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Posted at 03:45 PM ET, 08/18/2011

PM Update: Heavy thunderstorms in parts of region; more possible Friday

9:30 UPDATE: Showers and storms continue to be scattered about the region. The heaviest of activity has set up west and southwest of D.C., with radar estimates of as much as 4” of rain near Centreville, Va. Activity should continue to wind down, but storms may persist for some time yet and places to the east could still get in on more action. Numerous reports of small hail have been coming in from Loudoun County in particular.

7:30 UPDATE: Some very heavy rain totals mounting between Gainesville and Centreville (lookout for isolated flooding) where storm has essentially stalled. A piece of the storm has moved to the northeast just north of Fairfax but is no longer severe. As long as it holds together it showed continue northeast through southern Montgomery county over next hour. But in general, by 9 p.m., activity should be winding down. We’ll update again if needed.

Also, Severe Thunderstorm Warning issued for extreme northeast Anne Arundel county and southeastern Baltimore county through 8:15 p.m. Storm likely to produce small hail and possibly damaging winds before moving away.

7:20 UPDATE: Severe thunderstorm warning for extreme northeast Prince William and much of western and central Fairfax county through 8 p.m. Storm likely to produce hail and may produce strong winds. Hail reported in Chantilly.

5:50 UPDATE: Flash Flood warning for northern Fairfax and southern Montgomery county until 8:45 p.m., including Fairfax City - and for northern Anne Arundel county until 8 p.m. A train of thunderstorms has formed from eastern Loudoun county through north central Fairfax county. All of this activity, containing torrential rain and some hail, is slowly moving east towards northeast Fairfax county (mainly north of I-66), the northern half D.C. and southern Montgomery county. Allow extra time for your commute and do not attempt to drive through flooded roads. Turn around, don’t drown.

A muggy, sometimes smoky day (with highs near 90) has transitioned into one with scattered coverage of showers and thunderstorms - some with heavy downpours, strong winds, and hail. Those gradually wind down after dark. After a mild overnight, we see a similar sequence of weather events during the day Friday.

Through Tonight: About 30-40% of us see showers and thundershowers this evening. This activity should diminish and/or exit after sunset. For the remainder of the night, it’s partly cloudy with lows from the mid-60s in the cooler suburbs to the low 70s downtown.

Tomorrow (Friday): Expect almost a carbon copy of today. We’ll see sun at times, but building cumulus during the afternoon as thundershowers develop - with about 40% of us being impacted through evening. It’s fairly humid, with highs in the upper 80s to near 90.

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

Pollen update from Walter Reed:“Grass pollen is LOW at 1.5 gr/cubic meter, weed pollen is LOW (NAB range) at 5.11 gr/cubic meter, which for our local area is more moderate. Mold spores are in the MODERATE range at 11,848.54 spores/cubic meter.”

Earlier severe weather updates

5:20 UPDATE: Severe thunderstorm warning for central and northeast Fairfax county, southern Montgomery county, and northwest D.C. through 6 p.m. Small to moderate-size (0.75-1”) hail has been reported in Fairfax - enough to cover the ground. Storm may also produce strong winds to 60 mph.

6:00 UPDATE: Severe thunderstorm warning for northern half of Fairfax county, southern Montgomery county and northern half of DC thru 6:45. Flooding rain, damaging winds & hail possible. Major hailstorm reported in Herndon. Traffic at standstill at Dulles Access Road and I-66W. Delay commute if possible in northern Fairfax county

6 :25 UPDATE: Severe thunderstorm warning for eastern Montgomery, northern Prince George’s and extreme southern Howard county through 7 p.m. Widespread reports of hail to the size of quarters reported around Wheaton and Glenmont.

6:50 UPDATE: Severe thunderstorm warning for southeast Howard, northern Anne Arundel, northern Prince George’s and Baltimore counties through 7:30 p.m. Storm capable of producing flooding rain, hail to quarter-size and winds to 60 mph moving northeast.

To the west, we are watching two other storms. They are impacting the I-270 corridor in Montgomery county as well as northern Prince William into extreme western Fairfax county (moving towards Centreville and Chantilly). Small hail cannot be ruled out with these storms. Over the next hour, storms should begin decreasing in coverage and intensity.

6:40 UPDATE: Confirmed reports of hail as large as golf balls in Wheaton. Hail producing storm moving in direction of Laurel.

By  |  03:45 PM ET, 08/18/2011

Categories:  Forecasts

 
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