FXUS61 KAKQ 082026
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
326 PM EST TUE DEC 8 2009
.SYNOPSIS...
HIGH PRESSURE WILL RETREAT INTO NEW ENGLAND AND THE CANADIAN
MARITIMES TONIGHT. 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 WEDNESDAY MORNING/...
AS OF 3 PM THIS AFTERNOON...LATEST ANALYSIS SHOWS SURFACE HIGH
PRESSURE RETREATING FROM THE MID ATLANTIC TOWARD NEW ENGLAND.
MEANWHILE A LARGE...VERY POWERFUL STORM SYSTEM CONTINUES MOVING
OUT OF THE ROCKIES AND INTO THE CENTRAL PLAINS...MOVING TOWARD THE
MIDWEST AND GREAT LAKES REGION EARLY WED. THIS SYSTEM WILL LIFT A
WARM FRONT NORTHWARD TOWARD THE MID ATLANTIC THIS
EVENING...FORMING A BAROCLINIC LOW ALONG THE SE COAST
TONIGHT...WHICH WILL MOVE NE ALONG THE SEABOARD THROUGH WED.
ALL MODELS CONTINUE TO SUPPORT ANOTHER WIDESPREAD RAIN EVENT FOR THE
FORECAST AREA. CURRENT REGIONAL RADAR SHOWS A LARGE...GROWING AREA
OF PRECIPITATION UPSTREAM OF THE TN VALLEY...BEGINNING TO AFFECT THE
CAROLINAS AND SOUTHERN VA AS OF 3 PM. RAIN WILL OVERSPREAD THE
FORECAST AREA FROM SW TO NE THIS EVENING. FORECAST SOUNDINGS AND
LOW LEVEL THICKNESSES SUPPORT AN ENTIRELY RAIN EVENT ACROSS THE
FORECAST AREA...THOUGH ACROSS THE FAR NORTHWEST INCLUDING
LOUISA/FLUVANA/GOOCHLAND COULD SEE SOME LIGHT ICE PELLETS MIX IN
EARLY THIS EVENING (AT THE ONSET OF EVENT) AS THE COLUMN
EVAPORTIVELY COOLS AND SURFACE TEMPERATURES HOVER IN THE UPPER 30S
TO NEAR 40. (MAX WET BULB TEMPERATURES ALOFT OF 0 TO -3C)
AGAIN...THIS AREA SHOULD NOT EXPECT MORE THAN A TRACE OF WINTRY
PRECIPITATION AS THE LOW LEVELS ARE QUICK TO BEGIN
MOISTENING/WARMING. TEMPERATURES BEGIN INCREASING AFTER 00Z.
A FLOOD WATCH WAS ISSUED THIS MORNING FOR THE ENTIRE FORECAST AREA.
EVEN THOUGH THIS IS FAIRLY QUICK MOVING SYSTEM...TOTAL QPF AMOUNTS
FOR ENTIRE EVENT (ENDING BY WED AFTERNOON) WILL RUN AROUND 1 TO 2
INCHES...WITH LOCALLY HIGHER AMOUNTS POSSIBLE. GIVEN THE EXTENDED
WET PERIOD OVER THE LAST MONTH OR SO...THIS ADDITIONAL RAINFALL MAY
LEAD TO FLOODING OF SMALL CREEKS...STREAMS AND RIVERS...WHICH ARE
ALREADY RUNNING HIGH IN MANY LOCATIONS...IN ADDITION TO URBAN FLOOD
PRONE AREAS.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
MODELS CONTINUE TO RUN VERY CONSISTENT WITH LARGE SCALE FEATURES
THROUGH MID WEEK. IN THE WAKE OF THE WARM FRONT WED MORNING...WARM
AIR ADVECTION AND MOIST ISENTROPIC LIFT MOVES INTO THE MID ATLANTIC
BETWEEN AN INTENSE LOW PRESSURE SYSTEM OVER THE GREAT LAKES AND A
WEAKER LOW PRESSURE SYSTEM ALONG THE COAST. AGAIN...QPF AMOUNTS ARE
STILL RUNNING 1 TO 2 INCHES TOTAL BY EVENT'S END LATE WED MORNING
(OR AFTERNOON CLOSER TO THE COAST).
