Moderate to Monsoon: State of Emergency

Flash Flood Watch is in effect for the entire DC area until Wednesday morning

State of Emergency declared in Washington, DC

9pm update: Heaviest rain is west of the beltway where the highest rainfall totals are likely tonight. Generally 1-3" should fall across the area (with isolated higher amounts--especially west) with rainfall tapering off late tonight. Rain may be enhanced as tropical low moves northward for a time between about 10pm and 3am. Washington Post: More Rain Heading to Washington.

6:45 Update:Flash Flood Warnings have now been issued for most of the immediate DC metro area.

5:30 Update: The low pressure area in the Atlantic moved inland near Morehead City NC before it could develop. However, it is spreading heavy rains and gusty winds across the Outer Banks as it moves northward.

To follow the current storm progress in the Washington area, periodically refresh the radar image from wunderground.com.
For storm related links and a timeline through tomorrow, scroll down to Matt's earlier post below.

With the lower half of the atmosphere almost completely saturated, storms can break out just about anywhere in the region the rest of this afternoon and evening, and storms now in central Virginia will continue moving north or west of north toward the DC area. Although some downpours may be brief, they can also be quite heavy.

After 2.56" of rain fell at National Airport in the 24 hours ending this morning, by early this afternoon, only 0.02" fell, but a heavy shower has raised that by 0.21" in only 14 minutes in the past hour. In an almost complete reversal of the usual thunderstorm path in this area, that storm moved from Prince George's County across the District from Southeast to Northwest, and is now pushing into Montgomery County, where rain is ranging from moderate to monsoon outside the window of Afternoon Blog Central. The main focus of activity so far today, however, is somewhat to the west of the immediate metro area. The most widespread heavy storms extend from near Hagerstown to south of Charlottesville.

Another issue of concern is a weak low pressure area about 35 miles off the lower North Carolina coast. The National Hurricane Center reported this afternoon that a reconnaissance flight found some gale force winds in the eastern portion of the area, but there was no closed circulation; therefore, it is not a tropical cyclone, at least yet. It does have the potential to develop into a tropical storm, however. Depending on the exact track of this disturbance as it moves northward, it could inject even more moisture into the DC region, or it could remain closer to the coast. In any case, the models are predicting several more inches of rain through the next day or so.