FXUS61 KAKQ 262029
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
329 PM EST THU NOV 26 2009

.SYNOPSIS...
WEAK HIGH PRESSURE REMAINS OVER THE REGION TODAY. A STRONG COLD 
FRONT WILL MOVE THROUGH THURSDAY NIGHT...PROVIDING A CHANCE FOR 
SHOWERS. AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES ACROSS THE MID 
ATLANTIC STATES ON FRIDAY...THEN HIGH PRESSURE BUILDS IN FROM THE 
WEST OVER THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
RECENT STLT VIS LOOPS SHOW FOG/STRATUS REMAINING FAIRLY WIDESPREAD
N OF I-64. VSBYS HAVE COME UP ABV 1SM IN MOST AREAS...AS FOR MOST
AREAS THE FOG CONTINUES TO TRANSITION INTO STRATUS. CONTINUED WEAK
NE (ONSHORE) FLOW ALONG WITH LATE NOV SUN ANGLE IS LIMITING THE
LLVL MIXING AND THUS DRY AIR ENTRAINMENT FROM ALOFT...AS LATEST
LAPS/RUC SOUNDINGS SHOW SFC-BASED INVERSION REMAINING FAIRLY
STRONG. 

EXPECT A CONTINUED SLOW LLVL DRYING PROCESS THROUGH THE AFTN...
ESPECIALLY WITH THE ABSENCE OF WESTERLY (DOWNSLOPING) FLOW IN THE
BNDRY LAYER. SO...HAVE TRIMMED MAX TEMP FCSTS OVER PTNS OF THE REGION...
MAINLY NRN AREAS WHERE THE SUN HAS YET TO SHINE. HIGHS MID/UPR 50S
N TO LOW/MID 60S S.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
ONCE THE COLD FRONT EXITS THE COAST EARLY FRIDAY MORNING...THE
COLD AIR WILL HELP TIGHTEN THE THERMAL GRADIENT WHICH WILL HELP
INVIGORATE THE AREA OF LOW PRESSURE THAT IS LIFTING NE ALONG THE
COAST. THIS LOW WILL INTENSIFY OFF THE NEW ENGLAND COAST. THIS
WILL HELP THE NW FLOW TO STRENGTHEN. THIS WILL LEAD TO A CLEARING
PATTERN WITH THE DOWNSLOPE FLOW AND ALSO ALLOW FOR GOOD MIXING IN
THE COLD ADVECTION. EXPECT TO SEE GUSTY CONDITIONS ON FRIDAY...BUT
IT SHOULD BE DRY AND COOL. 850 MB TEMPS ARE AROUND -2C TO -4C.
THIS ONLY SUPPORTS HIGHS IN THE LOW TO MID 50S UNDER FULL SUN. 

THE STRONG LOW AND UPPER TROUGH SLIDE OFF THE COAST FRIDAY
NIGHT...WHICH ALLOW THE FLOW TO WEAKEN...BUT IT WILL STILL BE COLD
WITH SOME LOCATIONS GOING BELOW FREEZING OVER CENTRAL VA. AS
RIDGING BUILD EAST ALOFT...WILL SEE A WARM ADVECTION PATTERN
DEVELOP SO TEMPERATURES WILL BEGIN TO MODERATE AND WITH VERY DRY
AIR AROUND...EXPECT SUNNY CONDITIONS WITH LIGHT WINDS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
ONCE AGAIN...HAVE INCORPORATED THE LATEST HPC GUIDANCE FOR THE 
EXTENDED PERIOD...WHICH IS LARGELY BASED ON THE ECMWF. THE ECMWF 
CONTINUES TO SHOW MORE FVRBL RUN-TO-RUN CONSISTENCY WITH 
TIMING/LOCATION OF SYNOPTIC FEATURES EARLY-MID WEEK...MOST NOTABLY 
WITH THE NEXT COLD FRONT MON NIGHT AND TUE...AND THE POTENTIAL FOR 
YET ANOTHER DUAL-LOW SCENARIO TAKING SHAPE BY MID-WEEK AS A 
DEEPENING LOW DROPS INTO THE NRN MS VLY...WHILE LOW PRES FORMS ALONG 
THE EXITING LLVL FRONT/BAROCLINIC BOUNDARY (WRN PERIPHERY OF GULF 
STREAM) JUST OFF THE SE-MID ATLC COAST.

