Hail and Damaging Winds in Virginia, May 14, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1131 AM EDT SAT MAY 14 2005

.SHORT TERM (REST OF TODAY)...

SATELLITE TRENDS HAVE SHOWN AN AREA OF MOSTLY SUNNY SKIES HAS
DEVELOPED THIS MORNING ACROSS THE SHENANDOAH VALLEY...PORTIONS OF
NORTHERN VA AND CENTRAL MD. 15Z SFC TEMPERATURES IN THE UPPER 60S
TO LOWER 70S ACROSS THE CWA POINT TOWARD HIGHS IN THE LOWER 80S IN
LINE WITH CURRENT ZONE FORECAST. 13Z RUC...12Z NAM BUFKIT
SOUNDINGS AND MODIFIED 12Z SOUNDING FOR DULLES INDICATING GOOD
INSTABILITY THIS AFTERNOON WITH SB CAPE NEAR 1400 J/KG AND LIFTED
INDICES BETWEEN MINUS 3 AND MINUS 4 C. STRONG TRIGGERING MECHANISM
FOR CONVECTION THIS AFTERNOON APPEARS TO BE MISSING WITH COLD
FRONT FAR TO THE WEST IN THE LOWER OH VALLEY. A FEW OUTFLOW
BOUNDARIES ACROSS THE AREA MAY SERVE AS A FOCUS FOR
CONVECTION...OTHERWISE CELLS WILL DEVELOP AS A RESULT OF
CONVECTIVE TEMPERATURES BEING REACHED THIS AFTERNOON. MODEL
SOUNDINGS PROJECTING 0-6 KM SHEAR OF APPROXIMATELY 40 KT...SO ANY
PULSE CELLS THAT DEVELOP COULD PRODUCE WINDS NEAR OR SLIGHTLY
ABOVE 50 KT. WITH WET BULB ZERO HEIGHT AT NEARLY 11K FT...ANY HAIL
PRODUCED BY THESE STORMS WOULD LIKELY BE SMALL AND BELOW SEVERE
CRITERIA.

HAVE UPDATED ZONES TO REMOVE MORNING WORDING AND ADJUST SKY COVER
EARLY THIS AFTERNOON ACROSS THE SHENANDOAH VALLEY...PORTIONS OF
NORTHERN VA AND CENTRAL MD.

&&

.PREVIOUS DISCUSSION...
(ISSUED 331 AM EDT SAT MAY 14 2005)

SHORT TERM (TODAY THROUGH TONIGHT)...

SHOWERS AND THUNDERSTORMS ARE MAINLY WEST OF THE CWFA AT THIS
TIME...AS DEPICTED FROM THE REGIONAL RADAR LOOP. CURRENTLY
TEMPERATURES ARE IN THE M/U 50S ACROSS THE CWFA...WITH DEWPOINTS IN
THE M/U 40S WITH SOUTHERLY/SOUTHWESTERLY FLOW. CLOUDINESS PERSISTS
MAINLY OVER THE EASTERN CWFA...WITH SOME BREAKS INDICATED IN THE
LATEST OBSERVATIONS OVER THE WESTERN TWO THIRDS.

EXPECT DEWPOINTS TO RISE THROUGHOUT THE DAY...REACHING THE U50S TO
LOWER 60S AS SOUTHWEST WINDS WILL BRING MOISTURE NORTHWARD. THE 45
KT 850MB JET WILL SHIFT EASTWARD TODAY...HOWEVER WEAKENING
SLIGHTLY...AND POSITION ITSELF EAST OF THE BLUE RIDGE BY THE LATE
AFTERNOON INTO THE OVERNIGHT HOURS. WITH BREAKS IN THE
CLOUDS...TEMPERATURES WILL REACH INTO THE UPPER 70S TO NR 80 IN MOST
PLACES THIS AFTERNOON.

THE ETA LOOKS PRETTY GOOD FOR THIS FORECAST PACKAGE. AFTERNOON
INSTABILITY WILL INCREASE...WITH SURFACE BASED CAPES RANGING BETWEEN
1500 TO 2000 AND LIFTED INDICES BETWEEN -4 AND -7. NO STRONG MID
LEVEL SUPPORT IS INDICATED...HOWEVER A WEAK SHORTWAVE IS NOTED.
UPPER LEVEL JET SUPPORT WILL BE MINIMAL. CWFA WILL BE WITHIN THE
WARM SECTOR THIS AFTERNOON...AND CONVECTION IS LIKELY TO FOCUS UPON
ANY LEFTOVER OUTFLOW BOUNDARIES FROM THE OVERNIGHT CONVECTION IN THE
WEST AND A LEE SIDE TROUGH.(ALREADY AN OUTFLOW BOUNDARY IS NOTED
OVER NORTHERN MARYLAND AT THIS TIME.) ISOLATED SEVERE STORMS WILL BE
POSSIBLE THIS AFTERNOON AND WILL MENTION WITHIN AN SPS AND THE HWO.

MEANWHILE...THE COLD FRONT CURRENTLY OVER THE MID SECTION OF THE
COUNTRY WILL CONTINUE TO TREK EASTWARD OVERNIGHT AND BEGIN
APPROACHING THE WESTERN FRINGES OF THE CWFA BY EARLY SUNDAY.

