Severe Thunderstorm Watch, Flash Flood Watch Issued For NoVA, DC

WASHINGTON, DC — Slow-moving thunderstorms will roll across the Washington, D.C., region, on Tuesday, dumping several inches of rain and increasing the chance of flooding, forecasters say. Both a severe thunderstorm watch and a flash flood watch have been issued for The District of Columbia and parts of northern Virginia by the National Weather Service from 2 p.m. on June 17 until late Tuesday evening.

"A stalled front and a passing disturbance, combined with a tropical air mass, will result in a risk of severe storms and flooding rains today (Monday). A slight risk of severe weather exists across much of the region, and flash flood watches are also in effect," the weather service said.

At 2:10 p.m. Tuesday the agency issued a severe thunderstorm watch in effect until 10 p.m. for these areas: Arlington, Fairfax, Fauquier, Loudoun, Prince William, Stafford, Alexandria, Falls Church, Fredericksburg, Manassas, Manassas Park, Chantilly, Herndon, Leesburg, McLean, Reston, Sterling, Warrenton and Woodbridge, along with Washington, D.C.

The watch means that there is potential for severe thunderstorms. For the National Weather Service to consider a thunderstorm severe, it must produce winds of at least 58 mph and/or hail at least 1 inch in diameter.

These parts of Virginia are under the flash flood watch Tuesday: Arlington, Falls Church, Alexandria, Loudoun, Fairfax, Fauquier, Prince William, Manassas, Manassas Park, Stafford, Dale City, Woodbridge, Reston, Herndon, Annandale, Centreville, Chantilly, McLean, Franconia, Purcellville, Leesburg, Ashburn, and Sterling. Washington, D.C., and much of Maryland are also under the watch.

Thunderstorms with heavy rainfall are expected to develop across the watch area this afternoon and linger into the evening. Localized rainfall totals of several inches are possible. This
could lead to flash flooding, especially in the urban areas, the National Weather Service says.

A flash flood watch means that conditions may develop that lead to flash flooding. Flash flooding is a very dangerous situation, forecasters say, so residents should monitor later forecasts and be prepared to take action if flash flood warnings are issued.

"A very warm, humid weather pattern has replaced the refreshing conditions late last week. This mugginess fuels storms firing up along a cold front near the region for the first few days this week, especially in the afternoon and evening hours," writes The Washington Post's Capital Weather Gang. "Some of these storms could be heavy with strong winds and possibly some flooding. The front should finally clear the region late Thursday, setting up a nice Friday and Saturday."

Here's a look at this week's forecast, from the National Weather Service:

Tuesday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2pm. Some of the storms could produce heavy rain. Patchy fog before 11am. Otherwise, cloudy, with a high near 87. West wind 5 to 7 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Tuesday Night: Showers likely and possibly a thunderstorm. Some of the storms could produce heavy rain. Cloudy, with a low around 69. South wind 3 to 7 mph. Chance of precipitation is 70%. New rainfall amounts between a quarter and half of an inch possible.

Wednesday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2pm. Patchy fog before 11am. Otherwise, cloudy, with a high near 85. South wind 3 to 6 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Wednesday Night: Showers and thunderstorms likely before 2am, then a slight chance of showers between 2am and 5am. Mostly cloudy, with a low around 70. South wind around 5 mph becoming calm after midnight. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Thursday: A chance of showers and thunderstorms between 8am and 2pm, then showers likely and possibly a thunderstorm after 2pm. Mostly cloudy, with a high near 90. Calm wind becoming southwest 5 to 8 mph in the morning. Chance of precipitation is 60%.

Thursday Night: Showers likely and possibly a thunderstorm before 8pm, then a chance of showers and thunderstorms after 8pm. Mostly cloudy, with a low around 68. Chance of precipitation is 60%.

Friday: Mostly sunny, with a high near 82.

Friday Night: Mostly clear, with a low around 63.

Saturday: Mostly sunny, with a high near 83.

Saturday Night: Mostly cloudy, with a low around 66.

Sunday: Partly sunny, with a high near 86.