FXUS61 KAKQ 050815
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
315 AM EST SAT DEC 5 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 THIS 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 THIS 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 /08Z SATURDAY THROUGH WEDNESDAY/...
RADAR SHOWS PRECIP MOVG INTO SE VA 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 EXPECTED
TO OCCUR BY LATE AFTN INTO EVENING HRS FROM RIC 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...
ALL MODELS AGREE ON DEVELOPING LOW OFF THE CAROLINA COAST TODAY.
TIMING OF INCREASE IN WINDS WITH THIS DEVELOPMENT SYSTEM WILL
FOLLOW SREF GUIDANCE. LOOKING AT THE 925 MB LEVEL SEE THE MAIN
INCREASE IN WINDS DEVELOPING THIS AFTERNOON AND TONIGHT. THIS
MEANS THE STRONGEST WINDS WILL DEVELOP WHEN THE WINDS TURN MORE
NORTHERLY TO NORTHWEST. SREF GUIDANCE TONIGHT SHOWS HIGH
PROBABILITY OF SCA WINDS OVER ALL WATERS BUT KEYS IN ON NE COASTAL
WATERS FOR THE BEST CHANCE OF GALE. MAIN THREAT OF GALE WILL BE
FROM WIND GUSTS. USED A GUST FACTOR OVER ATER BETWEEN 1.2 AND 1.3.
THIS CORRESPONDS TO RESEARCH PRESENTED AT THE NWA MEETING. THIS
JUST BARELY BRINGS GALES TO NRN WATERS. BY LATE TONIGHT AND INTO
SUN AS HIGH PRESSURE MOVES IN WINDS WILL QUICKLY SUBSIDE BELOW SCA.

WINDS TURN MORE TO THE NNW LTR TONIGHT/ERY SUN...SO SEAS/TIDAL
ANOMALIES DO NOT HAVE A LOT OF TIME TO BUILD (ALTHOUGH SEAS OF AT
LEAST 7-9 FT ARE STILL EXPECTED). HV HELD OFF ON HIGH SURF
ADVISORY FOR NOW.

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 TODAY TO 10 PM EST THIS 
     EVENING FOR VAZ048-049.
MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST SUNDAY FOR ANZ632-633-656-
     658.
     SMALL CRAFT ADVISORY UNTIL NOON EST SUNDAY FOR ANZ630-631.
     GALE WARNING UNTIL 5 AM EST SUNDAY FOR ANZ650-652-654.

&&

$$
SYNOPSIS...MPR
NEAR TERM...MPR/CCW
SHORT TERM...MPR
LONG TERM...MAM
AVIATION...JAB/JEF
MARINE...JAB
HYDROLOGY...