FXUS61 KLWX 251619
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1119 AM EST WED NOV 25 2009
.SYNOPSIS...
LOW PRESSURE OVER THE GREAT LAKES WILL TRACK INTO ONTARIO TODAY.
AN ATTACHED WEAK COLD FRONT WILL MOVE ACROSS THE AREA THIS EVENING.
LOW PRESSURE WILL FORM OFF THE FLORIDA COAST THIS EVENING...AND
MOVE UP THE EASTERN SEABOARD THANKSGIVING DAY. ANOTHER COLD FRONT
WILL MOVE ACROSS THE MID ATLANTIC THURSDAY NIGHT. HIGH PRESSURE
RETURNS FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW LEVEL EASTERLY FLOW WAS STARTING TO TURN MORE TO THE SOUTHEAST
LATE THIS MORNING...EVEN TO THE SOUTH ACROSS CENTRAL VIRGINIA.
ATMOSPHERE REMAINS MOIST...WITH LOW CIGS ALONG WITH PATCHY FOG AND
SOME DRIZZLE ACROSS THE METRO AREAS AND BAY.
EXPECT DRIZZLE TO PERSIST INTO THE AFTERNOON HOURS IN THE SAME
PLACES ITS OCCURRING THIS MORNING. THERE IS A COLD FRONT
APPROACHING FROM THE WEST...THAT MOVES THROUGH LATE TODAY/THIS
EVENING. FRONT WILL BRING SOME SHOWERS TO THE HIGHLANDS THIS
AFTERNOON...AND WILL HELP TO PROMOTE RISING CIGS. STILL...WITH THE
CLOUDS...TEMPERATURES WILL BE HELD IN THE 50S TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
I HATE USING THE WORD "HOPEFUL" IN A TECHNICAL DSCN BUT I AM
HOPEFUL OF FURTHER IMPRVMNT A CIGS/VSBY DURG THE EVE HRS TO HELP
ALLEVIATE ANY AIRPORT BACKUPS. WK FNT MENTIONED IN THE
SYNOPSIS...WHICH CURRENTLY CAN BE SEEN PRODUCING LGT RA AHD OF IT
IN NE KY...WL BE ENTERING THE MTNS ARND 00Z. BLV ANY RMNG PCPN WL
BE TRACKING N OF THE CWA...BUT THE FNT WL PROMOTE THE MIXING
MENTIONED IN THE ABV SXN THIS EVE. PERHAPS EVEN SOME STARS WL BE
VSBL.
COOLER TEMPS TNGT GIVEN A RETURN TO SFC RADIATION...RANGING FM THE
M30S IN THE MTNS TO M40S CITIES/BAY.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
MODELS IN GENERAL AGREEMENT WITH TRACK OF DEVELOPING COASTAL LOW.
LOPRES OFF THE CAROLINA COAST THU MRNG WILL STRENGTHEN WHILE MOVING
NE UP THE ERN SEABOARD. GFS/SREF ENSEMBLES PROG COASTAL LOW TO BE
ABOUT 200-300 MI E OF KORF BY 00Z FRI. FURTHER UPSTREAM...AN
AMPLIFYING UPPER LOW CENTERED OVER THE OH VLY WILL PROGRESS THRU THE
GREAT LAKES/UPSTATE NY THU NGT. A STRONG LLVL BAROCLINIC ZONE AND
SFC COLD FRONT WILL BE DRAWN EWD THU AFTN AND THU NGT AS THE COASTAL
LOW PUSHES N AND E OF THE MID ATLANTIC REGION AND THE UPPER LOW
ADVANCES EWD TOWARDS THE AREA. MOISTURE AND ENHANCED LIFT FROM
DPVA ASSOCIATED WITH UPPER LOW DOES NOT MOVE INTO THE REGION UNTIL
LATE THU AFTN/THU EVNG. THEREFORE MOST OF THE PRECIP MAY HOLD OFF
THANKSGIVING DAY...ESPECIALLY E OF THE MTS.
COLD POOL ALOFT ASSOCIATED WITH UPPER LOW MOVES OVRHD THU NGT WHILE
STRONG CAA WILL RESULT IN COLDER AND BREEZY CONDITIONS. 00Z NAM/GFS
BUFKIT SOUNDINGS CONTINUE TO SUPPORT PRECIP MIXING AND CHANGING TO
SNOW AFTER SUNSET THU ACROSS THE WRN RIDGES OF THE POTOMAC HIGHLANDS
AND OVRNGT FOR LOCATIONS W OF THE BLUE RIDGE. SNOW MAY START TO
ACCUMULATE ACROSS THE HIGH ELEVATIONS AOB 3 KFT LATE THU EVNG/OVRNGT
WITH THE LOSS OF DAYTIME HEATING AND RAPIDLY COOLING THERMAL
PROFILES.
