FXUS61 KAKQ 090544
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
1244 AM EST WED DEC 9 2009
.SYNOPSIS...
HIGH PRESSURE WILL RETREAT INTO NEW ENGLAND AND THE CANADIAN
MARITIMES OVERNIGHT. WEAK LOW PRESSURE WILL TRACK NORTHEAST ALONG
THE ATLANTIC SEABOARD WEDNESDAY...WHILE A MORE INTENSE LOW
PRESSURE SYSTEM TRACKS ACROSS THE UPPER MIDWEST AND GREAT LAKES
REGION. A COLD FRONT WILL THEN PUSH OFF THE MID ATLANTIC COAST BY
LATE WEDNESDAY NIGHT...AS HIGH PRESSURE BUILDS BACK INTO THE AREA
THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
MODERATE RAIN BEGINNING TO OVERSPREAD THE ENTIRE
REGION...TEMPERATURES HAVE DROPPED OFF INTO THE MID TO UPR 30S
FOR MUCH OF THE I-95 CORRIDOR ON WEST...BUT WITH TEMP/DEW PT
DEPRESSIONS NOW ON THE ORDER OF ONLY A FEW DEGREES...EVAPORATIVE
COOLING PROCESSES SHOULD BE COMING TO AN END. FARTHER
EAST...TEMPERATURES ARE BEGINNING TO RISE A FEW DEGREES...NOW INTO
THE LWR 50S AT ECG/EDE...BUT STILL IN THE 40S ELSEWHERE.
FOR THE OVERNIGHT PERIOD...WILL CONTINUE WITH THE FLOOD
WATCH THROUGH WED MORNING. OVERALL EXPECTING A WIDESPREAD 1 TO 2
INCHES OF RAIN OVER THE NEXT 12 HRS OR SO...AMOUNTS THAT TYPICALLY
WOULD NOT WARRANT THE NEED FOR A FLOOD WATCH...BUT DUE TO THE WET
GROUND FROM RECENT RAINS COULD SEE SOME SPOTTY FLOODING ISSUES BY
WED MRNG ESPECIALLY OVER LOW LYING AREAS...RIVERS AND CREEKS.
TEMPS ARE EXPECTED TO RISE SEVERAL DEGREES LATE/AS WINDS SHIFT TO THE
SSE AFTER 06-09Z...ESPECIALLY OVER SE SECTIONS (AS IS USUALLY THE
CASE TEMPS ACRS THE PIEDMNT WILL BE SLOWER TO RISE AND SHOULD
REMAIN IN THE UPR 30S TO LWR 40S FOR THE BULK OF THE OVERNIGHT
HRS). AS WARM FRONT/CSTL BNDRY MOVES NW FROM THE NC COAST...COULD
POTENTIALLY SEE SOME CONVECTION ACRS THE SE TWDS DAYBREAK.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/...
ONE THING TO CONSIDER ON WED MAY BE A WIND ADVISORY AS 950 MB
WINDS ON BOTH THE GFS AND NAM ARE SHOWING 50-60 KTS. WILL MENTION
THIS POTENTIAL IN THE HWO (BUT HOLD OFF ON A WIND ADSY FOR NOW AS
THERE IS STILL SOME UNCERTAINTY AS TO WHEN THE PRECIP ENDS AND
BETTER MIXING CAN DEVELOP). IN ANY EVENT...ALL AREAS CAN EXPECT
WIND GUSTS OF AT LEAST 35 MPH BY LATE MRNG/ERLY AFTN.
BEFORE THE COLD FRONTAL PASSAGE WED AFTERNOON...TEMPERATURES TO
SURGE EVEN WARMER...ESPECIALLY OVER THE SE COUNTIES WHERE THIS JET
COMBINED WITH WEAK LOW LEVEL INSTABILITY COULD LEAD TO MORE CONVECTION...
MAINLY AROUND AND SOUTH OF I-64. CHANCE OF THUNDERSTORMS FOR THIS
AREA HAS BEEN CONTINUED IN THIS FORECAST ISSUANCE...WITH THE BEST
WINDOW OF OPPORTUNITY BEING WED MORNING MORE THAN THE
AFTERNOON...BEFORE THE COLD FRONT MOVES THROUGH.
HAVE MAINTAINED CATEGORICAL+ POPS WED MORNING OVER THE FORECAST AREA
WITH THE HIGHEST NE AHEAD OF THE COLD FRONT. BY THE LATE MRNG/ERLY
AFTERNOON...RAIN CHANCES WILL DIMINISH SHARPLY FROM SW-NE AS THE
DEEP LAYER DRY SLOT EXPANDS INTO THE FCST AREA.
TEMPERATURES FOR WED CONTINUE TO BE A CHALLENGE...THOUGH THE MODELS
ARE STILL RATHER CONSISTENT WITH THE TIMING OF THE FRONTAL PASSAGE
AND ONSET OF LOW LEVEL COLD AIR ADVECT ION. TEMPERATURES WILL RANGE
FROM THE MID 50S NW TO LOW 70S SE.
HIGH PRESSURE AND MORE QUIET...DRY WEATHER RETURNS FOR THU/FRI.
