaging winds to 60 mph+ are possible. This line is growing to the southwest and may hook up with the line further west along I-81.


Radar at 2 p.m. Screenshot from postweather.com
Update, 2:05 p.m.: The line of storms expected to impact the immediate metro area from west to east around 3-9 p.m. is taking shape along and west of I-81 as seen in the radar picture to the right taken at 2 p.m. It may grow and hook up with the line northwest of Montgomery County.

Update, 1:20 p.m.: This initial push of storms has veered north of the immediate metro area, primarily affecting Frederick and Carroll counties and northern Loudoun County. Probably after ~3 p.m. until the storm risk goes up for areas closer to D.C.

Update, 1:15 p.m.: The Tornado Warning around Hagerstown has been cancelled. But a Severe Thunderstorm Warning is in effect until 2:15 p.m. for most of Frederick and Carroll counties. Widespread damaging winds are possible with the intense storms moving from west to east through those areas.

Update, 12:55 p.m.: A Tornado Warning is in effect until 1:15 p.m. for NE Washington co in north central Maryland. This includes the Hagerstown area. NWS says the tornado may be wrapped in rain and hard to see.

By  |  12:33 PM ET, 09/08/2012

 
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