Severe Thunderstorm Warning 98, NWS Baltimore/Washington

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
228 PM EDT TUE JUN 25 2013

.SYNOPSIS...
BERMUDA HIGH PRESSURE WILL PERSIST THROUGH THE MIDDLE OF THIS WEEK.
A COLD FRONT WILL APPROACH THE REGION THURSDAY BEFORE STALLING
OVER THE AREA FRIDAY. A TROUGH OF LOW PRESSURE WILL IMPACT THE
AREA DURING THE WEEKEND AND EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE SUBTROPICAL RIDGE REMAINS OVER THE SOUTHERN CONUS WHILE
SURFACE HIGH PRESSURE EXTENDS FROM THE SOUTHEASTERN CONUS OUT INTO
THE ATLANTIC. A ZONAL FLOW AROUND THE SUBTROPICAL RIDGE WILL
CONTINUE OVER OUR AREA THROUGH TONIGHT.

A WEST-SOUTHWEST FLOW AROUND THE SURFACE HIGH HAS CAUSED HOT AND
HUMID CONDITIONS THIS AFTERNOON. MAX TEMPS WILL RANGE FROM NEAR 80
IN THE MOUNTAINS TO THE LOWER AND MIDDLE 90S ACROSS MOST OTHER
LOCATIONS. HEAT INDICES WILL TOP OFF AROUND 100 DEGREES IN THE
URBAN CORRIDORS AROUND WASHINGTON DC AND BALTIMORE.

THE HEAT AND HUMIDITY HAS LED TO AN UNSTABLE ATMOSPHERE. LATEST
MESOANALYSIS SHOWS AROUND 1500 J/KG. HOWEVER...THE CAPPING
INVERSION HAS HELD IN PLACE ACROSS MOST AREAS...MOST LIKELY DUE TO
A DOWNSLOPING COMPONENT TO THE LOW LEVEL FLOW AND MID-LEVEL
SUBSIDENCE BEHIND A DEPARTING VORT MAX. CURRENT THINKING IS THAT
SURFACE HEATING ALONG WITH FORCING FROM A SURFACE TROUGH SHOULD BE
ENOUGH TO OVERCOME THE CAPPING INVERSION FOR ISOLATED/SCATTERED
THUNDERSTORMS THIS AFTERNOON. SOME THUNDERSTORMS WILL BE CAPABLE
OF PRODUCING LOCALLY DAMAGING WIND GUSTS AND LARGE HAIL.

TONIGHT...MCS ACTIVITY CONTINUES TO MOVE OVER THE GREAT LAKES AND
THE OUTFLOW BOUNDARY FROM THIS ACTIVITY HAS MOVED INTO THE OHIO
VALLEY. CONVECTION HAS INITIATED AHEAD THIS BOUNDARY OVER THE OHIO
VALLEY. THE CONVECTION IS LIKELY TO BECOME MORE ORGANIZED AS IT
PROPAGATES EAST TOWARD OUR WESTERN CWA THIS EVENING. THERE IS
LITTLE CERTAINTY AS TO WHETHER OR NOT IT WILL SURVIVE EAST OF THE
MOUNTAINS...BUT WITH A WESTERLY FLOW ALOFT AND MODERATE
INSTABILITY THERE IS A CHANCE FOR SHOWERS AND THUNDERSTORMS TO
IMPACT OUR AREA TONIGHT. SHOULD THE CONVECTION HOLD TOGETHER OR
DEVELOP INTO AN MCS...THEN SEVERE THUNDERSTORMS ARE POSSIBLE. THE
BEST CHANCE FOR THE STRONGER STORMS WILL BE ACROSS THE NORTHERN
PORTION OF THE CWA WHERE THE MID AND UPPER-LEVEL FLOW IS STRONGER.
MIN TEMPS WILL RANGE FROM THE UPR 60S W OF THE BLUE RIDGE TO THE
LOW 70S EAST OF THE BLUE RIDGE...WITH MID 70S IN URBAN/NEAR SHORE
LOCALES.