MAIN CHANGES TO TEMPERATURES INCLUDE RAISING THE MAX TEMPS A FEW
DEGREES FOR TODAY. NO CHANGES TO THE OVERNIGHT MINS. HAVE CHANGED
AROUND THE POPS FOR TODAY...TRIED TO ORIENT THE AXIS OF HIGHEST POPS
FROM SAY BALTIMORE TO IAD TO HARRISONBURG.

LONG TERM (SUNDAY THROUGH FRIDAY)...

SUN...COLD FRONT IS STILL SLATED TO MOVE ACROSS THE MID
ATLANTIC...WITH AN AREA OF CONVECTION AHEAD/ALONG THE FRONT...IN
ADDITION TO SOME PRECIP BEHIND THE FRONT. PREFER THE GFS DEPICTION
OF OMEGA/QPF FIELDS. BUMPED POPS UP TO LIKELY ACROSS OUR CWA.
CONVECTION MORE THAN LIKELY WILL BE ONGOING ACROSS OUR WEST IN THE
MORNING...THEN WILL SHIFT EAST AND GALVANIZE ACROSS THE EAST IN
THE AFTERNOON...AS BEST INSTABILITY SHIFTS EAST WITH FORWARD
PROGRESSION OF COLD FRONT. STORMS COULD BECOME MORE ORGANIZED IN
THE AFTERNOON...AND ANY SEVERE THREAT LOOKS TO BE ALONG/EAST OF
THE I-95 CORRIDOR. ORGANIZATION WILL BE VERY DEPENDENT ON AMOUNT
OF DESTABILIZATION THAT CAN OCCUR.

SUN NGT...FRONT MOVES OFFSHORE...WITH LINGERING CHC POPS ACROSS
LOWER SOUTHERN MD AND THE LOWER POTOMAC/CHES BAY. KEPT SOME LOW POPS
FOR REST OF THE CWA IN THE EVENING AS WELL...WITH UPPER LEVEL TROF
LAGGING BEHIND AND ANOTHER SHOT OF UPPER PVA.

MON THROUGH TUE...CYCLONIC FLOW AND COLD AIR ALOFT WILL KEEP SOME
CLOUDS AROUND FOR P/C...ALTHOUGH SUPPORT FOR PRECIP LOOKS NIL AND
KEPT DRY FORECAST.

WED THROUGH FRI...MADE VERY FEW CHANGES TO PREVIOUS FORECAST...ASIDE
FROM MINOR TEMP/DEWPOINT TWEAKS. MODELS CONTINUE TO SHOW INCREASING
CHC FOR PRECIP WED PM INTO THU AS LOW PRESSURE MOVES FROM THE OH
VALLEY INTO CENTRAL/SOUTHERN VA THU. IF GFS TRAJECTORY IS
CORRECT...CHC POPS MAY BE CONFINED ACROSS OUR SW WED PM BEFORE
SPREADING THROUGH THE ENTIRE CWA WED NGT AND THU.

AVIATION...

CIGS SHOULD REMAIN VFR TODAY...BEFORE GOING MVFR THIS EVENING AND
OVERNIGHT. VSBYS WILL BE TEMPORARILY REDUCED TO IFR IN TSRA THIS
AFTERNOON AND EVENING.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FOR ANZ530>537
UNTIL 8 PM SATURDAY.

&&

SHORT TERM...SMITH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1130 AM EDT SAT MAY 14 2005

DCZ001-MDZ002>007-009>011-013-014-016>018-VAZ021-025>031-036>042-
050>057-WVZ048>055-150930-
DISTRICT OF COLUMBIA-ALLEGANY-WASHINGTON-FREDERICK MD-CARROLL-
NORTHERN BALTIMORE-HARFORD-MONTGOMERY-HOWARD-SOUTHERN BALTIMORE-
PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT-HIGHLAND-
AUGUSTA-ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-
NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-FAUQUIER-LOUDOUN-
ORANGE-CULPEPER-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-
ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-
KING GEORGE-GRANT-MINERAL-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-
PENDLETON-HARDY-
1130 AM EDT SAT MAY 14 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MARYLAND WEST OF THE
CHESAPEAKE BAY AND EAST OF GARRETT COUNTY...EASTERN WEST
VIRGINIA...NORTHERN AND CENTRAL VIRGINIA AND WASHINGTON DC.

.DAY ONE...THIS AFTERNOON AND TONIGHT

ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND
EVENING...MAINLY ALONG AND WEST OF THE I-95 CORRIDOR...INCLUDING THE
PANHANDLE OF WV...MUCH OF MD AND NORTHERN VA.

A WARM FRONT WILL MOVE NORTH OVER THE OUTLOOK AREA THIS
AFTERNOON...AND WITH INCREASING INSTABILITY DUE TO AFTERNOON
HEATING...SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP.

ISOLATED SEVERE THUNDERSTORMS THAT DEVELOP WILL BE CAPABLE OF
PRODUCING WIND GUSTS TO 60 MPH. THE HIGHEST THREAT FOR SEVERE
THUNDERSTORMS WILL BE AFTER 4 PM.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

ISOLATED SEVERE THUNDERSTORMS WILL BE POSSIBLE ONCE AGAIN
SUNDAY...MAINLY ALONG AND EAST OF THE I-95 CORRIDOR...AS A COLD
FRONT MOVES EAST OVER THE OUTLOOK AREA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON AND EVENING.

JB