* WHAT. Flash flooding caused by excessive rainfall is possible. * WHERE. The District of Columbia, portions of Maryland, including the following areas, Anne Arundel, Central and Southeast Howard, Central and Southeast Montgomery, Prince Georges and Southern Baltimore, and portions of northern Virginia, including the following areas, Arlington/Falls Church/Alexandria, Central and Southeast Prince William/Manassas/Manassas Park and Fairfax. * WHEN. From 2 PM EDT this afternoon through this evening. * IMPACTS. Excessive runoff may result in flooding of poor drainage and urban areas and a few small streams. * ADDITIONAL DETAILS. - Thunderstorms this afternoon and evening could have intense rain rates exceeding 2 inches per hour. If locally repetitive or prolonged thunderstorms develop, flash flooding could occur in flood prone urban and suburban areas. - Please visit www.weather.gov/safety/flood for flood safety and preparedness information

* WHAT. Southwest winds 10 to 15 kt with gusts up to 20 kt expected. * WHERE. Tidal Potomac River from Key Bridge to Cobb Island MD, and Chesapeake Bay and adjoining estuaries north of Drum Point MD. * WHEN. From 1 PM this afternoon to 11 PM EDT this evening. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. Heat index values up to 106. * WHERE. Portions of central, north central, northeast, northern and southern Maryland, The District of Columbia and central, northern and northwest Virginia. * WHEN. Until 8 PM EDT this evening. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. Heat index values up to 102. * WHERE. In Maryland, Washington County. In Virginia, Rockingham, Shenandoah, Frederick VA, Page, Warren and Clarke Counties. In West Virginia, Morgan, Berkeley and Jefferson Counties. * WHEN. Until 8 PM EDT this evening. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. Southwest winds 10 to 15 kt with gusts up to 20 kt expected. * WHERE. Tidal Potomac River from Key Bridge to Cobb Island MD, and Chesapeake Bay and adjoining estuaries north of Drum Point MD. * WHEN. From 1 PM this afternoon to 11 PM EDT this evening. * IMPACTS. Conditions will be hazardous to small craft.

* 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, Prince Georges and Southern Baltimore, and northern Virginia, including the following areas, Arlington/Falls Church/Alexandria, Central and Southeast Prince William/Manassas/Manassas Park and Fairfax. * WHEN. From 2 PM EDT this afternoon through 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. * ADDITIONAL DETAILS. - Thunderstorms this afternoon and evening could have intense rain rates exceeding 2 inches per hour. If locally repetitive or prolonged thunderstorms develop, flash flooding could occur in flood prone urban and suburban areas. - Please visit www.weather.gov/safety/flood for flood safety and preparedness information

* WHAT. Heat index values between 100 and 104. * WHERE. Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon, Perry, and York Counties. * WHEN. Until 8 PM EDT this evening. * IMPACTS. High temperatures and high humidity may cause heat illnesses.