416
FXUS61 KAKQ 210512
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
1212 AM EST SAT NOV 21 2009
SYNOPSIS
HIGH PRESSURE SETTLES OVER THE AREA TONIGHT AND LINGERS THROUGH
SATURDAY NIGHT. THE AN AREA OF LOW PRESSURE MOVES THROUGH THE GULF
COAST AND UP THE EASTERN SEABOARD FROM LATE SUNDAY THROUGH MONDAY
NIGHT. HIGH PRESSURE BUILDS DOWN THE EASTERN SEABOARD ON TUESDAY
INTO WEDNESDAY.
NEAR TERM /THROUGH TODAY/
LATEST WX ANALYSIS DEPICTS SFC HIGH PRESSURE OVER THE MIDWEST
THIS EVENING. TO THE SOUTH...DEVELOPING LOW PRESSURE NOTED OVER
THE WESTERN/CENTRAL GULF COASTS THIS EVENING IN ASSN WITH
MID/UPPER LVL LOW OVER WEST CENTRAL TEXAS. SOME CIRRUS ASSOCIATED
WITH THIS FEATURE GETTING SHOVED DOWNSTREAM...RIDING SW FLOW ALOFT
ALREADY PUSHING ACROSS THE MID-SOUTH AND CAROLINA PIEDMONT...AS
NOTED ON EARLY EVENING IR/RAMSDIS WV IMAGERY. WL LKLY SEE THESE
HIGH CLOUDS CONTINUE TO MAKE INROADS ACROSS THE WESTERN HALF OF
THE AREA INTO THE OVERNIGHT HRS.
OTHERWISE...SURFACE HIGH PRESSURE SETTLES OVER THE REGION OVERNIGHT
AND BEGINS TO SLIDE OFF TO THE NE ON SATURDAY. SHOULD SEE MAINLY
CLR CONDITIONS OVER THE EASTERN CWA. HOWEVER...WITH THE AFOREMENTIONED
SW FLOW ALOFT AHEAD OF THE NEXT SYSTEM...SHOULD BEGIN TO SEE
CIRRUS ACROSS THE WESTERN...AND EVENTUALLY THE CENTRAL CWA
OVERNIGHT. STAYED CLOSE TO INHERITED TEMPS...AND STILL SHUD SEE
GOOD RADIATIVE CONDITIONS. ERY MORNING LOWS IN THE MID 30S TO THE
NR 40...WITH THE POTENTIAL FOR SOME L30S WELL NORTH/NW OF RIC.
SATURDAY...
SHOULD SEE DECENT WARMING FOR SATURDAY. HAVE GONE WITH THE WARMER
MAV GUIDANCE...ALTHOUGH THE THICKEN CLOUDS COULD HOLD TEMPS DOWN A
DEGREE OR TWO MAINLY IN W/SW PARTS OF THE CWA. SEASONABLE HIGHS IN
THE L60S FOR MOST ZONES...UPR 50S OVER THE EASTERN SHR.
SHORT TERM /TONIGHT THROUGH MONDAY/
ACTIVE PERIOD BEGINS ON SUNDAY INTO MONDAY...BUT THE MODELS ARE
NOT IN VERY GOOD AGREEMENT. THE GFS SEEMS TO BE TOO STRONG AND TOO
FAST WITH THE SYSTEM AND IS GENERALLY THE ONLY MODEL SHOWING THIS
STRONG OF A SYSTEM. THE NAM/CANADIAN SEEM TO BE THE MIDDLE OF THE
ROAD WITH THE CLOUDS INCREASING ON SUNDAY WITH THE BULK OF THE
OVERRUNNING PCPN ON SUNDAY NIGHT THROUGH MONDAY. THE 12Z ECMWF IS
EVEN SLOWER...AND HAS TRENDED SLOWER FROM THE 00Z RUN. FOR NOW
HAVE GONE TOWARD THE MIDDLE OF THE GUIDANCE...INCREASING CLOUDS
AND BRINGING SOME LOW POPS IN LATE SUNDAY BUT FOCUSING POPS AND
QPF ON SUNDAY NIGHT INTO MONDAY. HESITANT TO BE TOO SLOW AS
OVERRUNNING IS OFTEN FASTER THAN WHAT THE MODELS INDICATE.
