FXUS61 KAKQ 042056
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
356 PM EST FRI DEC 4 2009

.SYNOPSIS...
LOW PRESSURE OVER THE GULF OF MEXICO THIS EVENING WILL TRACK 
NORTHEAST TO A POSITION OFF THE CAROLINAS BY SATURDAY AFTERNOON.
THE STORM MOVES QUICKLY AWAY FROM THE COAST SATURDAY NIGHT. HIGH
PRESSURE BUILDS BACK OVER THE REGION FOR SUNDAY AND MONDAY. 

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
MSTR FROM DVLPNG CSTL LOW IS QUICKLY MOVG NE ALONG SERN SEABOARD AS
RADAR LOOP PAST FEW HRS HAS SHOWN ECHOES INCRG IN COVERAGE. TSCTNS
SUGGEST THAT IT MAY TAKE SVRL MORE HRS FOR ANY PCPN TO REACH THE
GRND ACROSS AKQ FA...SO HAVE BACKED THE START OF ANY RAIN UNTIL ARND
00Z ACROSS SRN CNTYS. OTW...RAIN QUICKLY OVRSPRDS RGN S-N ACROSS
THE FA TONITE WITH CATEGORICAL POPS (ALL LIQUID) XPCTD ACROSS SRN
HALF OF FA AFTR MIDNITE. POPS INCRG ACROSS THE NRN CNTYS AFTR
MIDNITE... REACHING LRW MD ERN SHORE AFTR 06Z. LOWS DROP INTO TH
U30S ACROSS XTREME NRN CNTYS RANGING TO THE M40S SRN MOST CNTYS.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
MODELS NOW COMING TOGETHER FOR THE FIRST TASTE OF WINTER PCPN ACROSS
THE FA THIS SEASON. CSTL LOW PROGGED TO MOVE RPDLY NE ALONG THE GULF
STREAM WALL SAT THEN INTO VACAPES SAT NITE. UPR LVL NRGY MOVG ACROSS
THE MTS THEN CSTL PLAIN WILL AID TO ENHANCE PCPN CHC SAT AFTRN AND
EVE. AS THE CSTL LOW DEEPENS...IT WILL PULL IN COLDER AIR NW-SE SAT
AFTRN AND EVE. THIS RESULTS IN P-TYPE CONCERNS AS CRITICAL THICKNESS
VALUES CRASH TOWARD THE COAST BTWN 18Z-03Z SUN. UPSHOT WILL BE A COLD
RAIN ERLY. RAIN WILL THEN MIX WITH THEN CHANGE TO WET SNOW DRNG THE
MORNING AND ERLY AFTRN HRS ACROSS NW CNTYS. THIS TREND WILL CONT SEWD
THRU THE AFTRN AS COLUMN CONTS TO COOL. FCST CHALLENGE EVEN LESS THAN
24 HRS OUT IS SFC TMPS AND WHETHER ANY SNOW WILL ACCUMULATE.

AFTR COORD WITH RNK/LWX...CONFIDENCE HIGH ENUF TO GO WITH A WNTR WX
ADVSRY FOR LOUISA/FLUVANNA CNTYS SAT AFTRN AND EVE (1-2 INCHES). THESE
WILL BE THE AREAS WHERE TMPS FALL TO NR 32 THE QUICKEST AS WELL AS
HAVING ENUF QPF FOR THE SNOW TO ACCUMULATE. WILL CARRY ABOUT A ONE
COUNTY BUFFER AREA ARND THE ADVSRY FOR UP TO ONE INCH OF SNOW ACCUM
(CAROLINE/HANOVER/GOOCHLAND/POWHATAN/CUMBERLAND CNTYS). APPEARS TMPS
DRNG THE DAYLIGHT HRS WILL PREVENT ANY SGNFCNT ACCUMULATIONS FRTHR
S&E TOWARD THE RIC METRO AREA (BASICALLY LTL OR NO ACCUM). TMPS SLOWLY
FALL THRU THE 30S MOST AREAS...REMAINING 40-45 SE. TOTAL QPF FOR
THE EVENT WILL RANGE BTWN .25-.50 WITH MOST OF IT BEING LIQUID.

CHANGEOVR LINE CONTS TO TRACK TOWARD THE COAST SAT EVE...BUT PCPN 
PROGGED TO PULL E AS WELL. MODELS NOW SHOWING SOME WRAPARND PCPN
ACROSS LWR MD AND VA ERN SHORE AREAS THRU ERLY MORN HRS. THIS WILL
LIKELY CHANGE OVR TO ALL SNOW B4 ENDING AS WELL. THE RAIN MAY END
AS A RAIN/SNOW MIX EVEN ACROSS TIDEWATER/NE CORNER OF NC AS CAA
DROP TMPS INTO THE M30S. OTW...PCPN ENDS W-E AFTR MIDNITE WITH A
GRDL DCRS IN CLDNS. TMPS DROP INTO THE 20S W OF THE BAY...L-M30S
SERN AREAS. 