HIGHS MID 40S/50S LOWS 20S/30S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
LOCKED IN COLDER THAN NRML PTRN THROUGH THE XTNDD PD...W/ A CPL OF
ADDTNL CHCS FOR PCPN. SFC HI PRES STARTS OUT OVR THE RGN FRI
NGT...THEN IS SLO TO WKN/RETREAT ON SAT. XTNDD MDLS CONT TO HV
DIFFICULTY W/ UPCOMING (NRLY) ZNL PTRN (ALOFT) ACRS CONUS. PREFER
SLOER TMG/ARRIVAL (AGN) OF WK SFC LO PRES TRACKING ACRS THE GULF
STATES THROUGH SE CONUS OVR THE WKND. CONTG W/ IDEA OF MSTLY LGT
PCPN PTNTL BRUSHING (MNLY) SRN HALF VA/NE NC - OTRW (BCMG) CLDY.
LATEST/12Z08 GFS HAS SIMILAR IDEA FM YDA...NAEMLY AN AREA OF HIER
QPF MVG ACRS THE NRN PORTION OF VA/MD (ASSOCIATED W/ M/ULVL JET
DYNAMICS)...THOUGH RMN UNCERTAIN ABT THIS PSBL PCPN ATTM. ALSO...NOT
ALL THAT CONFIDENT ABT (QUIK) FCST WRMG (ESP IN LLVLS) SAT INTO SAT
NGT. FAST/ZNL FLO ALOFT AND SHORT TIME FRAME FOR (SGFNT) INCRSD LLVL
FLO FM THE E OR S AS SFC HI RETREATS/SFC LO PRES TRACKS BY TO OUR S.
QUITE PSBL THAT LLVL CAD HANGS TOUGH INLAND...ESP W OF I95 WELL
THROUGHOUT THE PCPN EVENT. LATEST (12Z/08) GFS HAS COLD SNDGS
(AOB 0 DEGS C FM 875MB DN TO SFC) UNTIL AFT MDNGT SAT NGT FOR MUCH
OF INTR SXNS IN VA. WON'T INTRODUCE IP/FRZA INTO FCST ATTM
(HWVR...CERTAINLY SEE PTNTL)...THOUGH WL RETURN TO CHC RA/SN FOR NW
HALF OF FA (FM PCPN ONSET LT SAT MRNG/AFTN INTO SAT NGT). TO THE
SE...CHC RA.
DRYING OUT SUN AFTN...AND RMNG SO MON. YET ANOTHER SYS TRACKS INTO
RGN FM THE WSW BY TUE...HV ADDED LO CHC POPS (RIGHT NOW...RA).
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
WDSPRD IFR CNDTNS IN RAIN AND FOG CONTS THRU 12Z AS OVERRUNNING
PCPN CONTS ACROSS THE RGN. WNDS NOW BCMG GUSTY ACROSS THE SRN TAF
SITES AS WRM FRNT APPRCHS FROM THE S. STRATIFORMED PCPN TAPERS OFF
BY 18Z BUT THEN SCT SHWRS PSBL WITH FROPA DRNG THE AFTRN. ADDED CB
TO SRN TAF SITES WHERE GREATEST INSTAB PROGGED. S-SW WNDS WILL
CONT TO INCRS AS PR-GRDNT TIGHTENS. WNDS XPCTD TO BECOME SUSTAINED
BTWN 15-25 KT WITH GUSTS UP TO 35 KTS AFTR 18Z.
VFR RETURNS TO ALL SITES BY WED EVNG. HI PRES BLDS INTO THE MID
ATLANTIC STATES WED NIGHT THROUGH EARLY SAT. THE NEXT IN A SERIES
OF WEATHER SYSTEMS WL BRING A GOOD CHC OF PCPN AND IFR CONDITIONS
TO THE TAF SITES BEGINNING LATE SAT OR SAT NIGHT.
&&
.MARINE...
GALES UP ACROSS ALL WTRS THRU MOST OF WED. P-GRDNT CONT TO INCRS
NXT FEW HRS WITH WNDS SHFTG INTO SE-S ONCE WRM FRNT LIFTS N. GUSTS
BTWN 30-35 KTS PSBL. BETTER CHCS FOR GALES WED AFTRN AND EVE BEHIND
CDFRNT.
PREVAILING WLY FLO (MOD LLVL CAA) THEREAFTER WED NGT INTO FRI...B4
SFC HI PRES BUILDS OVR WTRS FOR LT FRI INTO SAT. XPCTG ANOTHER PD
OF INCRSD LLVL ONSHR WNDS LT SAT INTO SUN AS SFC LO PRES TRACKS BY
JUST S OF THE WTRS.
&&
.HYDROLOGY...
RIVER FLOOD WARNING FOR THE NOTTOWAY AT SEBRELL REMAINS IN EFFECT
THROUGH MIDWEEK. SEE WBCFLSAKQ FOR DETAILS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...FLOOD WATCH UNTIL NOON EST TODAY FOR MDZ021>025.
NC...FLOOD WATCH UNTIL NOON EST TODAY FOR NCZ012>017-030>032-102.
VA...FLOOD WATCH UNTIL NOON EST TODAY FOR VAZ048-049-060>100.
MARINE...GALE WARNING UNTIL 5 PM EST THURSDAY FOR ANZ650-652-654-656-
658.
GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR ANZ632.
GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ630-631-633.
&&
$$
SYNOPSIS...SMF
NEAR TERM...LKB/SMF
SHORT TERM...SMF
LONG TERM...ALB
AVIATION...MPR
MARINE...ALB/MPR
HYDROLOGY...AKQ
