Hail and Damaging Winds in Virginia, August 4, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
221 PM EDT TUE AUG 4 2015

.SYNOPSIS...
A SURFACE TROUGH WILL CONTINUE TO GRADUALLY SHIFT SOUTHEAST
THROUGH THE AREA TODAY. HIGH PRESSURE WILL BUILD INTO THE AREA
LATER TONIGHT THROUGH WEDNESDAY. THE BOUNDARY WILL RETURN NORTH AS
A WARM FRONT AND STALL OUT OVER THE AREA FOR THURSDAY AND FRIDAY.
LOW PRESSURE WILL RIDE ALONG THE BOUNDARY...PASSING THROUGH THE
REGION THURSDAY NIGHT AND FRIDAY. HIGH PRESSURE WILL GRADUALLY
BUILD IN BEHIND THE LOW NEXT WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AN UPPER LOW IS LOCATED NEAR HUDSON BAY WHILE THE JET STREAM
ROUNDS THE TROUGH ACROSS THE GREAT LAKES INTO THE MID- ATLANTIC
THIS AFTERNOON. A SURFACE LOW IS ON THE EAST SIDE OF HUDSON BAY
WHILE A WEAK COLD FRONT...MORE REPRESENTATIVE OF A SURFACE TROUGH
IS DRAPED ACROSS THE NORTHEAST AND ALONG THE I-95 CORRIDOR THIS
AFTERNOON. A COASTAL LOW OFF MYRTLE BEACH WILL MOVE NE AND OUT TO
SEA.

THE SURFACE TROUGH HAS DIVIDED THE MID-ATLANTIC WITH DEWPTS DROPPING
ACROSS THE POTOMAC HIGHLANDS AND TEMPS IN THE MID 80S AND WARM AND
HUMID CONDITIONS EAST OF THE BLUE RIDGE WITH TEMPS IN THE UPPER 80S
ALONG I-95 AND DEWPTS IN THE UPPER 60S TO LOW 70S IN THE SOUTHERN
MD. A CU FIELD HAS FORMED ACROSS MUCH OF THE REGION AS MIXING HAS
OCCURRED. THE CU HAS A FORWARD TILT TO THEM SHOWING SHEAR IN THE MID-
LEVELS. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM NEAR THE
SURFACE TROUGH AXIS AND EAST WITH COVERAGE AND INTENSITY INCREASING
NEAR AND EAST OF I-95 WHERE TEMPS AND DEWPTS ARE HIGH AND
INSTABILITY IS GREATER THAN 1500 J/KG. EFFECTIVE SHEAR RANGES FROM
30-40KTS ACROSS THE REGION. A STABLE LAYER IS APPARENT ON RAP
FCST SOUNDINGS FOR S MD LEADING TO LITTLE CU FIELD ACROSS AREA OF
CONCERN...PIEDMONT AND S MD. THIS SHOULD BE OVERTAKEN THIS
AFTERNOON. THE CONVECTION FROM THE COASTAL LOW NEAR THE MYRTLE
BEACH HAS PRODUCED NORTHWARD MOVING OUTFLOW BOUNDARIES THAT MAY
REACH THE MID-ATLANTIC.

THE BEST CHANCE FOR STRONG TO SEVERE STORMS APPEARS TO BE I-95 AND
EAST INCLUDING SOUTHERN MD...TIDEWATER REGION AND SURROUNDING
WATERS. SEVERE THREATS INCLUDE DMG WINDS...LARGE HAIL AND ISO
TORNADOES.

THE SFC TROUGH MOVES OFF THE COAST THIS EVENING AND HIGH PRESSURE
MOVES INTO THE REGION. FCST MIN TEMPS RANGE FROM THE LOW 60S IN THE
HIGHLANDS TO THE LOW 70S IN COASTAL AREAS INCLUDING THE METROS.

THE GRADIENT BETWEEN HIGH PRESSURE MOVING IN FROM THE WEST AND THE
SFC TROUGH NEAR THE EAST COAST WILL CAUSE NW WINDS 10-15MPH WITH
GUSTS UP TO 25 MPH.

