FXUS61 KAKQ 050341
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
1041 PM EST FRI DEC 4 2009
.SYNOPSIS...
LOW PRESSURE OVER THE GULF OF MEXICO 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/...
SATURATION CONTINUES TO SLOWLY DVLP AT LOW LVLS WITH VERY
-RA/SPRINKLES STARTING TO NOSE CLOSER TO THE THE CWA FROM THE
SOUTH WITH INITIAL H70 OMEGA FIELD. RAIN WILL OVERSPREAD THE SRN
HALF OF THE CWA FROM 06-09Z AS H92 RH FIELDS INCREASE TO AOA 90
PERCENT FROM FVX/RIC/WAL LINE. FURTHER NORTH LIGHT -RA OVRNT WILL
INCREASE TWRDS DAYBREAK OR SOON AFTER THAT. COULD EVEN SEE SOME
LIGHT -SN TO MIX IN WITH -RA FAR WNW BY 12Z AS FREEZING LVLS
START TO FALL (BUT SHOULD MELT ON CONTACT W/SFC UNTIL LATER IN
THE MORNING).
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 /04Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDS AT 10 PM TONIGHT BUT CLOUDS CONT TO THICKEN OVER THE
REGION IN ADVANCE OF LOW PRES SYS TO THE SOUTH. RADAR SHOWS PRECIP
MOVG INTO NE NC AND SPREADING STEADILY TO THE NORTH. EXPECT CIGS
TO DROP INTO MVFR CONDS BEFORE SUNRISE AS RAIN OVERSPREADS AREA.
WNDS WILL BE NE AROUND 10 KT THRU THE NIGHT BUT SOME GUSTINESS MAY
OCCUR ALONG COASTAL AREAS. WNDS WILL INCREASE ALONG COASTL
SECTIONS AS LOW MOVES OFF COAST OF NC WITH GUSTS TO AROUND 25 KT
PSBL. CIGS WILL GENLY LOWER TO IFR CONDS AFT SUNRISE AS RAIN
INCREASES. A CHANGEOVER FROM RAIN TO RAIN/SNOW MIXED AND PSBL ICE
PELLETS EXPECTED TO OCCUR BY LATE AFTN INTO EVENING HRS FROM RIC
TO PHF TO SBY. AREAS CLOSEST TO COAST LIKELY TO REMAIN MOSTLY RAIN
ALTHOUGH SLIGHT CHC OF RAIN/SNOW MIXED STILL PSBL AROUND SUNSET.
CLEARING LATE SAT NIGHT/SUN AM AS LOW MOVES FARTHER NORTH AND HI
PRES BUILD IN FOR SUN. THE NEXT SIGNIFICANT CHC OF PCPN LOOKS TO
BE WED.
&&
.MARINE...
RELATIVELY BENIGN CONDITIONS ACROSS THE WATERS TONIGHT WITH NE
WNDS 10-15 KT OR LESS. WNDS EXPECTED TO GRADUALLY INCREASE TONIGHT
ESPECIALLY AFTER MIDNIGHT AS LOW PRES SYS APPROACHES AND DEVELOPS
ALONG THE SC/NC COAST.
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 UNTIL 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/CCW
SHORT TERM...MPR
LONG TERM...MAM
AVIATION...AM/JEF
MARINE...MAM/JEF
HYDROLOGY...CCW
