FXUS61 KAKQ 120837
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
337 AM EST SAT DEC 12 2009
.SYNOPSIS...
HIGH PRESSURE MOVES OFF THE MID ATLANTIC COAST LATER TODAY. LOW
PRESSURE ALONG THE CAROLINA COAST TONIGHT TRACKS NORTHEAST EXITING
THE MID ATLANTIC COAST SUNDAY NIGHT AND MONDAY. HIGH PRESSURE BUILDS
INTO THE AREA MONDAY. ANOTHER QUICK MOVING COLD FRONT ARRIVES ON
TUESDAY WITH COLDER AIR ARRIVING FOR THE SECOND HALF OF THE WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
CORE OF SFC HIGH OVRHD ATTM. RIDGE AXIS SHIFTS OFFSHORE WITH RETURN
(S-SW) FLOW DVLPNG THIS AFTRN. TSCTNS INDCT HIGH LVL MSTR OVRSPRDS
FA S-N. H85 TMPS BEGIN TO WRM SLOWLY TDY (TO ARND -3C). GIVEN YSTRDYS
HIGH TMPS WERE BLO FCSTD READINGS...WILL LEAN TOWARD THE COLDER NAM
GUID FOR HIGHS (L-M40S).
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
THE MODELS CONT IN GNRL AGREEMENT WRT SRN STREAM SYSTM BUT LEANED
TOWARD A SREF SOLN WHICH SEEMS TO BE A COMP BTWN NAM/GFS. DECENT
WAA PCPN EVENT SETTING UP LATE TONITE AND SUN. CHALLENGING PART OF
THIS FCST CONTS TO BE P-TYPE AT ONSET AS INITIAL AIRMASS WILL BE
QUITE DRY RESULTING IN SOME EVAPORATIVE COOING. MODELS RPDLY MOVE
MSTR IN STARTING LATE THIS EVE ACROSS SWRN CNTYS BUT NOT REACHING
THE LWR MD ERN SHORE UNTIL ARND 12Z SUN. STILL LOOKING AT A FEW
HR PRD OF MIXED PCPN AT ONSET MAINLY N&W OF A SBY-XSA-PTB-FVX LINE.
JUST RAIN TO THE S OF THERE.
UPSHOT WILL BE RAIN MIXED WITH SLEET FOR A FEW HRS RIGHT ALONG THE
ABOVE MENTIONED LINE. PCPN SHUD START OUT AS A SNOW/SLEET MIX N&W
OF ASHLAND-CUMBERLAND LINE THEN CHANGE TO A RAIN/FZ RAIN MIX. INCRSD
POPS TO CATEGORICAL AFTR 06Z ACROSS SWRN CNTYS. TMPS INITIALLY DROP
DRNG THE EVE THEN LVL OFF OR SLOWLY RISE AFTR MIDNITE. LOWS GNRLY
L-M30S XCPT ARND 30 IVOF SBY TO ARND 40 SERN BEACH AREAS.
AFTR COORD WITH LWX/RNK...DECIDED TO HOLD OFF ON ANY WINTER W ADVSRYS
WITH THIS PACKAGE SINCE THIS IS STILL A LATE SCND/ERLY THIRD PRD EVENT
WITH LTL IF ANY ICE/SNOW ACCUMULATION XPCTD. CNTYS THAT STAND THE
BEST CHC FOR ANY ICE ACCUM WUD BE LOUISA/FLUVANNA & PSBLY CUMBERLAND.
PCPN CHANGES TO ALL RAIN ACROSS ENTIRE FA SUN MORN...ALTHOUGH THERE
CUD STILL BE POCKETS OF FZ RAIN ACROSS LOUISA/FLUVANNA CNTYS THRU 12Z.
LOW PRS PROGGED TO MOVES NE ACROSS THE NC/VA CSTL PLAIN RGNS SUN.
THIS TRACK POSES SOME INTERESTING TMP RANGES ACROSS FA. LOW LEVEL
WEDGE HOLDS TIGHT ACROSS NWRN CNTYS MOST OF THE DAY. THIS E-NE
FLOW RESULTS IN TMPS HOLDING ARND 40. WNDS TURN TO THE S SUN AFTRN
ACROSS CSTL SCTNS AS LOW PRS MOVES NE. THIS BRINGS IN SOME WRMR
AIR WITH TMPS RISING TO ARND 60 IVOF OUTER BANKS/VA BCH AREAS.
ALTHOUGH NOT IMPRESSIVE...ENUF INSTABILITY DVLPS ALONG THE SERN
CSTL AREAS SUN AFTRN. SO ADDED ISLTD THUNDER N OF ALBEMARLE SND ON
NE TO VA BCH.
LOW / UPR TROUGH PUSH OFF THE COAST SUNDAY NIGHT...WITH THE FLOW
TURNING WESTERLY. THIS ALLOWS THE RAIN TO END QUICKLY AND COULD
EVEN SEE SOME QUICK CLEARING. HIGH PRESSURE SLIDES OVER THE AREA
MONDAY. COULD SEE SOME FOG DVLP WITH THE WET GROUND SUN NITE AND
STILL MILD DEW POINTS AS THIS IS VERY LITTLE COLD AIR BEHIND THIS
SYSTEM. THE DRY WEATHER CONTINUES INTO MONDAY WITH MILDER CNDTNS.
