SMWLWX The National Weather Service in Sterling Virginia has issued a * Special Marine Warning for. Tidal Potomac from Indian Head to Cobb Island MD. Tidal Potomac from Key Bridge to Indian Head MD. * Until 400 PM EDT. * At 255 PM EDT, a severe thunderstorm capable of producing waterspouts was located over Gunston Hall, moving northeast at 20 knots. HAZARD. Wind gusts 34 knots or greater, waterspouts, and small hail. SOURCE. Radar indicated. IMPACT. Boaters in small craft could be thrown overboard by suddenly higher winds and waves capsizing their vessel. Waterspouts can easily overturn boats and create locally hazardous seas. * Locations impacted include. Fort Washington, Tidal Basin, Reagan National Airport, Gunston Hall, Woodrow Wilson Bridge, Key Bridge, Fort Hunt, National Harbor, and Alexandria.

A warm front accompanied by showers and a few thunderstorms will result in a brief period of wind gusts of 20 to 25 knots. Mariners should exercise extra caution if navigating the waters during this time.

A cluster of showers and thunderstorms will crawl along the Maryland border through 6 PM. The area between the Turnpike and the Maryland line is the most likely to see short periods of torrential rain. The rain could be intense at times, with rainfall rates near 2 inches per hour. Rainfall rates like this could lead to minor flooding, especially in urban areas.

* WHAT. Flash flooding caused by excessive rainfall continues to be possible. * WHERE. Portions of DC, including the following , District of Columbia, Maryland, including the following areas, Anne Arundel, Central and Southeast Howard, Central and Southeast Montgomery, Northwest Howard, Northwest Montgomery, Prince Georges and Southern Baltimore, and northern Virginia, including the following areas, Arlington/Falls Church/Alexandria, Central and Southeast Prince William/Manassas/Manassas Park, Eastern Loudoun, Fairfax and Northwest Prince William. * WHEN. Until 10 PM EDT this evening. * IMPACTS. Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. Flooding may occur in poor drainage and urban areas. Low-water crossings may be flooded. * ADDITIONAL DETAILS. - Multiple rounds of heavy showers and thunderstorms will move across the area today into this evening. Rainfall amounts of 1 to 2 inches are likely, with isolated amounts of 3 to 4 inches possible. - Please visit www.weather.gov/safety/flood for flood safety and preparedness information