HI PRES BUILDS OVR THE FA SUN...BRINGING DRY BUT COLD CNDTNS. LWRD
MAX TMPS ABT A CATEGORY DUE TO CONT CAA AS WELL AS ANY SNOW THAT
REMAINS. HIGHS 40-45. CLDS FROM NXT SRN STREAM S/W APPRCH LATE SUN
NITE. LOWS M20S-M30S. NOT MUCH MSTR FOR THE S/W TO WORK WITH ON
MONDAY...SO WILL KEEP IT DRY BUT M CLDY. HIGHS M40S- L50S.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
GENERAL MODEL AGREEMENT IN THE EXTENDED RANGE CONTINUES AS THE MODELS
SHOW A FAST FLOW ACROSS THE US WITH MUCH MORE PACIFIC FLOW VERSUS
A MERIDIONAL FLOW. THIS WILL RESULT IN RELATIVELY MILD WEATHER FOR
THIS TIME OF YEAR...BUT WILL SEE SEVERAL SYSTEMS MOVING ACROSS THE
US WITH GULF MOISTURE AVAILABLE.

TO BEGIN THE PERIOD...AS NORTHERN STREAM ENERGY RACES OUT OF THE 
NORTHERN PLAINS INTO NEW ENGLAND TO BEGIN THE PERIOD...QUASI ZONAL 
FLOW ALOFT SHOULD ALLOW FOR A GENERALLY DRY FIRST HALF OF THE 
UPCOMING WEEK. DID ALLOW FOR A QUICK SLIGHT CHC POP MONDAY NGT IN 
ASSN WITH A QUICK MOVING SOUTHERN STREAM S/W. OTW...MAINLY DRY 
TIMEFRAME FOR MONDAY NIGHT/TUESDAY

BY LTR TUESDAY/WEDNESDAY...DEEP LOW PRESSURE EMERGES FROM THE 
CENTRAL ROCKIES AND PUSHES ACROSS THE CENTRAL/SOUTHERN PLAINS...AND 
EVENTUALLY PUSHING NE INTO THE EASTERN GRT LKS/NEW ENGLAND BY LATE 
IN THE PERIOD. THIS WL TURN FLOW ALOFT MORE SW DOWNSTREAM ACROSS THE 
EASTERN CONUS...ALLOWING BUILDING MOISTURE/CLOUDS LTR TUESDAY...WITH 
INCREASED CHCS FOR OVERRUNNING RAIN ON TUESDAY NIGHT INTO WEDNESDAY.
 
THE GFS AND ECMWF BOTH SHOW A STRONG TROUGH SWEEPING EAST WITH THIS 
SYSTEM ON WEDNESDAY. THE GFS IS MORE AMPLIFIED AND AS A RESULT 
PUSHES MUCH WARMER AIR INTO THE REGION WEDNESDAY. THE ECMWF IS NOT 
AS AGGRESSIVE...NOT AMPLIFYING THE WAVE UNTIL AFTER IT REACHES NEW 
ENGLAND SO THE WARMING IS NOT A GREAT. FOR NOW HAVE CONTINUED TREND 
TO INCREASE POPS TO HIGH CHANCE AND HELD TEMPERATURES DOWN CLOSER TO 
THE ECMWF/HPC NUMBERS. AS PREV SHIFT NOTED...IF THE PATTERN DOES 
AMPLIFY AS QUICKLY AS THE GFS DEPICTS...IT COULD EASILY ALLOW 
TEMPERATURES TO PUSH INTO THE 60S PRIOR TO THE COLD FRONTAL PASSAGE.

BY THURSDAY...THE LOW IS DEEPENING OFF THE NEW ENGLAND COAST WITH
A COLD NW FLOW ACROSS THE MID ATLANTIC STATES. THIS SHOULD ALLOW
FOR CLEARING CONDITIONS WITH COOL...BUT NOT COLD TEMPERATURES.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
VFR CONDS CONTINUE THIS AFTN AS MID/HIGH CLDS ARE BEGINNING TO MV
ACRS THE RGN. EXPECT CIGS TO REMAIN ABOVE 5K FT INTO THE EVNG
BEFORE BEGINNING TO DROP AS ONSHORE FLOW AHEAD OF A DVLPNG CSTL
SYSTEM SATURATES THE LOWER LEVELS. WNDS WL REMAIN N TO NE AROUND
10 KT OR LESS OVERNIGHT...EXCEPT FOR THE SRN CSTL SITES
(ORF/PHF/ECG) WHICH WL SEE AN INCREASE TO 10 TO 15 KT SUSTAINED
WITH GUSTS AROUND 20 KT BY EARLY SAT MRNG. PCPN SHOULD BEGIN ACRS
SRN SITES BY LATE EVNG THEN MV NWD. LOOK FOR MVFR ACRS MOST OF THE
RGN BY 09Z WITH POSSIBLE IFR AROUND SUNRISE SAT.

THE CSTL SYS MVS NEWD OFF THE CAROLINAS SAT BRINGING GUSTY
WNDS...MAINLY ALONG THE CST. AS FOR PRECIP TYPE...EXPECT TO SEE
RAIN THROUGH THE MRNG SAT. FROM NOON ONWARD...RAIN COULD MIX WITH
AND/OR CHANGE TO SNOW LATER IN THE AFTN/AFTER 20Z FOR RIC...AND
FOR ORF/PHF/SBY AFTER 00Z/SUNDAY. CLEARING BY SUNDAY MORNING
BETWEEN 06-12Z. DRIER CONDS INSTORE FOR BEGINNING OF NEXT WEEK.
THE NEXT SIGNIFICANT CHC OF PCPN LOOKS TO BE WED.

