FXUS61 KAKQ 091627
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
1127 AM EST WED DEC 9 2009
.SYNOPSIS...
A STRONG AREA OF LOW PRESSURE SLOWLY TRACKS ACROSS THE UPPER
MIDWEST AND GREAT LAKES REGION TODAY. THE ASSOCIATED COLD FRONT
MOVES OFF THE MID ATLANTIC COAST BY LATE TONIGHT. HIGH PRESSURE
BUILDS BACK INTO THE AREA THURSDAY AND FRIDAY. ANOTHER LOW
PRESSURE SYSTEM PASSES BY SOUTH OF THE MID ATLANTIC WATERS OVER
THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
LAST BAND OF RAIN EXITING THE COAST AT THIS TIME...BUT THE COLD
FRONT REMAINS WELL TO THE WEST. IT SHOULD CROSS THE MOUNTAINS
AROUND 18Z AND SWING ACROSS EASTERN VA BETWEEN 00Z AND 03Z
THURSDAY. AHEAD OF THE FRONT...SEEING CLOUDS BREAKING UP...EXCEPT
IN FAR WESTERN PART OF CWA...WERE WEAK LOW LEVEL INVERSION HAS
TRAPPED LOW LEVEL MOISTURE. ONCE THE MIXING BEGINS TO
INCREASE...SHOULD SEE THESE CLOUDS ERODE AND SOME LATE DAY SUN
POSSIBLE THERE. OTHER LOCATIONS SHOULD SEE THE SUN LATE THIS
MORNING INTO THE EARLY AFTERNOON. AS THE FRONT APPROACHES LATE IN
THE DAY...SOME LOW TO MID LEVEL MOISTURE WILL GET DRAW BACK INTO
THE REGION FROM THE SOUTH. WHILE NO ADDITIONAL HEAVY RAIN IS
EXPECTED...A FEW ISOLATED TO SCATTERED SHOWERS COULD FORM IN
ADVANCE OF THE FRONT. FOR TEMPERATURES...ONCE THE SUN COMES UP
SHOULD SEE A GOOD SPIKE UPWARD AS THE 850 MB TEMPERATURES ARE
STILL QUITE WARM. HOWEVER...IN THE FAR WEST WHERE THE CLOUDS ARE
LINGERING...EXPECT TEMPERATURES TO CLIMB IN A SLOWER
FASHION...STRUGGLING TO REACH THE LOW 50S FOR HIGHS.
FOR TONIGHT ONCE THE FRONT CLEARS...THE FLOW ALOFT IN THE LOW
LEVELS TURNS NW SO SHOULD SEE SOME CLEARING WITH A GRADUAL WEAKEN
OF THE WINDS. BUT THE FLOW AT HIGH LEVELS REMAINS SW SO SOME
HIGHER CLOUDS SHOULD INCREASE AFTER MIDNIGHT.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
MINIMAL CHANGES MADE TO THE PREVIOUS FCSTS DURING THIS PERIOD...AS
HIGH PRESSURE BRINGS MORE TRANQUIL (DRY) WX AND SEASONABLE TEMPS
TO THE REGION. LOWS TONIGHT WILL BE DRIVEN MAINLY FROM THE
CONTINUED POST-FRONTAL LLVL COLD ADVECTION (I.E. SFC WINDS STAYING
UP A BIT WILL LIMIT THE RADIATIONAL COOLING). THEREFORE EXPECT A
MORE UNIFORM DISTRIBUTION WITH TEMPS...WITH LOW-MID 30S NW TO LOW-
MD 40S SE.
DRY AND PROGRESSIVELY COOLER THU INTO FRI AS THE SFC HIGH CENTER
DRAWS CLOSER TO THE MID ATLC REGION (AND DAYTIME VERTICAL MIXING
BECOMES MORE SHALLOW. HIGHS MID 40S FAR N TO MID 50S FAR S ON THU...
COOLER THU NIGHT (LIGHTER SFC WINDS) WITH MINS MAINLY THROUGH THE
20S. HIGHS FRI 40-45 OVER THE BULK OF THE REGION...WITH READINGS
PSBLY NOT GETTING OUT OF THE 30S OVER THE LWR MD ERN SHORE.
&&
.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 /16Z WEDNESDAY THROUGH SUNDAY/...
IFR/MVFR CNDTNS IN RAIN AND FOG CONTS NXT SVRL HRS AS SCND BATCH
OF PCPN MOVES ACROSS THE RGN. GUSTY WNDS ALONG THE COAST ATTM. CONT
WITH CB TO SRN TAF SITES WHERE GREATEST INSTAB PROGGED. S-SW WNDS
INCRS AS PRS-GRDNT TIGHTENS. WNDS XPCTD TO BECOME SUSTAINED BTWN
15-25 KT WITH GUSTS UP TO 35 KTS.
VFR RETURNS TO ALL SITES BY THIS 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...
ZIPPER LOW HAS MOVE OFFSHORE INTO THE VACAPES ERLY THIS AM. THE
PASSAGE OF THIS FTR HAS (OR SHORTLY WILL) SWITCH THE FLOW TO A SW
DRCTN THIS AM. STRNG ADVCTN CONTS THIS AFTRN ACROSS THE CHES BAY
RGN AND THRU MOST OF THE NITE ALONG THE CSTL WTRS. THUS...GALE
HEADLINES REMAIN IN PLACE THRU THE DAY. GALES SHUD BE REPLACED BY
STRNG SCA'S ACROSS THE CHES BAY AND CURRITUCK SND AREAS TONITE.
WESTERLY FLOW CONTS INTO FRI B4 SFC HIGH PRES BUILDS OVR WTRS FOR LT
FRI INTO SAT. SCA ALONG CSTL WTRS FOR SEAS WILL LIKELY CONT INTO FRI
AS WELL. ANOTHER PD OF INCRSD LLVL ONSHR WNDS XPCTD LT SAT INTO SUN
AS NEXT SFC LOW 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. WILL HAVE TO ASSESS
THE IMPACTS OF THIS RECENT BOUT OF RAINFALL LATER TODAY...PER
COORDINATION WITH RFC'S AND THEIR LATEST RIVER MODEL FCSTS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR ANZ632.
GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ633.
SMALL CRAFT ADVISORY UNTIL 1 PM EST THURSDAY FOR ANZ630-631.
GALE WARNING UNTIL 5 PM EST THURSDAY FOR ANZ650-652-654-656-
658.
&&
$$
SYNOPSIS...BKH
NEAR TERM...ESS
SHORT TERM...BKH/SMF
LONG TERM...ALB
AVIATION...MPR
MARINE...MPR
HYDROLOGY...
