...FLOOD WATCH IN EFFECT UNTIL 8 PM EDT THIS EVENING... * WHAT...Flash flooding caused by excessive rainfall is possible. * WHERE...Portions of DC, Maryland, and northern Virginia, including the following areas: in DC, District of Columbia. In Maryland, Anne Arundel, Carroll, Central and Southeast Howard, Central and Southeast Montgomery, Charles, Frederick MD, Northern Baltimore, Northwest Harford, Northwest Howard, Northwest Montgomery, Prince Georges, Southeast Harford, and Southern Baltimore. In northern Virginia, Arlington/Falls Church/Alexandria, Central and Southeast Prince William/Manassas/Manassas Park, Eastern Loudoun, Fairfax, Northwest Prince William, Stafford and Western Loudoun. * WHEN...Until 8 PM EDT this evening. * IMPACTS...Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. * ADDITIONAL DETAILS... - A couple rounds of slow-moving showers and thunderstorms are likely this afternoon into this evening. A few inches of rain is possible in a short amount of time as a result, and may cause rapid rises of water on creeks, streams, urban and poor drainage areas, and in other flood-prone locations. - Please visit weather.gov/safety/flood for flood safety and preparedness information. PRECAUTIONARY/PREPAREDNESS ACTIONS... You should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. By The National Weather Service, Sterling, Va.