NEGATIVELY TILTED UPPER TROUGH WILL BE SLOW TO EXIT THE NERN STATES
FRI. DOWNSLOPING WLY FLOW AND STRONG CAA SHOULD DRY THE LLVLS E OF
THE MTS FAIRLY QUICK FRI. STRONG PRESSURE GRADIENT BETWEEN THE
DEPARTING LOW AND HIPRES BUILDING IN FROM THE GULF STATES WILL
RESULT IN BREEZY CONDITIONS FRI. CYCLONIC W-NW FLOW AROUND THE UPPER
LOW WITH A LLVL FETCH FROM THE C GREAT LAKES SUPPORTS A PROLONGED
UPSLOPE SNOW EVENT THRU FRI NGT BEFORE WINDING DOWN SAT WHEN
INVERSION HGTS CRASH. CONFIDENCE IS INCREASING IN WINTER WX ADVISORY
LVL SNOW ACCUMULATIONS ACROSS THE FAVORED WRN SLOPES...BUT STILL TOO
FAR OUT TO NAIL DOWN SNOW TOTALS.
THE FLOW ALOFT WILL BECOME ZONALLY ORIENTED FOR THE WEEKEND WHILE
SFC HIPRES BUILDS IN FROM THE GULF STATES. THIS PATTERN WILL PROVIDE
MODERATING TEMPS AND DRY WX FOR THE WEEKEND. THE NEXT STORM SYSTEM
AND ASSOCIATED COLD FRONT WILL APPROACH THE AREA ERY NEXT WEEK.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
IFR CIGS WILL CONTINUE AT THE HUBS THROUGH AT LEAST 20-21Z...WITH
IFR VSBYS LIKELY TO PERSIST AT KDCA/KBWI /BUT NOT KIAD/ THROUGH
THE SAME TIME. TREND FROM MODELS/GUIDANCE IS FOR CONDITIONS TO
IMPROVE FOR AHWILE THERAFTER /MVFR TO VFR THIS EVENING/...ALTHOUGH
SOME OF THE LATEST LAMP RUNS INDICATE CIGS COULD LINGER A LITTLE
LONGER. WILL ALSO HAVE TO CONSIDER SOME FOG FORMATION
OVERNIGHT...AND ASSOCIATED REDEVELOPMENT OF IFR/LIFR CIGS.
A COLD FRONT WILL MOVE THRU THE AREA THANKSGIVING NGT WITH GUSTY
W-NW WINDS EXPECTED BEHIND THE FRONT LATE THU NGT...LASTING THRU
SAT. WINDS WILL RELAX FOR THE SECOND HALF OF THE WEEKEND AS THE LOW
DEPARTS AND HIPRES BUILDS INTO THE AREA. GENERALLY VFR CIGS EXPECTED
LATE THIS WEEK INTO THE WEEKEND.
&&
.MARINE...
MODELS CONTINUE TO SHOW GOOD CONSISTENCY IN EAST/SOUTHEAST FLOW
REMAINING AOB 10 KT TODAY. WIND SHIFT TO THE NORTHWEST OR NORTH IS
EXPECTED TONIGHT.
A STRONG COLD FRONT WILL MOVE THRU THE WATERS THU NGT WITH
WIDESPREAD SCA CONDITIONS OVRNGT THU THRU SAT. WILL HAVE TO MONITOR
THE POTENTIAL FOR GALE CONDITIONS DURING THE DAYTIME FRI AND SAT
WITH GUSTS TO 30 KT POSSIBLE OVER THE CHSPK BAY. THE FLOW WILL
WEAKEN BY SAT NGT AS HIPRES BUILDS OVER THE REGION.
&&
.TIDES/COASTAL FLOODING...
WATER LEVELS REMAIN ABOVE NORMAL...BY A FOOT TO A FOOT AND A HALF.
HOWEVER...WITH THE RELATIVELY LOW ASTRONOMICAL TIDES NO TIDALFLOODING
ISSUES ARE EXPECTED IN THE NEAR TERM. NEXT HIGH TIDE AT ANNAPOLIS
IS 1118 AM AND EXPECT AROUND 2.3 FEET MLLW AT THAT TIME.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.
&&
$$
PELOQUIN/WOODY!/JRK
