* WHAT. For the Excessive Heat Warning, dangerously hot conditions with heat index values up to 108. For the Heat Advisory, heat index values up to 102 expected. * WHERE. South-central Pennsylvania. * WHEN. For the Excessive Heat Warning, until 8 PM EDT this evening. For the Heat Advisory, from 8 PM this evening to 8 PM EDT Wednesday. * IMPACTS. Heat related illnesses increase significantly during extreme heat and high humidity events.

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. Patapsco River including Baltimore Harbor. * Until 1015 PM EDT. * At 849 PM EDT, strong thunderstorms were located along a line extending from near Havre De Grace to 7 nm northwest of Gunpowder River to 23 nm north of Key Bridge, moving east at 30 knots. HAZARD. Wind gusts 34 knots or greater. SOURCE. Radar indicated. IMPACT. Boaters in small craft could be thrown overboard by suddenly higher winds and waves capsizing their vessel. * Locations impacted include. Turkey Point, North Point State Park, Fort Smallwood Park, Hart Miller Island, Tolchester Beach, Worton Point, Pooles Island, Spesutie Island, Gunpowder River, Northeast River, Sevenfoot Knoll, Havre De Grace, and Aberdeen Proving Ground.

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 945 PM EDT. * At 818 PM EDT, gust fronts were located along a line extending from 24 nm northwest of Key Bridge to 26 nm northwest of Mason Neck State Park to 29 nm west of Quantico, moving east at 30 knots. Strong thunderstorms behind the gust front are also producing wind gusts in excess of 35 knots. HAZARD. Wind gusts 34 knots or greater. SOURCE. Radar indicated. IMPACT. Boaters in small craft could be thrown overboard by suddenly higher winds and waves capsizing their vessel. * Locations impacted include. Widewater, Leesylvania State Park, Smallwood State Park, National Harbor, Quantico, Fort Washington, Tidal Basin, Reagan National Airport, Gunston Hall, Mason Neck State Park, Woodrow Wilson Bridge, Indian Head, Key Bridge, Occoquan Bay, Fort Hunt, and Alexandria.

* WHAT. Heat index values up to 107 expected. * WHERE. Portions of central and north central Maryland and central, northern and northwest Virginia. * WHEN. From 11 AM to 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. Heat index values up to 102 expected. * WHERE. In Maryland, Washington County. In Virginia, Shenandoah, Frederick VA, Page, Warren, Clarke Counties. In West Virginia, Morgan, Berkeley and Jefferson Counties. * WHEN. From 11 AM to 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. Heat index values around 105 expected. * WHERE. Portions of central, northeast, northern and southern Maryland, The District of Columbia and central and northern Virginia. * WHEN. From 11 AM to 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. Heat index values up to 102. * WHERE. Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon, Perry, and York Counties. * WHEN. Until 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.

THE NATIONAL WEATHER SERVICE HAS ISSUED SEVERE THUNDERSTORM WATCH 548 IN EFFECT UNTIL 10 PM EDT THIS EVENING FOR THE FOLLOWING AREAS THIS WATCH INCLUDES THE FOLLOWING ADJACENT COASTAL WATERS CHESAPEAKE BAY NORTH OF POOLES ISLAND MD CHESAPEAKE BAY FROM POOLES ISLAND TO SANDY POINT MD CHESAPEAKE BAY FROM SANDY POINT TO NORTH BEACH MD CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD PATAPSCO RIVER INCLUDING BALTIMORE HARBOR CHESTER RIVER TO QUEENSTOWN MD EASTERN BAY CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER PATUXENT RIVER TO BROOMES ISLAND MD

THE NATIONAL WEATHER SERVICE HAS ISSUED SEVERE THUNDERSTORM WATCH 548 IN EFFECT UNTIL 10 PM EDT THIS EVENING FOR THE FOLLOWING AREAS IN DELAWARE THIS WATCH INCLUDES 3 COUNTIES IN CENTRAL DELAWARE KENT IN NORTHERN DELAWARE NEW CASTLE IN SOUTHERN DELAWARE SUSSEX IN MARYLAND THIS WATCH INCLUDES 4 COUNTIES IN NORTHEAST MARYLAND CAROLINE KENT QUEEN ANNE'S TALBOT IN NEW JERSEY THIS WATCH INCLUDES 16 COUNTIES IN CENTRAL NEW JERSEY MERCER MONMOUTH IN NORTHERN NEW JERSEY HUNTERDON MIDDLESEX MORRIS SOMERSET SUSSEX WARREN IN SOUTHERN NEW JERSEY ATLANTIC BURLINGTON CAMDEN CAPE MAY CUMBERLAND GLOUCESTER OCEAN SALEM IN PENNSYLVANIA THIS WATCH INCLUDES 10 COUNTIES IN EAST CENTRAL PENNSYLVANIA BERKS LEHIGH NORTHAMPTON IN NORTHEAST PENNSYLVANIA CARBON MONROE IN SOUTHEAST PENNSYLVANIA BUCKS CHESTER DELAWARE MONTGOMERY PHILADELPHIA THIS INCLUDES THE CITIES OF ALLENTOWN, ATLANTIC CITY, BETHLEHEM, BLAIRSTOWN, CAMDEN, CENTREVILLE, CHERRY HILL, CHESTERTOWN, DENTON, DEPTFORD, DOVER, DOYLESTOWN, EAST BRUNSWICK, EASTON, EASTON, EDISON, FLEMINGTON, FREEHOLD, GEORGETOWN, GLASSBORO, HAMMONTON, JIM THORPE, MEDIA, MILLVILLE, MOORESTOWN, MORRISTOWN, MOUNT HOLLY, NEW BRUNSWICK, NEWTON, NORRISTOWN, NORTH BRUNSWICK TOWNSHIP, OCEAN CITY, PENNSVILLE, PERTH AMBOY, PHILADELPHIA, READING, SAYREVILLE, SOMERSET, STROUDSBURG, TOMS RIVER, TRENTON, WEST CHESTER, AND WILMINGTON.

