SMWLWX The National Weather Service in Sterling Virginia has issued a * Special Marine Warning for. Tidal Potomac from Key Bridge to Indian Head MD. * Until 945 PM EDT. * At 822 PM EDT, a severe thunderstorm capable of producing waterspouts was located over Alexandria, moving east at 10 knots. HAZARD. Wind gusts 34 knots or greater and waterspouts. 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, Woodrow Wilson Bridge, Key Bridge, Fort Hunt, National Harbor, and Alexandria.