PATCHY FOG IS EXPECTED OVERNIGHT...ESPECIALLY IN THE SHELTERED
VALLEYS AND RURAL AREAS.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
HIGH PRESSURE WILL REMAIN OVER THE ATLANTIC OCEAN WEDNESDAY AND A
WEST-SOUTHWEST FLOW AROUND THIS SYSTEM WILL CONTINUE TO USHER IN
HOT AND HUMID CONDITIONS. HEAT INDICES AROUND 100 DEGREES ARE
EXPECTED FOR LOCATIONS EAST OF THE BLUE RIDGE MOUNTAINS. THE HEAT
AND HUMIDITY WILL LEAD TO MODERATE AMOUNTS OF INSTABILITY.
SHORTWAVE ENERGY IN A WESTERLY FLOW ALOFT ALONG WITH A SURFACE
TROUGH WILL ACT AS LIFTING MECHANISMS FOR MORE CONVECTION
WEDNESDAY. SOME THUNDERSTORMS WILL BE CAPABLE OF PRODUCING LOCALLY
DAMAGING WIND GUSTS AND LARGE HAIL.

LOW PRESSURE AND ITS ASSOCIATED COLD FRONT WILL APPROACH THE AREA
WEDNESDAY NIGHT BEFORE MOVING INTO THE REGION THURSDAY. MORE
SHOWERS AND THUNDERSTORMS ARE LIKELY LATE WEDNESDAY NIGHT AND
THURSDAY. THERE IS AN INCREASED CHANCE FOR SEVERE THUNDERSTORMS
DURING THIS TIME DUE TO MODERATE INSTABILITY AND INCREASED SHEAR
PROFILES. A FEW SHOWERS AND T-STORMS MAY HANG AROUND OVERNIGHT
THURSDAY AS THE FRONT REMAINS NEAR OUR AREA.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
THE COLD FRONT WILL DISSIPATE OVERHEAD FRIDAY AND A LONGWAVE
UPPER-LEVEL TROUGH IS EXPECTED TO BUILD OVER THE MIDWEST DURING
THE WEEKEND THROUGH EARLY NEXT WEEK. SURFACE HIGH PRESSURE WILL
REMAIN OVER THE ATLANTIC OCEAN DURING THIS TIME AND A SOUTHERLY
FLOW WILL CONTINUE TO USHER IN WARM AND HUMID CONDITIONS. THE WARM
AND HUMID AIRMASS WILL COMBINE WITH FORCING FROM THE UPPER-LEVEL
TROUGH TO BRING UNSETTLED CONDITIONS DURING THIS TIME.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS AFTERNOON
AND EVENING. SOME THUNDERSTORMS WILL HAVE THE POTENTIAL TO PRODUCE
GUSTY WINDS AND HAIL. PATCHY FOG/BR ARE EXPECTED LATE TONIGHT AND
EARLY WEDNESDAY MORNING.

SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THROUGH THE END OF THE
WEEK WITH THE BEST CHANCE IN THE AFTERNOON AND EVENING. MVFR/IFR
CONDITIONS ARE POSSIBLE DURING THE EARLY MORNING HOURS EACH DAY.

&&

.MARINE...
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS AFTERNOON
AND POSSIBLY TONIGHT. THUNDERSTORMS WILL HAVE THE POTENTIAL TO
PRODUCE GUSTY WINDS AND HAIL. SOUTHWEST WINDS ARE EXPECTED THROUGH
TONIGHT WITH GUSTS AROUND 15 KNOTS.

SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THROUGH THE END OF THE
WEEK WITH THE BEST CHANCE IN THE AFTERNOON AND EARLY EVENING. HOT
AND HUMID CONDITIONS AND A SOUTHERLY FLOW WILL CONTINUE DURING
THIS TIME.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

SYNOPSIS...BAJ/HAS
NEAR TERM...BJL
SHORT TERM...BJL
LONG TERM...HAS
AVIATION...BJL/HAS
MARINE...BJL/HAS

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
905 PM EDT TUE JUN 25 2013

ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057-
261215-
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-
CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA-
TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD-
TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD-
TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA-
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-
TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH
ISLAND-DISTRICT OF COLUMBIA-NORTHERN BALTIMORE-HARFORD-
SOUTHERN BALTIMORE-PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-
CALVERT-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-
ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-
KING GEORGE-
905 PM EDT TUE JUN 25 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE
CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN
CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF
COLUMBIA.

