000
FXUS61 KLWX 201614
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1114 AM EST THU NOV 20 2008
.SYNOPSIS...
CLIPPER SYSTEM TO MOVE ACROSS THE AREA THROUGH FRIDAY. HIGH
PRESSURE BUILDS IN THIS WEEKEND...BEFORE ANOTHER STRONG UPPER
STORM SYSTEM MOVES INTO THE REGION MONDAY THROUGH TUESDAY.
IMPROVING CONDITIONS ARE EXPECTED FOR THE THANKSGIVING HOLIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
COLD FRONT/CLIPPER SYSTEM CURRENTLY OVER THE EASTERN PANHANDLE OF
WEST VIRGINIA STRETCHING THROUGH THE SHENANDOAH VALLEY. NO PRECIP IS
ASSOCIATED WITH THIS FEATURE AT THIS TIME. HOWEVER...UPSLOPE SNOW
SHOWERS ARE EXPECTED ALONG THE WESTERN FACING RIDGES THIS AFTERNOON
AND OVERNIGHT.
WINDS HAVE SHIFTED TO THE WEST BEHIND THE BOUNDARY. SEVERAL BREAKS
IN THE OVERCAST HAVE OCCURRED. SKIES EAST OF THE HIGHLANDS SHOULD
REMAIN PARTLY SUNNY/MOSTLY CLOUDY FOR THE REMAINDER OF THE AFTERNOON.
HAVE ALSO RAISED THE MAX T NUMBERS A FEW DEGREES.
HAVE ADJUSTED THE SUSTAINED WINDS/WIND GUSTS FOR THE REMAINDER OF
THE MORNING AND INTO THE AFTERNOON. GUSTS TO BETWEEN 25 AND 30 KT
WILL BE LIKELY OVER THE HIGHER TERRAIN OUT WEST. GUSTS AROUND 20 KT
WILL BE LIKELY OVER THE REMAINING LAND AREAS.
HAVE GONE AHEAD AND ISSUED A WINTER STORM WARNING FOR THE FAR
WESTERN THREE ZONES. AN ADVISORY HAS BEEN ISSUED FOR EASTERN
ALLEGANY...MINERAL...GRANT AND HAMPSHIRE AND HARDY COUNTIES.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
UPSLOPE SNOW SHOWERS REALLY PICK UP OVERNIGHT. MAIN CHALLENGE FOR
TONIGHT IS THE HEADLINE. THERE IS CURRENTLY A WINTER STORM WATCH IN
EFFECT FOR THE WESTERN FIVE ZONES. WHILE THERE WILL BE SOME MINOR
ACCUMULATIONS IN THE HIGHER TERRAIN DURING THE LATE AFTERNOON...THIS
EVENT WILL NOT REALLY BEGIN UNTIL TONIGHT. CONFIDENCE IS NOT HIGH
ENOUGH TO UPGRADE TO A SECOND PERIOD WARNING. THEREFORE...WILL LEAVE
HEADLINES INTACT. AT THIS TIME...EXPECT AROUND 1 TO 3 INCHES TOTAL
ACCUMULATION OVERNIGHT IN THE HEADLINED AREA. SNOW SHOWERS WILL
SPREAD EAST ACROSS THE POTOMAC HIGHLANDS THIS EVENING...THEN
TOWARDS THE BALTIMORE METRO AFTER MIDNIGHT. ACCUMULATION FURTHER
EAST WOULD BE LESS THAN AN INCH AND WOULD NOT BE INCLUDED IN THE
ZONE WORDING.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
DP UPR TROF OVER APLCN MTS WILL BE IN PLACE FRI MRNG...WITH SNOW
EVENT XPCD TO BE ONGOING HIGH TERRAIN OF WRN ZONES. TOTAL
ACCUMULATIONS 4-6IN PSBL FOR UPSLP AREAS OVER 24 HRS. WILL RETAIN
WATCH ATTM...GIVEN LOW CONFIDENCE IN DVLPMT OF WRNG CRITERIA
CONDITIONS.
DRY SLOT FCST TO IMPACT SRN SECTIONS OF CWA...BUT PCPN MAY WRAP
AROUND CIRCULATION INTO NRN AND ERN ZONES. WITH COLD AIR IN
PLACE...ANY PCPN SHUD BE MIX OF RAIN AND SNOW...EVEN INTO METRO
AREAS BY FRI AFTN. NO SGFNT ACCUMULATIONS XPCD.