&&

.SHORT TERM /WEDNESDAY NIGHT/...
HIGH PRESSURE CONTINUES TO MOVE INTO THE REGION WEDNESDAY NIGHT.
CLOUDS WILL BEGIN TO INCREASE FROM THE SW INTO THURSDAY MORNING AS
THE NEXT SYSTEM APPROACHES.

A STRONG SHORTWAVE TROUGH ALOFT WILL INDUCE A WAVE OF LOW
PRESSURE ALONG A STALLED FRONTAL BOUNDARY OVER THE OHIO VALLEY
THURSDAY...THEN TRACK BASICALLY DIRECTLY OVER THE CWA THURSDAY
NIGHT INTO FRIDAY. DEEP-LAYER SOUTHERLY FLOW ACROSS THE GULF COAST
INTO THE TENNESSEE/OHIO VALLEYS WILL INFUSE PLENTY OF MOISTURE
INTO THE SYSTEM AS IT APPROACHES THE AREA...WITH PRECIPITABLE
WATER VALUES OF 1.75 TO 2.00 INCHES NEAR AND SOUTH OF THE LOW
TRACK. EXPECTING WIDESPREAD SHOWERS WITH A FEW EMBEDDED CONVECTIVE
ELEMENTS AND POSSIBLY SOME ISOLATED THUNDER GIVEN POTENTIAL MODEST
CAPE/STRONG FORCING. HEAVY DOWNPOURS POSSIBLE...WITH A SOAKING
RAIN EXPECTED OVERALL. 12Z NAM OFFERS WORST CASE WITH 3 TO 5
INCHES OF RAIN BUT THINK THIS IS OVERDONE GIVEN PROGRESSIVE NATURE
OF THE SYSTEM.

LOW PRESSURE PUSHES EAST INTO THE WESTERN ATLANTIC LATER FRIDAY WITH
SHOWERS COMING TO AN END FROM WEST TO EAST. WITH ABUNDANT CLOUDS AND
HIGH HUMIDITY...EXPECT NIGHTTIME TEMPERATURES TO BE AROUND
NORMAL...BUT DAYTIME HIGHS TO BE A FEW DEGREES ON THE COOL SIDE OF
NORMAL.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
HIGH PRESSURE/MID- TO UPPER-LEVEL RIDGING WILL MOVE ACROSS OVER
THE WEEKEND. DRY WEATHER AND SEASONABLY MILD WEATHER IS EXPECTED
DURING THIS TIME.

AS RIDGING BEGINS RE-BUILDING OVER THE SOUTH-CENTRAL CONUS BY EARLY
NEXT WEEK...HEIGHTS WILL BEGIN TO FALL OVER THE GREAT LAKES AND
NORTHEAST. AS THIS HAPPENS...ANOTHER FRONT WILL APPROACH THE AREA
AND INCREASE THE CHANCE FOR SHOWERS AND THUNDERSTORMS NEXT MONDAY
AND TUESDAY.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
SHRA/VCTS POSSIBLE AT CHO-IAD THROUGH THE AFTERNOON AND CONTINUES
FOR DCA-BWI-MTN THROUGH 00Z. SOME TS MAY PRODUCE GUSTY WINDS AND
SMALL HAIL. AT THIS TIME COVERAGE SEEMS LOW TO PUT TSRA IN
TAF...MAY HAVE TO AMD THIS AFTERNOON AND EARLY AFTERNOON.

VFR CONDITIONS EXPECTED TONIGHT AND WEDNESDAY.

WIDESPREAD SUB-VFR EXPECTED BY THU EVE...LASTING INTO
FRI AM IN -RA. WIND VARIABLE AOB 10 KT AS LOW PRES PASSES OVERHEAD.
VFR LIKELY RETURNS BY SAT AM...W/ WINDS BECOMING NWLY AROUND 10 KT.

