The National Weather Service has issued a Flash Flood Watch for the entire Northern Virginia area, including Alexandria, Arlington, Fairfax County and Falls Church.
The watch is in effect until midnight Thursday night.
The weather service notes that slow-moving showers and thunderstorms are likely through this evening; locally heavy rainfall is expected in excess of 2 inches per hour. In targeted areas that receive heavy downpours for longer than 30 minutes, flash flooding may begin quickly, the NWS warns.
Residents should also be aware of low areas that may flood; the NWS warns drivers to "turn around, don't drown."
A Flash Flood Watch means that conditions may develop that lead to flash flooding; monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued, the service notes.