Related: Viewer imagery from the storms
6:45 p.m. update and forecast through tomorrow: Storms have dissipated with some light to moderate showers remaining. That should mostly be the case through evening, then drier air works in overnight with lows in the 60s. Tomorrow turns partly sunny and breezy, with some gusts from the northwest near 30 mph, and highs probably only in the mid-to-upper 70s. Should feel nice!
6:00 p.m. update: With the line now pushing out of the immediate area and across the bay, the severe thunderstorm watch has been canceled in the D.C. area. Still, some light rain with occasional lightning is possible behind the batch, and another healthier (not severe) storm is pushing east along the Loudoun/Montgomery line. The bulk of the remaining activity should wind down over the next hour or two.
5:45 p.m. update: The heaviest of activity, all sub severe, is now pushing toward the bay. Calvert, Anne Arundel and Charles counties in particular are seeing some heavy rain as well as abundant thunder/lightning. Lighter rain with occasional thunder and lightning continues across a good part of the area behind the storms, with a few additional popups out in Loudoun County. The severe threat should be over across the area, though the watch has not been dropped yet.
5:30 p.m. update: Power outages as of the current time are almost 19,000 for Pepco with the vast majority (over 16,000) in Montgomery County. Dominion Power reports just over 1,000 outages in Northern Virginia with the majority in Loudoun, Fairfax and Prince William counties. See this interactive chart for tracking power outages.
5:20 p.m. update: The worst of the strong, but currently not severe, storms have now moved mainly east of D.C. and I-95 and will continue tracking east toward the Bay through Prince George’s and Anne Arundel counties and Southern Maryland over the next hour or two. Still, beware of a few more storms (probably weaker) to come through the area behind the main line over the next few hours.
4:55 p.m. update: Aside from some reports of downed trees in southern Rockville and north Potomac earlier, storms have remained sub-severe. Still, it’s turned dark as night as the storms move into downtown and a period of quite turbulent (wind/rain/lightning) weather accompanies their passage. Temps drop markedly as the storms pass through…up to 20 degs.
4:35 p.m. update: Very heavy storm presently moving through heart of metro area. Radar shows gusty but not damaging winds, and wall of heavy rain coming through. Frequent lightning is also accompanying these storms.
4:20 p.m. update: The heavy storms in Montgomery and Fairfax county are joining up, and a severe thunderstorm warning now covers the entirety of the immediate metro region, thru 5 p.m.
A few damaging wind gusts are possible as this comes through, but – mostly – people will experience heavy rain, some lightning, and general gustiness. A few instances of small hail are also possible.
4:00 p.m. update: The worst of the winds in the Montgomery county storms have pulsed down, but the storm is still likely producing some strong gusts, not to mention very heavy rain. We have also received reports of small hail with the cell. The worst of it is now moving into the Wheaton area.
Separately, a new severe thunderstorm warning has been issued for southern Fairfax and eastern Prince William counties until 4:45 p.m. A heavy storm extends from southern Fairfax, through Centreville and into Manassas and is headed due east around 20 mph.
3:50 p.m. update: A severe thunderstorm warning has been issued for eastern Montgomery, northern Prince George’s, and southern Howard counties until 4:30 p.m. Radar indicates a very intense cell with wind gusts which may easily exceed 50 mph around north Potomac and Bethesda. Seek shelter in this area.
3:45 p.m. update: Lightning may have struck the control tower at BWI Airport, and all flights are grounded. More information at Dr. Gridlock: BWI grounds flights due to lightning
3:35 p.m. update: Scattered storms, some locally quite heavy, are sprinkled across Montgomery, Loudoun, Prince William, and Fauquier counties. A severe thunderstorm warning covers north central Loudoun County and central Fauquier and western Prince William counties until 4:00 p.m. The main threat with any storm is damaging winds, but also be on alert for lightning, small hail and very heavy rain.
Storm and damage pictures
— Erik Russell (@Erik45EDT) September 12, 2013
— Richard Barnhill (@wolfpackwx) September 12, 2013
— Lacy Walker (@lacyluu) September 12, 2013
— Katy (@kdawg0128) September 12, 2013
Overview (3:07 p.m.): The National Weather Service Storm Prediction Center has issued a severe thunderstorm watch for the D.C. metro region until 10 p.m. tonight.
A strong cold front will move through the region and thunderstorm activity has already developed over the region. Storms, thus far, have not reached severe levels.
A widespread severe thunderstorm outbreak is not likely, but isolated instances of damaging winds (60-70 mph) and large hail (1″ in diameter) are possible.
SPC says there is a 30 percent chance of at least 10 reports of damaging winds in the watch area, which extends into eastern Pennsylvania and central New Jersey. Likewise, there is 30 percent chance of at least 10 large hail reports this rather large zone.
Stay tuned to the Capital Weather Gang for additional updates.