FOR TEMPERATURES...HAVE GONE CLOSER TO THE MET ON SUNDAY FOR
HIGHS...BUT NOT AS WARM GIVEN THE INCREASING CLOUDS. FOR SUNDAY
NIGHT DID LEAN A LITTLE MILDER GIVEN THE EXPECTED INCREASE IN
MOISTURE. HAVE LOWERED HIGHS ON MONDAY GIVEN THE EXPECTED CLOUDS
AND LINGERING RAIN. THE MEX NUMBERS LOOK TOO WARM ON MONDAY...BUT
GIVEN THE SPEED OF THE GFS SOLUTION...IT IS UNDERSTANDABLE THEY
WOULD BE WARMER.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
LOW CONFIDENCE FCST FOR THIS PERIOD AS GFS/NAM/ECMWF SHOWING
RATHER LARGE DIFFERENCES EVEN IN THE SHORT TERM...SO EVOLUTION OF
NEXT SYSTEM LATER IN THE WEEK VERY UNCERTAIN. WILL KEEP CHC POPS
IN THE FCST MON NIGHT AS NE FLOW CONTINUES WITH SFC HIGH OFF THE
NEW ENGLAND COAST...AND AT LEAST A WAVE OF LOW PRESSURE OFF THE
MID ATLC/SE COAST (OUTLIER GFS SOLN GNLY DISREGARDED). FOR
TUE/WED...RIDGING DEVELOPS EITHER ALONG THE E COAST (ECMWF) OR
WELL OFF THE COAST (GFS). GNLY KEEPING SKIES PTLY CLOUDY FOR THIS
PERIOD WITH NEAR TO SLIGHTLY ABOVE AVG TEMPS...HIGHS INTO LWR 60S
AND LOWS MAINLY IN THE 40S. AS THE RIDGE BREAKS DOWN ON
THANKSGIVING DAY...GFS/ECMWF BRING NEXT SYSTEM INTO THE AREA FROM
THE SOUTH (ALTHOUGH AGAIN W/ MAJOR DIFFERENCES IN TRACK). BRING
INCREASING CLOUDS INTO THE FCST...ALONG WITH AT LEAST A SLGT CHC
FOR SHWRS. FRONT LOOKS TO PUSH THROUGH BY FRI...DRIER AND COOLER
WX FOR FRI.
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
VFR CNDTNS XPCTD THRU FCST PRD XCPT FOR SOME MVFR CNDTNS THRU 12Z
IN PTCHY FOG. WENT AHEAD WITH A BKN250 FCST VICE SKC AS SAT LOOP
ALRDY INDCTG PLNTY OF CI APPRCHG FROM SW.
LOW APPRCHS FROM S BY LATE SUN WITH NXT CHC FOR LWR CIGS AND CHANCE
FOR RAIN INTO MON. THE WEATHER IMPROVES AGAIN BY TUE.
MARINE
CONT SCA FOR NC CSTL WTRS FROM VA/NC BORDER TO CURR BCH LGT TIL 6
AM SAT AS NE WNDS KEEPS SEAS ARND 5 FT.
SFC HIGH MOVES OFF TO THE NE...AND A WAVE OF LOW PRS APPRCHS FROM
THE S ON SUN. GFS SOLN LOOKS TOO FAST AND HAVE DISREGARDED THE
SOUTHERLY FLOW REGIME IT DEPICTS ON MONDAY (KEEPING WINDS NE ON
MON/MON NGT PER NAM/UKMET/ECMWF CONSENSUS). THIS CONSENSUS SOLN
PLACES THE SFC HIGH IN A FAVORABLE POSITION FOR SCA CONDITIONS
LATER SUNDAY THROUGH MONDAY (OVER NEW ENGLAND) AND HAVE GONE CLOSE
TO PREV FCST (HIGHER THAN THE MODELS FOR WIND SPEEDS). FOR
SEAS...GNLY WENT 5-6 FT FOR NOW ON THE COAST (GFS SOLN YIELDS A
WAVEWATCH FCST FOR ONLY 4-5 FT SOUTH AND 6-7 FT NORTH).
AKQ WATCHES/WARNINGS/ADVISORIES
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
ANZ658.
SYNOPSIS...ESS/MAM
NEAR TERM...ESS/MAM
SHORT TERM...ESS
LONG TERM...LKB
AVIATION...MPR
MARINE...LKB/MPR
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