Most Read: Local

Posted at 05:00 PM ET, 05/18/2011

PM Update: Shower/t’storm chances roll on

* Flash Flood Watch for entire area through evening for possible rainfall rates of 1-2” during showers/storms; Flood Warning for Potomac River near Little Falls (affecting Montgomery & Fairfax counties); Coastal Flood Warning for D.C., Alexandria and western shore of Chesapeake Bay until 2 p.m. Thursday; Coastal Flood Advisory for remainder of tidal Potomac until 2 a.m. Thurs. (and Coastal Flood Watch thereafter) *

9:55 p.m. update: Showers and storms have weakened and are now lifting through the northern suburbs. Widely scattered showers/storms remain possible overnight, but should not be severe. Be sure to see some of the videos and photos below. The hail in Leesburg was pretty remarkable.

8:30 p.m. update: The Severe Thunderstorm Watch has now been canceled for the area. Despite the substantial weakening, still watch out for gusty showers with a bit of lightning and a touch of hail possible. The precipitation is moving north through the metro area, stretching west to east from around eastern Loudoun County through the District, and now entering southern Montgomery County.

Storm videos and photos:

Video of hail from Fredericksburg (via Twitter from macaroni_mac).

Hail video from Leesburg (courtesy Leanne Littman)

Marble-sized hail in Leesburg | Hail covering ground in Leesburg (from @shahrum via Twitter)

More hail from Leesburg from @kalcaloya

Cool clouds from: Southwest DC (from@TweetJeanster) and Judiciary Square in DC (from @laduper)

Overview from 3:30 p.m.: We’ve been treated the daily shower and thunderstorm threat yet again , this time impacting parts of the immediate D.C. area at an earlier midday hour than recently. The risk continues, with a Severe Thunderstorm Watch in effect until 9:00 p.m. across the region, and recent tornado warnings east of the bay and north of Baltimore as well as severe storm warnings in Loudoun. Even with minimal daytime warmth, and highs right around 70, we’ve seen just enough sunshine to keep things percolating.

Through Tonight: Showers and t‘storms should remain isolated to scattered for the rest of the afternoon and pushing through the evening. However, any storm that strengthens enough could produce severe weather including damaging winds, hail, and perhaps even a tornado — not to mention heavy rain and lightning. Be sure to keep a watch on radar and the sky if heading out! The severe risk should dwindle after sunset, though isolated showers remain possible through the night as lows reach the upper 50s to near 60.

Severe Weather Tracking Station
Warning Text: DC | MD | VA * NWS Local Storm Reports
Radar & Lightning: Movement of precipitation and lightning strikes over past two hours. Refresh page to update. Click here to see radar bigger.
    
LWX Warnings
Warnings: Severe alerts from National Weather Service. Updates w/o refresh (most browsers). Hint: Alert on map? Click matching label in key for details.

Tomorrow (Thursday): The pesky upper-level low pressure system continues to only slowly move northeastward, so we’re under its grip yet again. As has been the story of late, showers and thunderstorms are possible throughout the day, but the best odds are probably in the afternoon. Any showers or storms should produce briefly heavy rain, some lightning, and perhaps isolated severe weather. Highs reach the low-to-mid 70s.

See Dan Stillman’s forecast through the weekend. And if you haven’t already, join us on Facebook and follow us on Twitter .

Big western snows: Even though we’re only a short distance off of summer, snow continues to fall in the intermountain west. Over the last several days, Squaw Valley, California has recorded about 2’ of new snow, bringing their seasonal total past 760”, a new record for them. Many mountains except those in Arizona and New Mexico, have received 150% to 200%+ normal snowfall this season. You can take a look at current depths here.

Pollen update: Recent rains have alleviated some pollen issues, at least temporarily. Grass pollen is LOW (moderate for this area) at 3.83 grains/cubic meter, tree pollen is MODERATE at 79.87 grains/cubic meter, weed pollen is LOW at 1.92 grains/cubic meter and mold spores are in the MODERATE range with 7,797.31 grains/cubic meter.

Keep reading for earlier storm updates...

Earlier (now out of date) storm updates:

8:15 p.m. update: Showers and storms weakening now as they move north into and through Fairfax County, D.C. and eastern Loudoun County. Lightning activity has dwindled but still a few strikes possible (so head indoors if you hear thunder roar). Winds and hail potential probably diminishing too but a strong gust or a bit of small hail possible. Probably not like this earlier video of hail from Fredericksburg (via Twitter from macaroni_mac).

7:40 p.m. update: Strong storm moving north through southeast Prince William, northern Charles and northern Stafford counties now. Should move into southern Fairfax County in the next 30 minutes. Wind gusts to 40-50 mph and small hail are possible along with heavy rain and lightning. This is the storm that had a severe warning on it before but has weakened slightly. Right now no Severe T’storm Warnings in effect in area.

6:50 p.m. update: Large area of rain and embedded thunderstorms, some severe (see 6:45 p.m. update below), is clustering to the south just east of I-95 from central Spotsylvania and Stafford counties to St. Mary’s county. This activity is moving due north and should arrive in the southern part of the metro area around 8 p.m.

6:45 p.m. update: Severe thunderstorm warning for Fredericksburg, and much of Stafford, southeast Fauquier, and southwest Prince William county until 7:30 p.m. Gusty winds and hail are possible with this storm. Storm over Charles county has weakened but still may graze southeast Fairfax county and western Prince George’s county as it moves northward..

6:00 p.m. update: Severe thunderstorm warning for western Charles, northeast Stafford, and eastern Prince William county until 6:45 p.m. Storm has a history of large hail to 1” in diameter (half dollar size). Damaging winds are also possible with these storms moving north at 15 mph. In path: Indian Head and Woodbridge. Storm may reach southern Fairfax county by around 7 p.m.

5:20 p.m. update: Severe thunderstorm warning for eastern Stafford & western Charles county until 6 PM. Torrential rain, hail & strong winds possible. Storm in Stafford has already produced penny size hail. The D.C. metro region needs to watch this area of storms as it moves north northeast at about 20 mph. If it holds together, could move into close-in suburbs between 6 and 7 p.m.

4:45 and 5:00 p.m. update: The severe thunderstorm and tornado warnings have expired across the area but heavy rain and the potential for flash flooding persists in northwest Loudoun county. Otherwise, radar shows little in the D.C. metro region, but we will watch some developing storms moving north in southern Stafford and Fauquier counties which could become severe and/or produce more flash flooding.

4:15 p.m. update: Twitter followers (and Facebook) from Brambleton, Va. (Loudoun co.) to Brunswick, Md. (southwest Frederick co) reporting “epic” hail and torrential rain from storm. Meanwhile, a tornado warning is in effect (for the second time today) in eastern Baltimore and western Harford counties through 4:45 p.m. Doppler radar indicated a possible tornado near Middle River moving northwest at 25 mph.

4:00 p.m. update: While thunderstorm activity continues to elude metro D.C., central through northwest Loudoun county is under a severe thunderstorm warning until 4:30 p.m. Torrential rain (a flash flood warning is also in effect there), hail and winds to 60 mph. The storm is moving northwest at 25 mph.

By , and  |  05:00 PM ET, 05/18/2011

Categories:  Forecasts

 
Read what others are saying
     

    © 2011 The Washington Post Company