Flash flood watch through 10 p.m. for Montgomery, Prince George’s, Anne Arundel, and Howard counties
7:55 p.m. Update: A solid line of storms, part of which is producing torrential rainfall of more than 1 inch per hour, stretches from central Fairfax County east through DC/Arlington/Alexandria and central P.G. County, and continuing east through southern Anne Arundel County and across the Chesapeake Bay. The line, slowly drifting south and east, has prompted Flash Flood Warnings that are shown in the map below. Follow live updates on our Twitter feed above, and never drive across a flooded road.
From 4:15 p.m.: Today was pretty typical for mid-to-late August. Highs reached the mid-to-upper 80s with moderately high humidity. Whereas thunderstorms overachieved yesterday in their coverage and intensity, early returns suggest they’ll underachieve today. As for the weekend, Saturday looks dry and warm for the most part whereas thunderstorm chances increase Sunday.
Through Tonight: I’ll call for a 30 percent chance of showers and thunderstorms. Any that do develop may be slow moving, and thus capable of producing heavy rain. In addition, small hail and gusty winds may accompany storms. Storms have been slow getting going, but may develop/move in more between 5 and 10 p.m. before winding down. Later tonight, skies are partly cloudy with lows in the low 60s in the cooler suburbs to near 70 downtown.
Saturday and Sunday: Although an isolated storm can’t be ruled out (10-20 percent chance) in the afternoon or evening, Saturday is the drier of the two days. Skies are partly to mostly sunny with highs in the upper 80s to around 90. Mild Saturday night with lows in the mid-60s to low 70s (downtown). Sunday sees building afternoon clouds and 30-40% chance of afternoon and evening storms. Highs should be around 90. Both days are fairly humid.
Pollen update from Walter Reed: “When it rains it spores.....our mold spore count is in the HIGH range 35297.15 grains/cubic meter. Grass pollen is LOW at 0.64 gr/cubic meter, tree pollen is LOW at 0.32 gr/cubic meter and weed pollen is LOW at 2.88 gr/cubic meter.”
Hottest summer on record to date: The National Weather Service in Sterling wrote in its discussion this morning:
IT IS INTERESTING TO NOTE THAT FOR THE PERIOD JUN 1-AUG 17 AT REAGAN NATIONAL THIS IS THE WARMEST SUMMER ON RECORD...A RECORD THAT WAS SET JUST LAST YR. FOR MAX TEMPS THIS YEAR IS 90.8 VS 90.6 LAST SUMMER. AVERAGE TEMP THIS YEAR 81.8 VS. 81.7 IN 2010.