* WHAT. South winds 10 to 15 kt expected with gusts up to 20 kt expected. * WHERE. Chesapeake Bay north of Sandy Point MD, Patapsco River including Baltimore Harbor, and Chester River to Queenstown MD. * WHEN. Until noon EDT Thursday. * IMPACTS. Conditions will be hazardous to small craft.

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

SMWLWX The National Weather Service in Sterling Virginia has issued a * Special Marine Warning for. Chesapeake Bay from Pooles Island to Sandy Point MD. Chesapeake Bay north of Pooles Island MD. * Until 800 PM EDT. * At 657 PM EDT, severe thunderstorms capable of producing waterspouts were located along a line extending from 6 nm north of Middle River to Pooles Island to 6 nm east of Tolchester Beach, moving northeast at 40 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. Turkey Point, Gunpowder River, Northeast River, Tolchester Beach, Worton Point, Pooles Island, Spesutie Island, Aberdeen Proving Ground, Havre De Grace, and Middle River.

TORLWX The National Weather Service in Sterling Virginia has issued a * Tornado Warning for. Northwestern Montgomery County in central Maryland. Southeastern Frederick County in north central Maryland. Northeastern Loudoun County in northern Virginia. * Until 730 PM EDT. * At 652 PM EDT, severe thunderstorms capable of producing brief tornadoes were located along a line extending from 6 miles east of Point Of Rocks to near Poolesville to Leesburg, moving east at 20 mph. HAZARD. Tornado. SOURCE. Radar indicated rotation. IMPACT. For those in the direct path of a tornado touchdown, flying debris will be dangerous to those caught without shelter. Damage to roofs, siding, and windows may occur. Mobile homes may be damaged or destroyed. Tree damage is likely. * These dangerous storms will be near. Leesburg, Lansdowne, and Poolesville around 700 PM EDT. Boyds around 705 PM EDT. Germantown and Damascus around 710 PM EDT. Other locations impacted by these tornadic storms include Clarksburg, Dickerson, Beallsville, Dawsonville, Tuscarora, Barnesville, and Darnestown.

TORLWX The National Weather Service in Sterling Virginia has issued a * Tornado Warning for. East central Frederick County in north central Maryland. * Until 730 PM EDT. * At 700 PM EDT, a severe thunderstorm capable of producing a tornado was located near Walkersville, or near Frederick, moving northeast at 20 mph. HAZARD. Tornado. SOURCE. Radar indicated rotation. IMPACT. For those in the direct path of a tornado touchdown, flying debris will be dangerous to those caught without shelter. Damage to roofs, siding, and windows may occur. Mobile homes may be damaged or destroyed. Tree damage is likely. * This tornadic thunderstorm will remain over mainly rural areas of east central Frederick County in north central Maryland, including the following locations. Libertytown and Unionville.

At 701 PM EDT, severe thunderstorms capable of producing tornadoes were located along a line extending from 6 miles northwest of Boyds to near Poolesville to near Lansdowne, moving east at 20 mph. HAZARD. Tornado. SOURCE. Radar indicated rotation. IMPACT. For those in the direct path of a tornado touchdown, flying debris will be dangerous to those caught without shelter. Damage to roofs, siding, and windows may occur. Mobile homes may be damaged or destroyed. Tree damage is likely. These dangerous storms will be near. Poolesville and Boyds around 705 PM EDT. Germantown and Damascus around 710 PM EDT. Other locations impacted by these tornadic storms include Dawsonville, Clarksburg, Dickerson, Barnesville, Beallsville, and Darnestown.

At 705 PM EDT, a severe thunderstorm capable of producing a tornado was located near Walkersville, or 8 miles northeast of Frederick, moving northeast at 20 mph. HAZARD. Tornado. SOURCE. Radar indicated rotation. IMPACT. For those in the direct path of a tornado touchdown, flying debris will be dangerous to those caught without shelter. Damage to roofs, siding, and windows may occur. Mobile homes may be damaged or destroyed. Tree damage is likely. Locations impacted include. Libertytown and Unionville.

At 709 PM EDT, tornado producing storms were located along a line extending from 6 miles north of Boyds to near Poolesville, moving east at 20 mph. HAZARD. Damaging tornado. SOURCE. Radar confirmed tornado. IMPACT. For those in the direct path of a tornado touchdown, flying debris will be dangerous to those caught without shelter. Damage to roofs, siding, and windows may occur. Mobile homes may be damaged or destroyed. Tree damage is likely. These tornadic storms will be near. Germantown, Damascus, Poolesville, and Boyds around 715 PM EDT. Other locations impacted by these tornadic storms include Dawsonville, Clarksburg, Barnesville, Beallsville, and Darnestown.