CONTINUED FAIR CONDITIONS WITH MODERATING TEMPS ON TAP FOR SUN TO 
WRAP UP THE HOLIDAY WEEKEND. HIGHS THROUGH THE 60S (LOW-MID 60S N...
MID/UPR 60S S)...CONSISTENT WITH THE LLVL THICKNESS. ECMWF STILL 
SLOWER WITH THE FROPA EARLY NEXT WEEK...THOUGH RECENT GFS RUNS HAVE 
TRENDED TOWARD THE ECMWF (WHICH IS AGAIN A GOOD SIGN FOR THE ECMWF'S 
CREDIBILITY WITH THIS EVOLVING PATTERN). DEPENDING ON HOW QUICKLY WE 
SEE INCREASING CLOUDS/RAIN CHCS MOVING IN FROM THE W...TEMPS CAN GET 
QUITE MILD ONCE AGAIN BASED ON THE PROJECTED LLVL THICKNESS 
STRUCTURE. FOR NOW...HAVE FCSTD UPR 50S OVER FAR NW PTNS TO MID/UPR 
60S FAR SE. 

SHOWERS WITH THE FROPA MOST LIKELY MON NIGHT AND TUE...AND AS SUCH 
HAVE RAISED POPS TO 40-50% (STILL TOO EARLY TO GO HIGHER BASED ON 
THE HIGH PROBABILITY OF TIMING ERRORS 5-6 DAYS AWAY). ANOTHER SWATH 
OF SYNOPTIC "STRATIFORM" RAIN/DRIZZLE LOOKS LIKE A GOOD POSSIBILITY 
BY WED-THU...AS ANOTHER LOW FORMS OFF THE SE CST ALONG THE LLVL 
BAROCLINIC ZONE AND TRACKS NE.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
SKIES ARE MOSTLY VFR THIS AFTN EXCEPT ON THE EASTERN SHORE AS
FOG/STRATUS BURNED OFF LATE THIS AM. WNDS ARE GENLY LGT AND VRBL
BUT WILL GRADUALLY TREND NE-N-NW THRU THE LATE EVENING AND
OVERNIGHT AS COASTAL LOW MOVES NORTH AND FRONT APPROACHES FROM THE
WEST. ANOTHER LOW MOVG THRU GRT LAKES AREA WILL DROP SE AND GET
ABSORBED INTO LARGER FLOW OF THE COASTAL LOW. COMBINED WITH THE
FRONT...CLOUDS WILL INCREASE ACROSS THE REGION TONIGHT AND BRING A
CHC OF -RA INTO THE AREA INTO EARLY FRI.  

BIGGER OPERATIONAL CONCERN GOING FORWARD LOOKS TO BE WITH GUSTY WNDS 
LATE TONIGHT AND FRIDAY AS A COLD FNT CROSSES THE REGION AFTER
MIDNIGHT INTO ERY FRI AM. WNDS BEHIND THE FNT BECOME W/NW WHICH
WL USHER IN DRIER AIR. TIGHTENING PRESSURE GRADIENT BETWEEN COASTL LOW
AND APPROACHING SFC RIDGE TO THE SOUTH WL ALLOW FOR BREEZY TO
WINDY CONDITIONS FRI AFTN...WITH GUSTS TO 20-30KT POSSIBLE DURING
THIS PERIOD. OTW...LOOK FOR MAINLY VFR CONDS BY LATE AM/ERLY PM FRI
AND THROUGH THE WEEKEND. NEXT CHC OF PCPN LOOKS TO BE LATE MON
INTO TUE.

&&

.MARINE...
SCA IN EFFECT FOR FAR NORTHERN WATERS THS MORNING WAS ABLE TO BE 
EXPIRED...AS SEAS FINALLY SAFELY BELOW CRITERIA. NEXT AREA OF LOW 
PRESSURE NOW NOTED OFF THE CAROLINA COAST THIS MORNING. SHOULD BE A 
GENERALLY BENIGN DAY ACROSS THE WATERS TODAY WITH MAINLY LGT NNE 
FLOW TODAY INTO ERY TONIGHT.

