Severe Thunderstorm Warning 18, NWS Baltimore/Washington

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
240 PM EDT WED MAY 16 2007

.SYNOPSIS...
COLD FRONT INTO GARRETT COUNTY WILL MOVE E OF THE APLCHNS THIS
AFTN...REACHING CHES BAY THIS EVE. AN UPPER LEVEL DISTURBANCE WILL
PROVIDE COOL TEMPERATURES AND A CHANCE OF SHOWERS THROUGH FRIDAY.
HIGH PRESSURE WILL BUILD OVER THE REGION EARLY NEXT WEEK...BRINGING
WARMER AND DRIER CONDITIONS.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...
SVR TSTM WATCH 278 IN EFFECT. 18Z SNDG IN SYSTEM.

CD FNT MOVG FORWARD ON SCHEDULE. BEST CHC OF SVR WX IS DAMAGING WINDS.
SVR CHC WL BE ENDING THIS EVE.

&&

.SHORT TERM /8 PM THIS EVENING THROUGH 6 AM THURSDAY/...WINDS WILL
SHIFT TO THE NW AFTER THE FRONT...XPCTG WINDS TO DIMINISH ARND MDNGT.
SKIES WILL ALSO CLEAR...MORE SLOWLY ON THE UPSLOPE SIDE OF THE APLCNS.

COLD FRONT IS EAST OF THE FORECAST AREA BY THURSDAY MORNING. AN
UPPER LOW IS OVER EASTERN MICHIGAN...WITH THE TROUGH AXIS EXTENDING
SOUTHWEST INTO ARKANSAS. AS UPPER TROUGH AND ASSOCIATED VORTICITY
MAKE THEIR WAY EAST...PRECIPITATION CHANCES WILL MAKE THEIR WAY BACK
INTO THE FORECAST.

&&

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...

COLD FRONT EXTENDING ALONG THE EASTERN SEABOARD WILL PUSH SLOWLY
EAST INTO THE ATLC AND BECOME STATIONARY AS DEVELOPING SFC LOW RACES
NORTH ALONG IT.  AN UPPER LOW OVER NW PENNSYLVANIA THU EVENING WILL
ROTATE THROUGH THE CWA FRI NIGHT.  GFS AND NAM BEGIN TO DIVERGE AT
THIS POINT WITH GFS H5 LOW LIFTING INTO SOUTHERN NEW ENGLAND BY SAT
AFTERNOON WHILE NAM DRIVES CLOSED LOW TO THE VA/NC COAST.  AS A
RESULT...NAM SFC LOW OFF THE NJ COAST SAT AFTERNOON AND GFS LOW OF
SIMILAR INTENSITY OVER NORTHERN NORTHERN NEW ENGLAND.  I HAVE SAME
CONCERNS AS HPC THAT IF SYSTEM AMPLIFIES SHARPLY EARLY AND IS ABLE
TO SEPARATE FROM THE MAIN WESTERLY FLOW...THE SUBTROPICAL
INTERACTION COULD BE MAXIMIZED AND ALLOW THE VORTEX TO DEEPEN AND
REMAIN CUT OFF FARTHER S AND LONGER...POSING A GREATER THREAT TO THE
ERN SEABOARD.  THUS WILL FAVOR SOLN CLOSER TO NAM.

WILL INTRODUCE CHC SHOWERS THU NIGHT AS UPPER TROF AND ASSOCIATED
PVA MAX ROTATES THROUGH CWA AND CONTINUE THREAT ON FRI. USED A TONED
DOWN VERSION OF HIER GMOS POP VALUES.  A LITTLE LESS CERTAIN OF PCPN
FRI NIGHT AS IT DEPENDS ON POSITION OF LOW...BUT HAVE KEPT A SLIGHT
CHC FOR REGION WITH HIGHEST VALUES NORTHEAST.

UNCERTAIN OF LOW POSITION LATER IN THE WEEKEND.  PRELIMINARY
INDICATIONS ARE THAT ANOTHER COLD FRONT WILL SWING AROUND SYSTEM AND
PASS THROUGH THE MID ATLC REGION SUN AFTERNOON.  PCPN LOOK MINIMAL.
KEPT HPC GUIDE INDICATING SLIGHT CHC POPS NORTH AND EAST.  HIGH PRES
WILL BUILD DOWN OUT OF CANADA BEHIND THE FRONT AND SLIDE OFF ATLC
COAST BY MIDWEEK.  CONDITIONS EXPECTED TO BE DRY WITH MAX TEMPS NEAR
NORMAL IN THE MID 70S.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
TSTMS BIGGEST PROB IN THE FCST AREA THRU 01Z. WINDS TURNING NW
BEHIND IT...ALTHO NOT PROBLEMATIC BEHIND FNT.