NWLY FLOW IN WAKE OF UPR TROF WILL CONT MSTR FETCH FROM GRTLKS
RGN...WITH PSBLTY OF LGT SNOW SHOWERS CONTG ON HIGHER TERRAIN FRI
EVE. BY EARLY SAT MRNG...SFC HIPRES BUILDS...WITH LGT LOW LVL
WINDS. DRY WX FCST THRU WKEND.
STG SHRTWV TROF DPNS ACRS N CNTRL CONUS SUN EVE...WITH SWLY FLOW
ALOFT OVER MID ATLC RGN. AS SYSTEM APRCHS...SFC CYCLOGENESIS OVER
GRTLKS RGN WILL INDUCE WARM ADVCTN PATTERN OVER MID ATLC. ALTHOUGH
MSTR RETURN WILL BE LMTD...SLY FLOW SHUD BE SUFFICIENT TO ERODE
LOW LVL COLD AIR SUCH THAT PCPN MON WILL BE LIQUID XCPT HIGH
TERRAIN.
TROF AXIS PASSES THRU TUE...DRIVING CDFNT THRU FCST AREA. WITH
COLD AIR ADVCTN TUE AFTN...MAXIMA MAY BE REACHED EARLY...AND LGT
SNOW SHUD SPREAD EWD THRU TUE. ACCUMULATING SNOW WILL BE PSBL IN
FAVORED UPSLP AREAS TO W...AS SUSTAINED NWLY LOW LVL FLOW XPCD IN
WAKE OF CDFNT.
HIPRES BUILDS AFTER DEPARTURE OF SYSTEM WED AFTN...WITH COOL TEMPS
FCST THRU REMAINDER OF NEXT WK.
&&
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
CIGS WILL REMAIN VFR INTO THE AFTERNOON HOURS. CIG HEIGHTS BETWEEN
045 AND 070 ARE ANTICIPATED. A WIND SHIFT TO THE W/NW IS EXPECTED
LATER THIS MORNING AND AFTERNOON. WINDS GUSTS TO AROUND 20 KT ARE
POSSIBLE. SNOW SHOWERS WILL BEGIN OVER THE MOUNTAINS LATER THIS
MORNING...INTENSIFYING AND SPREADING EAST OVERNIGHT. ADDED
VICINITY SHOWERS AT KMRB FOR TONIGHT...BUT KEPT EVERYWHERE ELSE
DRY. WINDS WILL INCREASE BEHIND THE CLIPPER SYSTEM TODAY...SO
MAINTAINED A BRIEF PERIOD OF GUSTS OF 20 TO 25 KNOTS THIS
AFTERNOON.
INCRG CHC FOR PCPN...LOW CIGS AND VSBYS AS STG UPR TROF MOVES ACRS
RGN THRU FRI. SFC HIPRES AND IMPROVING CONDITIONS THIS WKEND...BFR
ANOTHER STG SYSTEM APRCHS SUN NGT AND MON. CONDITIONS WORSEN MON
THRU TUE ACRS TERMINALS AS RAIN AND SNOW DVLP WITH ARRIVAL AND
PASSAGE OF CDFNT TUE MRNG.
&&
.MARINE...
HAVE SEEN SOME WIND GUSTS BETWEEN 25 AND 30 KT BEHIND THE FRONTAL
BOUNDARY. HAVE GONE AHEAD AND UPPED THE GUSTS POTENTIAL OVER THE
WATERS TO 25 KT THIS AFTERNOON. WINDS WILL BE SLOW TO DIMINISH
OVERNIGHT WITH LOW PRESSURE STRENGTHENING OFF THE EAST COAST.
SMALL CRAFT ADZY CONDITIONS TO CONT THRU FRI AS COLD AIR SPREADS
ATOP WARM WATERS AND UPR TROF AXIS MOVES THRU. SFC HIPRES BUILDS
THRU WKEND...WITH STG UPR SYSTEM TO APRCH MON. SLY LOW LVL FLOW
MON WITH INCRG CHC OF PCPN MON THRU TUE.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 10 PM EST
FRIDAY FOR MDZ501.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 PM EST
FRIDAY FOR MDZ502.
VA...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 10 PM EST
FRIDAY FOR VAZ021.
WV...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 10 PM EST
FRIDAY FOR WVZ054-501-503.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 PM EST
FRIDAY FOR WVZ050-055-502-504.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST FRIDAY FOR ANZ530>537.
&&
$$
UPDATE...LISTEMAA