BEFORE THE COLD FRONTAL PASSAGE WED AFTERNOON...A FAIRLY STRONG SOUTHERLY
LOW LEVEL JET STREGTHENS EARLY WED MORNING TO 50-60 KTS AT 950
MB...ALLOWING TEMPERATURES TO SURGE EVEN WARMER...ESPECIALLY OVER
THE SE COUNTIES WHERE THIS JET COMBINED WITH WEAK LOW LEVEL
INSTABILITY COULD INITIATE SOME 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 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 ADVECTION. 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 /21Z TUESDAY THROUGH SUNDAY/...
MID AND HIGH LVL CLOUDS COVER THE TAF SITES. RAIN HAS REACHED THE
WRN PORTIONS OF THE CAROLINAS AND WILL CONTINUE SPREADING NE.
AS LOW PRESSURE DEVELOPS THIS EVNG OVER THE CAROLINAS...LOW LEVEL
WINDS WILL INCREASE FROM THE E/SE. THIS WILL BRING INCREASING
AMOUNTS OF LOW LEVEL MOISTURE. CEILINGS WILL LOWER TO IFR OVERNIGHT.
AFT 06Z...TSTMS WILL BE PSBL AT ECG AND DURING THE DAY WED AT ECG
ORF AND PHF. ALSO LLWS WILL NEED TO CONSIDERED AFT 06Z OVER ERN
PORTIONS AS THE NAM BRINGS 70-80 KT WINDS AT 925MB (~2500 FT) OVER
THE ERN SHORE AROUND 12Z. THESE ITEMS MAY BE ADDED TO THE TAFS
WITH FUTURE ISSUANCES.
AS A WARM FRONT LIFTS TO THE NORTH OF OUR AREA...WINDS WILL BECOME
GUSTY FROM THE S/SW. RAIN WILL DIMINISH TO SHOWERS WED MRNG BUT
CEILINGS WILL REMAIN MVFR/IFR THROUGH 18Z.
VFR CONDITIONS WILL RETURN TO ALL SITES AFTR THE PASSAGE OF A COLD
FRONT LATE WED/WED EVNG. HI PRES BUILDS INTO THE MID ATLANTIC STATES
WED NIGHT THROUGH EARLY SAT. THE NEXT IN A SERIES OF WEATHER SYSTEMS
WILL BRING A GOOD CHC OF PCPN AND IFR CONDITIONS TO THE TAF SITES
BEGINNING LATE SAT OR SAT NIGHT.
&&
.MARINE...
SFC HI PRES INVOF NRN WTRS THIS AFTN...RETREATS INTO/THROUGH NEW ENG
TNGT. VIGOROUS STM MVG THROUGH THE PLNS THIS AFTN...TRACKS NE TO THE
LAKES STATES TNGT INTO WED. MNWHL...SCNDRY LO PRES DVLPS INVOF TRPL
PT INVOF INTR SE STATES OVRNGT...AND TRACKS NE THROUGH THE (ERN
PORTION) OF FA WED MRNG. XPCTG SGFNT INCRS IN LLVL E...THEN SSE WNDS
BY LT TNGT...EVENTUALLY SWITCHING TO SW BY MIDDAY/AFTN HRS ON WED.
PTNTL FOR GALE GUSTS LT TNGT (SSE WNDS) AS SCNDRY LO PRES
APPROACHES...THEN AGN MIDDAY/AFTN (SW WNDS). 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.
HOISTING GALES STARTING THIS EVE (WHICH IS WITHIN APPROX 12 HRS OF
PTNTL 35 KT GUSTS)...LASTING THROUGH WED AFTN (CNTRL BAY/SND)...WED
EVE (NR MOUTH OF THE BAY)...AND ON THE OCN (INTO THU AFTN).
&&
.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 THROUGH WEDNESDAY MORNING FOR MDZ021>025.
NC...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR NCZ012>017-030>032-
102.
VA...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR VAZ048-049-060>100.
MARINE...GALE WARNING UNTIL 5 PM EST THURSDAY FOR ANZ650-652-654-656-
658.
GALE WARNING UNTIL MIDNIGHT EST WEDNESDAY NIGHT FOR ANZ632.
GALE WARNING UNTIL 6 PM EST WEDNESDAY FOR ANZ630-631-633.
&&
$$
SYNOPSIS...SMF
NEAR TERM...SMF
SHORT TERM...SMF
LONG TERM...ALB
AVIATION...TMG/LSA
MARINE...ALB
HYDROLOGY...