.DAY ONE...TONIGHT

SEVERE THUNDERSTORM WATCH 367 IS IN EFFECT FOR MUCH OF THE
INTERSTATE 95 CORRIDOR OF EASTERN MARYLAND AND NORTHERN
VIRGINIA...INCLUDING MUCH OF THE MARYLAND CHESAPEAKE BAY AND TIDAL
POTOMAC RIVER...THROUGH 2 AM. DAMAGING WIND GUSTS FROM AN
APPROACHING LINE OF SEVERE THUNDERSTORM WILL BE THE MAIN THREAT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

AN ISOLATED SEVERE THUNDERSTORM THREAT IS EXPECTED AGAIN FOR
WEDNESDAY AFTERNOON INTO THE EVENING.

HEAT INDICES AROUND 100 DEGREES ARE EXPECTED WEDNESDAY
AFTERNOON AND EARLY EVENING...ESPECIALLY IN THE URBAN CENTERS OF
BALTIMORE AND WASHINGTON DC.

AN INCREASED SEVERE THUNDERSTORM THREAT IS EXPECTED IN ASSOCIATION
WITH A COLD FRONT THURSDAY AND POSSIBLY FRIDAY.

A SMALL CRAFT ADVISORY MAY BE NEEDED THURSDAY AND FRIDAY FOR
PORTIONS OF THE WATERS.

.SPOTTER INFORMATION STATEMENT...

SKYWARN HAS BEEN ACTIVATED. PLEASE RELAY REPORTS OF SEVERE WEATHER
TO THE NATIONAL WEATHER SERVICE.

MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504-
WVZ050>053-055-501>506-261215-
WASHINGTON-FREDERICK MD-CARROLL-MONTGOMERY-HOWARD-
EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-AUGUSTA-
ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-NELSON-
ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-LOUDOUN-ORANGE-CULPEPER-
NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND-
EASTERN HIGHLAND-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-HARDY-
WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL-
WESTERN PENDLETON-EASTERN PENDLETON-
905 PM EDT TUE JUN 25 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN WEST VIRGINIA...
NORTHERN AND CENTRAL VIRGINIA...AND CENTRAL AND WESTERN MARYLAND
WITH THE EXCEPTION OF GARRETT COUNTY.

.DAY ONE...TONIGHT

SEVERE THUNDERSTORM WATCH 365 IS IN EFFECT FOR MUCH OF THE POTOMAC
HIGHLANDS AND PORTIONS OF THE NORTHERN SHENANDOAH VALLEY...
INCLUDING PORTIONS OF NORTH CENTRAL MARYLAND AND EXTREME NORTHERN
VIRGINIA...THROUGH 2 AM. SCATTERED THUNDERSTORMS ARE EXPECTED
ACROSS THESES AREAS LATE TONIGHT...WITH DAMAGING WIND GUSTS THE
MAIN THREAT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

AN ISOLATED SEVERE THUNDERSTORM THREAT IS EXPECTED AGAIN FOR
WEDNESDAY AFTERNOON INTO THE EVENING.

HEAT INDICES WILL APPROACH 100 DEGREES WEDNESDAY AFTERNOON AND
EARLY EVENING FOR LOCATIONS EAST OF THE BLUE RIDGE MOUNTAINS.

AN INCREASED SEVERE THUNDERSTORM THREAT IS EXPECTED IN ASSOCIATION
WITH A COLD FRONT THURSDAY AND POSSIBLY FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN HAS BEEN ACTIVATED. PLEASE RELAY REPORTS OF SEVERE WEATHER
TO THE NATIONAL WEATHER SERVICE.

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
840 PM EDT TUE JUN 25 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0332 PM     TSTM WND DMG     2 WNW LEESBURG          39.11N  77.60W
06/24/2013                   LOUDOUN            VA   NWS EMPLOYEE

            10-15 LARGE TREES 18-24 INCH DIA UPROOTED LARGE LIMBS
            DOWN AND BLOCKING W AND OD TRAIL AT MILE MARKER 37.

&&

CORRECTED LOCATION

EVENT NUMBER LWX1300505

LEE