VFR WX EXPECTED THROUGH THE WEEKEND.

&&

.MARINE...
SMALL CRAFT CONDITIONS AHEAD OF THE COLD FRONT WILL CONTINUE THROUGH
THE DAY TODAY...THEN FOR THE RMDR OF EVE HRS IN PRES SURGE BEHIND CD
FNTL PASSAGE. WINDS DYING DOWN AFTR MDNGT.

NEAR SCA CONDITIONS MAY DEVELOP FRI AFTERNOON AND CONTINUE INTO SAT
AS DEEPENING LOW PRESSURE MOVES NORTH ALONG THE EASTERN SEABOARD.
WINDSPEEDS AND EXACT DIRECTION OF NORTHERLY WIND COMPONENT WILL BE
DEPENDENT UPON TRACK AND SPEED OF SYSTEM.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT THURSDAY FOR ANZ530>537.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1116 AM EDT WED MAY 16 2007

ANZ530>537-DCZ001-MDZ003>007-009>011-013-014-016>018-501-502-
VAZ021-025>031-036>042-050>057-WVZ050>055-501>504-171100-
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-
DISTRICT OF COLUMBIA-WASHINGTON-FREDERICK MD-CARROLL-
NORTHERN BALTIMORE-HARFORD-MONTGOMERY-HOWARD-SOUTHERN BALTIMORE-
PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT-
EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-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-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-PENDLETON-HARDY-
WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL-
1116 AM EDT WED MAY 16 2007

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING FOR AREAS EAST OF THE APPALACHIANS IN VIRGINIA...CENTRAL
MARYLAND...THE DISTRICT OF COLUMBIA...AND THE CHESAPEAKE BAY AND
TIDAL POTOMAC. THE BEST CHANCE FOR SEVERE WEATHER IS BETWEEN 3 PM
AND 8 PM. DAMAGING WINDS ARE THE PRIMARY THREAT.

A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE MARYLAND
CHESAPEAKE BAY AND TIDAL POTOMAC UNTIL THIS EVENING.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SMALL CRAFT ADVISORY CONDITIONS ARE POSSIBLE ON FRIDAY FOR THE
TIDAL POTOMAC AND MARYLAND PORTION OF THE CHESAPEAKE BAY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN ACTIVATION IS POSSIBLE TODAY.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
341 PM EDT WED MAY 16 2007

VAZ052-162015-
PRINCE WILLIAM/MANASSAS/MANASSAS PARK VA-
341 PM EDT WED MAY 16 2007

...STRONG THUNDERSTORMS TO AFFECT PRINCE WILLIAM COUNTY...MANASSAS
AND MANASSAS PARK...

AT 341 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM 6 MILES
SOUTHWEST OF GREENWICH...MOVING NORTHEAST AT 45 MPH.

THIS STORM WILL BE CAPABLE OF PRODUCING SMALL HAIL AND WIND GUSTS TO
40 MPH.

THE COMMUNITIES OF MANASSAS...MANASSAS PARK...HAYMARKET AND BULL RUN
WILL BE AFFECTED BY THIS STORM.

RESIDENTS IN THESE AREAS SHOULD REMAIN ALERT IN CASE WARNINGS ARE
ISSUED. A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 8 PM.

MANNING

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
343 PM EDT WED MAY 16 2007

MDZ007-162015-
HARFORD MD-
343 PM EDT WED MAY 16 2007

...STRONG THUNDERSTORMS TO AFFECT HARFORD COUNTY...

AT 343 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM 4 MILES
SOUTHWEST OF NORRISVILLE...MOVING NORTHEAST AT 40 MPH.

THIS STORM WILL BE CAPABLE OF PRODUCING SMALL HAIL AND WIND GUSTS TO
40 MPH.

THE COMMUNITIES OF ROCKS...CHROME HILL...PYLESVILLE...STREET...
NORRISVILLE... CARDIFF AND WHITEFORD WILL BE AFFECTED BY THIS STORM.

RESIDENTS IN THESE AREAS SHOULD REMAIN ALERT IN CASE WARNINGS ARE
ISSUED.

MANNING

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