&&

.MARINE...
SW-W WINDS EXPECTED ON THE WATERS THIS AFTERNOON. SHOWERS AND
THUNDERSTORMS EXPECTED ON THE WATERS THIS AFTERNOON AND EARLY THIS
EVENING. SOME THUNDERSTORMS MAY PRODUCE GUSTY WINDS AND
WATERSPOUTS AND SMW MAY BE WARRENTED. THE BEST CHANCE FOR STRONG
TO SVR STORMS IS ALONG THE TIDAL POTOMAC AND SOUTHER OF BALTIMORE
HARBOR THIS AFTERNOON AND EARLY EVENING.

HIGH PRESSURE WILL MOVE EASTWARD BUT A GRADIENT WILL PERSIST
ACROSS THE WATERS THROUGH WEDNESDAY. A SCA IS IN EFFECT FOR THE
WATERS WEDNESDAY AFTERNOON.

LOW PRESSURE WILL RIDE ALONG A STALLED FRONT AND CROSS THE
WATERS THURSDAY NIGHT INTO FRIDAY. DEPENDING ON THE EXACT TRACK OF
THE LOW...A SMALL CRAFT ADVISORY COULD BE REQUIRED FOR PARTS OF THE
WATERS DURING THIS TIME.

&&

.CLIMATE...
REAGAN NATIONAL AIRPORT /DCA/ HIT AT LEAST 90 DEGREES TODAY FOR
THE 12TH CONSECUTIVE DAY. THIS IS THE LONGEST SUCH STRETCH SINCE
JULY OF 2010...AND THE 15TH LONGEST STRETCH ON RECORD AT THE SITE.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TO 8 PM EDT WEDNESDAY FOR
     ANZ530>532-538>540.
     SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ534-537-
     543.

&&

SYNOPSIS...HAS
NEAR TERM...HAS
SHORT TERM...HAS/DFH
LONG TERM...DFH
AVIATION...HAS/DFH
MARINE...HAS/DFH
CLIMATE...DFH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1043 AM EDT TUE AUG 4 2015

ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-051000-
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-SOUTHERN BALTIMORE-PRINCE GEORGES-
ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT-SOUTHEAST HARFORD-
PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-
ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-
KING GEORGE-
1043 AM EDT TUE AUG 4 2015

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...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING.
A FEW THUNDERSTORMS MAY BECOME SEVERE...ESPECIALLY NEAR AND EAST
OF INTERSTATE 95. SEVERE THREATS ARE DAMAGING WIND GUSTS...LARGE
HAIL AND ISOLATED TORNADOES.

SCATTERED THUNDERSTORMS CAPABLE OF PRODUCING STRONG WINDS ARE
POSSIBLE OVER THE WATERS THIS AFTERNOON AND EVENING.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.
PLEASE RELAY ANY REPORTS OF WIND DAMAGE OR LARGE HAIL FROM
PREVIOUS STORMS EARLY THIS MORNING.

MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053-
055-501>506-051000-
WASHINGTON-FREDERICK MD-CARROLL-NORTHERN BALTIMORE-
EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-
NORTHWEST MONTGOMERY-CENTRAL AND SOUTHEAST MONTGOMERY-
NORTHWEST HOWARD-CENTRAL AND SOUTHEAST HOWARD-NORTHWEST HARFORD-
AUGUSTA-ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-
NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-ORANGE-CULPEPER-
NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND-
EASTERN HIGHLAND-WESTERN LOUDOUN-EASTERN LOUDOUN-
NORTHERN VA BLUE RIDGE-CENTRAL VA BLUE RIDGE-HAMPSHIRE-MORGAN-
BERKELEY-JEFFERSON-HARDY-WESTERN GRANT-EASTERN GRANT-
WESTERN MINERAL-EASTERN MINERAL-WESTERN PENDLETON-
EASTERN PENDLETON-
1043 AM EDT TUE AUG 4 2015

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...TODAY AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. PLEASE RELAY ANY
REPORTS OF WIND DAMAGE OR LARGE HAIL FROM PREVIOUS STORMS EARLY
THIS MORNING.