BY TONIGHT HOWEVER...CONDITIONS LOOK TO GO DOWNHILL SLOWLY BUT 
STEADILY...AS AN UPPER TROUGH CURRENTLY OVER IN/MI THIS MORNING IS 
FORECAST TO DEEPEN/AMPLIFY...AND TAKE ON AN NEGATIVE TILT AS IT 
PIVOTS TOWARDS THE UPR GRT LAKES BY 12Z FRIDAY. THIS FEATURE WILL 
QUICKLY PUSH A STRONG COLD FRONT ACROSS THE REGION LATE TONIGHT/ERY 
FRIDAY MORNING. HV GONE AHEAD WITH A SCA OVER THE WATERS FROM 02Z 
TONIGHT THROUGH EARLY FRIDAY MORNING. 

FORECAST GETS A BIT TRICKY FOR FRIDAY. ALL MODELS CONTINUE TO DEPICT 
LOW PRESSURE OFF OF HATTERAS THIS MORNING DEEPENING RAPIDLY AS IT 
REACHES THE NEW ENGLAND COAST FRIDAY MORNING. GIVEN WHAT SHOULD BE 
AN INCREASINGLY STRONG PRES GRADIENT AND CAA OVER STILL RELATIVELY 
WARM COASTAL WATERS...THIS SHOULD EASILY YIELD STRONG SCA WNDS 
FRIDAY. CONFIDENCE DEFINITELY HIGH AT THIS TIME THAT LOW-END GALES 
ARE LIKELY FROM FRI AFTN THROUGH EARLY SAT MORNING. 00Z/26NOV NAM 
AND GFS BOTH SHOWING ADEQUATE MOMENTUM XFER AND 925-850 MB WIND 
SPEEDS (~35-45KT BETWEEN 12-15Z FRIDAY AND EARLY SATURDAY 
MORNING...WITH HIGHEST VALUES CLOSER TO THE BOMBING LOW OFF THE 
EASTERN NEW ENGLAND COAST. AT THIS POINT...SCA CONDITIONS ARE A 
SOLID BET FOR ALL WATERS...AND OCCASIONAL TO FREQUENT GUSTS TO GALE 
ALSO APPEAR LIKELY FOR FRIDAY INTO AT LEAST EARLY SATURDAY MORNING. 
HOWEVER...THE EXACT TIMING OF GALES IS PROBLEMATIC AT BEST 3 
FORECAST PERIODS OUT. FOR THIS REASON...PLUS IN LIGHT OF SCA 
CONDITIONS THAT WL HV TO BE DEALT WITH BEFORE THE "RAMP-UP" TO 
GALES...HV DECIDED TO RUN WITH SCA FOR LATE TONIGHT INTO FRIDAY 
MORNING...WITH A LONG-FUSED GALE WATCH THEREAFTER FOR FRIDAY INTO 
SATURDAY. THIS WILL ALLOW DAYCREW THE CHANCE TO BETTER REFINE THE 
EXACT PERIOD OF GALE GUSTS...AND ALSO AFFORDS THE CHC TO EXTEND SCA 
OUT IN TIME IF PROGRESSION OF FRONT IS SLOWER THAN CURRENTLY 
EXPECTED.

GRADIENT RELAXES VERY SLOWLY SATURDAY...AND SCA FOR SEAS WL LIKELY 
BE NEEDED OVER THE COASTAL WATERS INTO LTR SAT AT LEAST. CONDITIONS 
LOOK TO BECOME A BIT MORE BENIGN FOR SUNDAY INTO MONDAY AS FLOW 
LOOKS TO TURN SSW AS HIGH PRESSURE OVER THE SOUTHEAST CONUS BUILDS 
SOUTH OF THE REGION. ANOTHER FRONT APPROACHES FROM THE WEST BY LTR 
MONDAY/TUESDAY.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO NOON EST 
     FRIDAY FOR ANZ630>632.
     GALE WARNING FROM NOON FRIDAY TO 5 AM EST SATURDAY FOR 
     ANZ630>632.
     SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 6 AM EST 
     FRIDAY FOR ANZ633-650-652-654-656-658.
     GALE WARNING FROM 6 AM FRIDAY TO 5 AM EST SATURDAY FOR ANZ633-
     650-652-654-656-658.

&&

$$
SYNOPSIS...BKH
NEAR TERM...BKH
SHORT TERM...BKH
LONG TERM...CCW
AVIATION...JEF
MARINE...CCW