&&

.MARINE...
RELATIVELY BENIGN CONDITIONS ACROSS THE WATERS THIS AFTN INTO ERY 
THIS EVENING...ENE WNDS 10-15KT. 

WNDS/WAVES LOOK TO BACK TO THE NNE AND RAMP UP LATER ON TONIGHT INTO 
SATURDAY...AS A DEVELOPING COASTAL LOW CURRENTLY OVER THE EASTERN 
GULF COAST PUSHES TO A POSITION JUST OFF THE SC/NC COAST LATER 
TONIGHT. THIS FEATURE WL PUSH NORTHEAST AND STRENGTHEN JUST OFF THE 
MID-ATLANTIC COAST DURING THE DAY SATURDAY...BEFORE PUSHING WELL 
NORTHEAST OF THE AREA INTO SUNDAY. 

UNLIKE THE LAST EVENT...THIS WILL FEATURE A NORTHERLY FLOW AND MUCH 
BETTER MIXING SO EVEN WITH A MORE MODEST SFC PRESSURE 
GRADIENT...THERE IS STILL THE POTENTIAL FOR GALES. BOTH 12Z/4DEC 
NAM/GFS H92-85 YIELD 35-40KT WNDS BY 18Z SATURDAY...WITH BUFKIT DATA 
SHOWING ENOUGH MOMENTUM XFER TO YIELD LOW END GALE GUSTS SATURDAY 
AFTN. AS A RESULT...AFTER COORDINATION WITH NEIGHBORING OFFICES AND 
TO AVOID A CONFUSING RAMP-UP TO GALES...WL GO AHEAD WITH GALE 
WARNING OVER NORTHERN COASTAL WATERS FOR SATURDAY. DO EXPECT A 
PERIOD OF LOWER SCA WNDS DURING SATURDAY MORNING AHEAD OF THE 
COASTAL LOW...WITH GOOD CHANCE OF STRONG SCA WNDS AND LOW END GALE 
GUSTS OVER NORTHERN WATERS SAT AFTN AND ESP SAT NIGHT. ELSEWHERE..WL 
CONTINUE WITH SMALL CRAFT ADVISORIES FOR CHES BAY AND SOUTHERN 
WATERS LATE TONIGHT THROUGH EARLY SUNDAY...THOUGH LATER SHIFTS WL 
HAVE TO KEEP AN EYE ON POTENTIAL FOR GALE GUSTS IN CAA BEHIND THE 
DEPARTING LOW. FOLLOWED CLOSER TO A LESS AGGRESSIVE NAM/SREF BLEND 
FOR WINDS SAT NIGHT/EARLY SUNDAY...AS DEEP LYR CAA SHOULD CONTINUE 
TO BRING 25KT OR MORE TO THE RELATIVELY WARM WATERS (GFS APPEARS TOO 
FAST AT DIMINISHING THE WINDS). 

WINDS TURN MORE TO THE NNW LTR TOMORROW NIGHT/ERY SUN...SO 
SEAS/TIDAL ANOMALIES DO NOT HAVE A LOT OF TIME TO BUILD (ALTHOUGH 
SEAS OF AT LEAST 8-10 FT ARE STILL EXPECTED). HV HELD OFF ON HIGH 
SURF ADVISORY FOR NOW...BUT SWAN/WW3 BOTH INDICATE THAT ONE MAY BE 
NEEDED TOMORROW NIGHT/SUNDAY. 

HIGH PRESSURE BUILDS IN LATER SUNDAY/MONDAY ALLOWING SEAS/WINDS TO 
SUBSIDE....WITH MORE BENIGN CONDITIONS ACROSS THE WATERS FOR THE 
FIRST HALF OF NEXT WEEK.

&&

.HYDROLOGY...
DUE TO RECENT HEAVY RAINFALL OVER THE REGION...FLOOD WARNINGS
CONTINUE FOR THE MEHERRIN RIVER AT LAWRENCEVILLE AND THE NOTTOWAY
RIVER NEAR STONY CREEK. SEE LATEST WBCFLSAKQ FOR MORE INFO.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...WINTER WEATHER ADVISORY FROM NOON TO 10 PM EST SATURDAY FOR 
     VAZ048-049.
MARINE...SMALL CRAFT ADVISORY FROM 1 AM SATURDAY TO NOON EST SUNDAY FOR 
     ANZ632-633-656-658.
     SMALL CRAFT ADVISORY FROM 4 AM SATURDAY TO NOON EST SUNDAY FOR 
     ANZ630-631.
     GALE WARNING FROM 6 AM SATURDAY TO 5 AM EST SUNDAY FOR ANZ650-
     652-654.

&&

$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...MPR
LONG TERM...MAM
AVIATION...AM
MARINE...MAM
HYDROLOGY...AKQ