HIGHS IN THE 50S.
TOTAL QPF FOR THIS SYSTM SHUD AVG ARND ONE HALF INCH. LCLLY HIGHER
AMTS PSBL IN ANY CONVECTION THAT DVLPS ALONG THE COAST. THIS RNFL
NOT XPCT TO EFFECT ONGOING RVR FLOODING.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
NEXT COLD FRONT WILL BE APPROACHING TUESDAY. MODELS DO NOT SHOW
ANY PHASING OF NORTHERN AND SOUTHERN STREAMS UNTIL OFFSHORE SO
JUST A STRONG COLD FRONT WITH LOW TO THE NE. THIS WILL AGAIN BRING
IN SOME RAIN AS ALL MODELS SHOWING IT LATE TUESDAY INTO EARLY
WEDNESDAY. BELIEVE WITH STRONG DOWNSLOPE FLOW DEVELOPING AS COLD
FRONT EXITS PRECIP WILL END TO QUICK TO HAVE ANY CHANGE OVER TO
SNOW BEFORE ENDING AND TO WARM INITIALLY. MODELS AGAIN AGREE ON HIGH
PRESSURE TO W MOVING INTO THE REGION WITH ANOTHER COLD AIR MASS
FOR THE LATTER PART OF THE WEEK WITH TEMPS AGAIN WELL BELOW
NORMAL.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WL CONTINUE THROUGH SAT AS HI PRES REMAINS
OVER THE AREA. SCTD HI CLDS WL MV FROM W TO E OVER NC THROUGH THE
NIGHT. ELSEWHERE...EXPECT MSTLY CLR SKIES. THE HI CLDS WL
GRADUALLY MAKE THEIR WAY N SAT MRNG AS OUR NEXT SYSTEM APPROACHES
FROM THE SW. W WNDS AROUND 5 TO 10 KT WL CONTINUE OVERNIGHT
BEFORE BECOMING E/SE BY MIDDAY SAT.
SFC HI WL MV OVER THE RGN THEN E AND OFF THE ATL CST BY LATE SAT.
CIGS WL LWR SAT EVNG TO AROUND 5K FT WITH THE AID OF ONSHORE FLOW.
MOISTURE WITH THE NEXT SYS WL MV INTO COLD AIR ALREADY IN PLACE
AND BRING CHC FOR A WINTRY MIX LATE SAT INTO EARLY SUN...THEN
TRANSITION BACK TO RAIN BY LATE SUN AM THRU AFTN. MVFR/IFR CONDS
LIKELY TO AFFECT TAF SITES INTO LATE SUN/EARLY MON.
&&
.MARINE...
SCA FLAGS CONTINUE OVER THE NRN COASTAL WATERS TILL 4 AM (WINDS
DIMINISH THEREAFTER). LOW WATER ADVSY FOR THE CSTL WATERS
CONTINUES N OF CAPE CHARLES LIGHT FOR THE CURRENT LOW TIDE
CYCLE...TIDE GAGES AT OCEAN CITY AND WACHAPREAGUE SHOWING WATER
LEVELS ON THE ORDER OF 1.5 TO 2 FT BELOW NORMAL DUE TO THE STRONG
OFFSHORE FLOW OVER THE PAST 24-36 HRS. ALSO TO NOTE...HAVE MENTION
OF TIDES RUNNING A FOOT BELOW NORMAL OVER THE BAY AND REMAINDER OF
COASTAL ZONES THROUGH 7AM TDY.
MODELS FAIRLY CONSISTENT WITH NEXT SYSTEM MOVING ACROSS THE
WATERS ON SUNDAY AND SUNDAY NIGHT. THIS SYSTEM IS NOT FAIRLY WEAK
AND WILL KEEP WINDS BELOW SCA FOR NOW. WINDS ALOFT INCREASE
TUESDAY AHEAD OF A COLD FRONT APPROACHING. THE TIMING LOOKS VERY
SIMILAR ON ALL MODELS. LOOKING AT THE SOUNDINGS DO NOT SEE MUCH
CHANCE OF LOW LEVEL WINDS MIXING TO THE SURFACE AS WARM ADVECTION
ALOFT OVER THE NOW COOL WATERS WILL LIMIT THIS MIXING. ONCE THE
FRONT PASSES TUESDAY NIGHT INTO WEDNESDAY THE WINDS WILL BEGIN TO
MIX DOWN AND SHOULD AGAIN SEE SCA CONDITIONS. WILL HAVE SOME GUSTS
CLOSE TO GALE WEDNESDAY INTO THURSDAY.
&&
.HYDROLOGY...
DUE TO RECENT HVY RAINFALL...FLOOD WARNINGS REMAIN IN EFFECT FOR
RIC WESTHAM/FRANKLIN AND SEBRELL (EVEN THOUGH SEBRELL IS BRIEFLY
JUST BELOW FLOOD STAGE ATTM). SEE FLSAKQ FOR DETAILS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...LOW WATER ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR
ANZ650-652-654.
SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR
ANZ650-652-654.
&&
$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...MPR
LONG TERM...JAB
AVIATION...CCW
MARINE...CCW
HYDROLOGY...AKQ
