(originally posted at 3:50 a.m., updated through 9:50 a.m.)
9:50 a.m. Update: Tornado warning for PG and Charles counties canceled.
9:30 a.m. Update: Tornado warning in effect for southern Prince George's and north central Charles county until 10 a.m. NWS indicates doppler radar indicated tornado near Waldorf moving northeast at 45 mph. Locations in possible path include Clinton. Take cover if you live in that area.
9:10 a.m. Update: Heavy showers and storms, with 50+ mph wind gust potential, are impacting eastern Fairfax and Montgomery counties. This activity will push east and northeast toward the District and western Prince George's county in the next 30-45 minutes. Further north A Severe Thunderstorm Warning is in effect for Howard and Baltimore counties (until 10:15 a.m.) where 60+ mph wind gusts are possible.
Keep reading for earlier updates and information about the Tornado Watch...
8:10 a.m. Update: A line of strong storms moving west to east across the far northern suburbs has prompted a Severe Thunderstorm Warning until 8:45 a.m. for northern Montgomery County, northern Howard County and eastern Frederick County. As with storms earlier this morning, winds gusts to near 60 mph are a threat. Montgomery Village and Damascus are among the locations that could see these storms.
6:20 a.m. Update: The line of heavy rain and strong wind that had been approaching and moving into western and northwestern suburbs has weakened. So at the moment, no Severe Thunderstorm Warnings are in effect in the metro area. However, the entire metro area remains under the gun for moderate to heavy rains (rain rates up to 1" per hour) through the morning commute and the potential for wind gusts of 50-60 mph+ that could bring down trees and cause power outages.
5:50 a.m. Update: The line of heaviest rain and strongest winds is now entering eastern Loudoun County, and in the next 45 minutes or so may clip northwestern Fairfax County and reach into Montgomery and Frederick counties. These areas are under a Severe Thunderstorm Warning until 6:30 a.m. The entire metro area remains under the gun for moderate to heavy rains (rain rates up to 1" per hour) through the morning commute and the potential for wind gusts of 50-60 mph+ that could bring down trees and cause power outages.
5:15 a.m. Update: Severe Thunderstorm Warnings are in effect until 5:45 a.m. for most of Fauquier (also under a Flash Flood Warning) and Stafford counties, southern Loudoun County, the western half of Prince William County, and the western fringe of Fairfax County. While there doesn't seem to be much lightning with these storms, the winds are the real concern, with gusts in excess of 60 mph possible according to NWS. These warnings, winds and heavy rain are likely to advance east through the metro area over the next couple hours.
4:50 a.m. Update: Moderate to heavy rain is now falling in Loudoun and Fauquier counties, the latter of which is under a Flash Flood Warning until 10:30 a.m. NWS warns, "IN HILLY TERRAIN THERE ARE HUNDREDS OF LOW WATER CROSSINGS WHICH ARE POTENTIALLY DANGEROUS IN HEAVY RAIN. DO NOT ATTEMPT TO TRAVEL ACROSS FLOODED ROADS."
From 3:50 a.m.: The National Weather Service's Storm Prediction Center (SPC) has issued a Tornado Watch until 10 a.m. for the entire metro region. Specifically, the watch includes the following areas:
The District, central and southern Md., northern Va., far eastern West Va., and coastal waters.
SPC cautions: "Tornadoes...hail to 0.5 inch in diameter...thunderstorm wind gusts to 70 mph...and dangerous lightning are possible in these areas."
It notes: "Main severe threat will be isolated damaging wind from [straight line winds]...but a short-lived tornado or two cannot be ruled out."
Showers and thunderstorms, with heavy rain and the potential for these damaging winds, will push through the metro region between 4 a.m. and about 9 or 10 a.m. If a tornado warning is issued for your area, seek shelter in a basement or, if no basement, an interior room on the lowest level where you live.