With rain clouds hovering over the area, a flash flood watch is in effect for most of the D.C. region, and several crashes have been reported on rain-slickened roads.
The National Weather Service has also issued a flood warning for D.C., parts of Montgomery County and Prince George’s County in Maryland and Arlington County, Fairfax County, Alexandria, Fairfax and Falls Church in Virginia until 5 a.m.
A similar warning is also in effect in Virginia for most of Culpeper, Fauquier and Prince William Counties and Manassas and Manassas Park until 4:30 a.m. and for most of Calvert and St. Mary’s Counties in Maryland until 3:45 a.m.
The flash flood watch from the National Weather Service remains in effect until Thursday 11 a.m. The weather service says to expect several rounds of moderate to heavy rainfall with a few possible embedded thunderstorms.
A total rainfall of 2 to 4 inches is expected through Thursday, according to the watch.
The deluge of rain comes courtesy of a surge of tropical moisture, which has brought incredibly humid air into the region, according to NBC Washington meteorologist Chuck Bell.
Slippery roads led to some crashes Wednesday that snarled traffic on some key roads.
An overturned tractor-trailer on Interstate 270 in Hyattstown, Maryland, Wednesday afternoon blocked the northbound lanes of the interstate between Hyattstown and Urbana, leading to severe delays.
Old Courthouse Road at Besley Road in Vienna, Virginia, was closed Wednesday evening due to flooding.
— Fairfax County Police (@FairfaxCountyPD) November 11, 2020
Earlier Wednesday, a crash on northbound Baltimore-Washington Parkway near Greenbelt, Maryland, slowed traffic for several hours.
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Looking ahead, a brief lull in the steadiest rain is likely Wednesday afternoon, the weather service said Temperatures are expected to rise after sunset and hover around 70 degrees before the heaviest rain is expected to move in between sunset Wednesday and sunrise on Thursday.
Multiple rounds of rain are expected today into Thu morning as deep moisture interacts with a slow moving cold front. One to up to 4 inches of rain are expected, heaviest along & east of I-95 corridor, which may result in scattered incidents of flooding. #DCwx #MDwx #VAwx #WVwx pic.twitter.com/rj8tPawvrf
— NWS Baltimore-Washington (@NWS_BaltWash) November 11, 2020
Rainfall totals are expected to range from about an inch over western Maryland to 2-3 inches across Northern Virginia, southern Maryland and the D.C. metro area.
The rain will taper to showers on Thursday morning and end around sunset.
Because the local area has been “fairly dry” over the last 10 days, the risk of major flooding is low. But, Bell said that the high rainfall rates make the risk of urban flooding high.
Drivers are urged to take extreme caution if driving overnight Wednesday or Thursday morning as many roads are likely to have high or standing water on them.
Cooler weather is expected this weekend, with some light showers possible on Friday.
Wednesday: Rain, moderate at times continuing overnight. Highs: upper 60s to low 70s.
Wednesday night: Heavy rain with 1 to 3 inches possible. Highs: mid 60s to low 70s.
Thursday: Steady rain during the first half of the day. Cloudy and cooler. Highs: upper 50s.
Friday: Cooler, sunny and seasonable. Highs: mid 50s to high 60s.
Saturday: Seasonably chilly with high clouds. Highs: mid to upper 50s.