SEVERE THUNDERSTORM WATCH 548 REMAINS VALID UNTIL 10 PM EDT THIS EVENING FOR THE FOLLOWING AREAS IN DELAWARE THIS WATCH INCLUDES 3 COUNTIES IN CENTRAL DELAWARE KENT IN NORTHERN DELAWARE NEW CASTLE IN SOUTHERN DELAWARE SUSSEX IN MARYLAND THIS WATCH INCLUDES 4 COUNTIES IN NORTHEAST MARYLAND CAROLINE KENT QUEEN ANNE'S TALBOT IN NEW JERSEY THIS WATCH INCLUDES 14 COUNTIES IN CENTRAL NEW JERSEY MERCER MONMOUTH IN NORTHERN NEW JERSEY HUNTERDON MIDDLESEX MORRIS SOMERSET IN SOUTHERN NEW JERSEY ATLANTIC BURLINGTON CAMDEN CAPE MAY CUMBERLAND GLOUCESTER OCEAN SALEM IN PENNSYLVANIA THIS WATCH INCLUDES 5 COUNTIES IN SOUTHEAST PENNSYLVANIA BUCKS CHESTER DELAWARE MONTGOMERY PHILADELPHIA THIS INCLUDES THE CITIES OF ATLANTIC CITY, CAMDEN, CENTREVILLE, CHERRY HILL, CHESTERTOWN, DENTON, DEPTFORD, DOVER, DOYLESTOWN, EAST BRUNSWICK, EASTON, EDISON, FLEMINGTON, FREEHOLD, GEORGETOWN, GLASSBORO, HAMMONTON, MEDIA, MILLVILLE, MOORESTOWN, MORRISTOWN, MOUNT HOLLY, NEW BRUNSWICK, NORRISTOWN, NORTH BRUNSWICK TOWNSHIP, OCEAN CITY, PENNSVILLE, PERTH AMBOY, PHILADELPHIA, SAYREVILLE, SOMERSET, TOMS RIVER, TRENTON, WEST CHESTER, AND WILMINGTON.

THE NATIONAL WEATHER SERVICE HAS ISSUED SEVERE THUNDERSTORM WATCH 548 IN EFFECT UNTIL 10 PM EDT THIS EVENING FOR THE FOLLOWING AREAS THE DISTRICT OF COLUMBIA IN MARYLAND THIS WATCH INCLUDES 12 COUNTIES IN CENTRAL MARYLAND ANNE ARUNDEL HOWARD MONTGOMERY PRINCE GEORGES IN NORTH CENTRAL MARYLAND CARROLL FREDERICK IN NORTHEAST MARYLAND CECIL IN NORTHERN MARYLAND BALTIMORE BALTIMORE CITY HARFORD IN SOUTHERN MARYLAND CALVERT CHARLES IN VIRGINIA THIS WATCH INCLUDES 18 COUNTIES IN CENTRAL VIRGINIA CITY OF FREDERICKSBURG KING GEORGE ORANGE SPOTSYLVANIA IN NORTHERN VIRGINIA ARLINGTON CITY OF ALEXANDRIA CITY OF FAIRFAX CITY OF FALLS CHURCH CITY OF MANASSAS CITY OF MANASSAS PARK CULPEPER FAIRFAX FAUQUIER LOUDOUN PRINCE WILLIAM STAFFORD IN NORTHWEST VIRGINIA MADISON RAPPAHANNOCK THIS INCLUDES THE CITIES OF ABERDEEN, ALEXANDRIA, ANNAPOLIS, ARLINGTON, ARNOLD, ASPEN HILL, BALLENGER CREEK, BALTIMORE, BEL AIR, BETHESDA, BOWIE, CAMP SPRINGS, CATONSVILLE, CHANTILLY, CHESAPEAKE BEACH, CLINTON, COLLEGE PARK, COLUMBIA, CULPEPER, DAHLGREN, DUNDALK, DUNKIRK, EDGEWOOD, ELDERSBURG, ELKTON, ELLICOTT CITY, ESSEX, FAIRFAX, FALLS CHURCH, FALLSTON, FALMOUTH, FREDERICK, FREDERICKSBURG, GAITHERSBURG, GERMANTOWN, GLEN BURNIE, GORDONSVILLE, GREENBELT, HAVRE DE GRACE, HERNDON, HUNTINGTOWN, JOPPATOWNE, LAUREL, LEESBURG, LUSBY, MADISON, MANASSAS, MANASSAS PARK, MCLEAN, NORTH BEACH, ODENTON, ORANGE, PARKVILLE, PIKESVILLE, POTOMAC, PRINCE FREDERICK, RANDALLSTOWN, RESTON, ROCKVILLE, SEVERN, SEVERNA PARK, SILVER SPRING, SOUTH GATE, SPOTSYLVANIA COURTHOUSE, ST. CHARLES, STERLING, SUITLAND-SILVER HILL, TOWSON, WALDORF, WARRENTON, WASHINGTON, WASHINGTON, WESTMINSTER, AND WOODBRIDGE.