Flash flood warning north; state of emergency in Md.

10:00 p.m. update: Light to moderate rain showers continue to work south to north through the region, but the back edge is getting close and the severe thunderstorm threat is pretty much done. With the cold front behind us now, temperatures have fallen back into the 40s and the rain should end over the next couple of hours. The flash flood warning over the District has now been discontinued but river flood warnings remain in effect. Remember never cross standing water on roadways, especially at night when it is harder to judge depth.

The National Weather Service reports 12-20 trees were knocked in Centreville around 7:00 p.m. near Eleanor Lawrence Park and Walney Road on Rt. 28. It’s not clear if this was due to straight line winds or a tornado but presumably the National Weather Service will assess tomorrow.

8:10 p.m. update: All the severe thunderstorm (or earlier tornado) warnings have ended, and the risk of more is low. The main heavy rain threat moves north with what’s left of the line that passed through the area, though additional light to moderate showers are a good bet over the next few hours, probably ending around or just after midnight. On a wind shift to the west and northwest, temperatures fall through the 50s and 40s over the next few hours.

Some reports of wind damage are coming in across the area, particulary in Virginia. In addition, flash flood warnings continue through late evening in the immediate area and to the north.

7:35 p.m. update: The tornado warning that was in effect until 7:30 p.m. has ended. Showers and storms are now moving into the northern and eastern portions of the area while weakening at least a bit. The air mass north of D.C. is more stable than it was to the south, so the main severe storm risk is dwindling. However, heavy rain is accompanying this activity and it will only exacerbate any flooding problems. Remember, never drive into standing water on roadways. More showers are possible behind the line, but they will be lighter as cooler air starts moving in.

7:10 p.m. update: A severe thunderstorm warning has been issued for parts of Anne Arundel, Prince Georges, Fairfax, and surrounding areas until 8:00 p.m. These storms are capable of producing winds past 60 mph.

7:00 p.m. update: A TORNADO WARNING has been issued for west central Montgomery, eastern Loudoun, north central Prince William and northwestern Fairfax counties until 7:30 p.m. This storm was near Centreville and moving toward Dulles International, South Riding, Arcola, Broadlands, Herndon, Brambleton, Ashburn, Countryside, Lansdowne and Lowes Island. Take cover immediately in these areas.

6:45 p.m. update: The earlier tornado warning has ended, but some rotation continues in the storm near Manassas. Other warnings issued earlier remain in effect. Storms moving through central Fairfax county and crossing the Potomac river south should move into D.C. over the next half hour.

6:30 p.m. update: The severe thunderstorm watch has been extended north across the area.

6:20 p.m. update: A TORNADO WARNING has been issued for central Fauquier and northwestern Prince William county until 6:45 p.m. A storm capable of producing a tornado was near Bealeton, Va. and Warrenton, The Plains and Harmarket are in line. Take cover immediately in these locations.

6:15 p.m. update: A severe thunderstorm warning is now in effect for Fauquier, Loudoun, Prince William, Fairfax, Stafford and Charles counties as a line of severe thunderstorms moves north northeast through the area. Damaging winds in excess of 60 mph are possible.

6:05 p.m. update: A flash flood warning has been issued for most of the metro area until 9:45 p.m. as potentially dangerous thunderstorms move through the region. Watch out for ponding on roadways and sidewalks, and remember not to drive through standing water. A state of emergency has been declared in Maryland due to the flooding.

5:40 update: Another warning has been issued for Loudoun and parts of Fauquier county not covered by the previous one -- also for winds to 60 mph. It runs until 6:15 p.m. Storms will move toward D.C. over the next hour.

5:25 p.m. update: A severe thunderstorm warning is in effect for Fauquier and Stafford counties (as well as most surrounding counties) through 6 p.m. These storms are quickly headed northeast toward the area and the line looks pretty nasty. The warning notes that winds as high as 60 mph are possible. Flood warnings also continue in the region through late evening. Additionally, a state of emergency has been declared in Maryland due to the flooding.

4:25 p.m. update: Heavy rain that has dropped as much as .5” to 1” in the last hour and a half in spots near D.C. and to the east is now lifting north as flood warnings continue (now also covering Montgomery, Anne Arundel and Prince Georges counties) through late evening. Additional showers and thunderstorms (some now severe warned) to the south and southwest will move toward us, arriving around 6 p.m. across the southwest portion of the region. There may be a sizeable break in between these rounds, but spottier showers or additional development is possible prior to the next round.

3:00 p.m.: A flood warning has been issued for D.C., Arlington, Prince William, Fairfax and Stafford counties through 9 p.m. due to periods of rain moving through the area this afternoon, and that remains the case before things taper off overnight. Highs have crept into the mid-and-upper 50s as air flow from the south and southeast continues ahead of a cold front and low pressure system slated to pass by over the next several hours.

Through Tonight: More bands of rain (including a new slug moving north now) wander slowly across the area, and we’re keeping on eye on the severe thunderstorm risk as the cold front passes later. A <a href=”http://www.spc.noaa.gov/products/watch/ww0049.html”>thunderstorm watch remains in place to our south</a> and some of that activity could work it’s way up here, even though we remain in ‘cool’ and stable air just north of the warm front for now. Any storms may contain damaging winds and perhaps an isolated tornado. By late evening the rain threat should be dwindling, and after midnight the risk mostly disappears while drier plus slightly cooler air filters in from the northwest. Lows range from around 40 to the mid-40s.

Tomorrow (Friday): We finish the work week with a rather pleasant and near average day. Partly cloudy skies and a breeze from the northwest, sustained near 10 mph at times with gusts to around 25 mph, mix with highs in the low-to-mid 50s.

See David Streit’s forecast through the beginning of next week. And if you haven’t already, join us on Facebook and follow us on Twitter.

Rain and flooding: Rainfallnow ranging from about 0.75” (west) to 1.5” (east) -- some higher and lower -- continue to cause problems across the region. Some area schools even let out early today thanks to increasingly flooded roads. Dr. Gridlock reports that the American Legion MARC lot at the Laurel station will be closed through Friday due to river flooding. Further north, officials in the Baltimore area are also bracing for flooding, though no major incidents have been noted thus far.