990
FXUS61 KAKQ 240053
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
853 PM EDT WED JUL 23 2008
SYNOPSIS
A COLD FRONT WILL SLOWLY MOVE ACROSS THE REGION THROUGH THURSDAY
MORNING...THEN STALL OFF THE COAST THURSDAY AFTERNOON. WEAK HIGH
PRESSURE WILL BUILD IN FOR FRIDAY...WITH ANOTHER AREA OF LOW
PRESSURE MOVING THROUGH THE REGION THIS WEEKEND.
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
AFTR COORD WITH SPC/NEIGHBORING WFO'S...DECIDED TO LET SVR TSTRM BOX
EXPIRE AT 8PM. AIRMASS FAIRLY WORKED OVR FROM ACTIVITY DRNG PAST SVRL
HRS...BUT STILL CAN NOT RULE OUT A FEW PULSE TYPE CELLS (OVR THE
PIEDMONT) OVR THE NEXT HR OR SO GIVEN ANY CELL FROM THE LINE APPRCHG
FROM THE W THAT MERGES WITH THE ONGOING CELLS ACROSS THE PIEDMONT.
DROPPED SVR THREAT WORDING IN ZFP...BUT KEPT HVY RAIN GIVEN
PROGGED PW'S AND THAT THE FA IN A FLOOD WTCH THRU THE NITE. CONT
CAT POPS AS UPR TROF ENHANCES ECHO COVERAGE AS NITE PROGRESSES.
SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/
WITH A TROF OF LOW PRESSURE ANCHORED TO THE NORTH OF THE GREAT
LAKES THROUGH THE PERIOD WILL HAVE NORTHWEST UPPER FLOW ACROSS THE
AREA. NEXT SHORTWAVE CIRCLING AROUND THIS TROF WILL AFFECT THE
AREA ON SATURDAY. SO EXPECTING DRY WEATHER BY THURSDAY NIGHT AND
FRIDAY. IT WILL STILL BE AT OR ABOVE NORMAL WITH HIGHS IN THE
UPPER 80S AND LOW 90S AND LOWS IN THE 60S. WILL TRIM BACK MOS
GUIDANCE MAXES SOME EACH DAY.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
AN UNSETTLED WEATHER PATTERN WILL CONTINUE FOR THE FORESEEABLE
FUTURE AS A STUBBORN UPPER LEVEL TROUGH REMAINS PARKED OVER THE ERN
US THRU AT LEAST EARLY NEXT WEEK. SEVERAL SHORTWAVE TROUGHS AND WEAK
SFC FRONTS WILL ROTATE THRU THE AREA AND HAVE CHANCE POPS (30-40%)
EACH AFTERNOON/EVENING DURING PEAK HEATING HOURS...WITH 20-30% POPS
DURING EACH NIGHT/MORNING.
AS FOR TEMPS...HIGHS WILL BE IN THE UPR 80S/LWR 90S...WITH LOWS IN
THE UPR 60S/LWR 70S.
AVIATION /01Z THURSDAY THROUGH MONDAY/
COLD FRONT STRETCHED ACROSS REGION WITH ATTENDANT STRONG TO SEVERE
THUNDERSTORMS FROM KDCA TO KCLT. XPCT THESE STORMS TO CROSS THE
AREA WITH OCCASIONAL HEAVY RAIN...IFR VSBYS AND MVFR CIGS. MORE
TSRAS AHEAD OF FRONT AT 01Z ACROSS TIDEWATER AREA TO CONTINUE
THROUGH 03Z. FRONT WILL SLOWLY PUSH INTO CENTRAL VA OVERNIGHT BEFORE
STALLING ALONG COAST THURS AM. XPCT SHRAS AND SOME EMBEDDED TSRA
ACROSS THE AREA THRU 12Z WITH COAST SITES EXPERIENCING
PRECIP/REDUCED AVN CONDS UNTIL 18Z.
OTW...SKIES CLEAR BEHIND CD FROPA WITH HIGH PRESSURE BUILDING
THROUGH FRIDAY. NEXT CHC OF PRECIP/REDUCED AVN CONDS OVER THE
WEEKEND WITH WEAK FROPA.
MARINE
SOUTHERLY GRADIENT FLOW HAS DEFINITELY INCREASED TODAY AHEAD OF THE
SLOW MOVING FRONTAL BOUNDARY. LATEST OBS SHOWING WINDS AOA SCA
CRITERIA OVER THE BAY/SND AND COASTAL WATERS. SCA WINDS WILL
CONTINUE THROUGH AT LEAST A FEW HOURS AFTER MIDNIGHT TONIGHT.
AFTERWARDS WINDS SHOULD DIMINISH BY EARLY THURSDAY WITH A WEAKENING
GRADIENT AS THE FRONT INCHES TOWARDS THE COAST.
WAVE WATCH III HAS BEEN OVERDOING SEAS/WAVE HEIGHTS AND BASED ON THE
LATEST BUOY OBS (2 TO 3 FT IN THE SRN WATERS AND 3 TO 4 FT IN THE
NRN WATERS) HAVE ACCORDINGLY LOWERED FCST WAVE HEIGHTS. WAVES/SEAS
ARE STILL EXPECTED TO BUILD THOUGH THROUGH THE EVENING
HOURS...PEAKING AT 5 TO 6 FT OVER THE NRN MOST COASTAL ZONES AND 4
TO 5 FT OVER THE SRN ZONES. WAVES WILL BE 3 TO 4 FT IN THE BAY.
WAVES/SEAS WILL GRADUALLY SUBSIDE EARLY THURSDAY AS WINDS SLACKEN
OFF. WAVE PERIODS WILL RANGE FROM 5 TO 6 SECONDS AS WAVES/SEAS WILL
BE PRIMARILY WIND DRIVEN AND LOCALLY GENERATED.
SCA MAY NEED TO BE EXTENDED FOR A FEW HRS LONGER ON THURSDAY BUT
LEFT AS IS FOR NOW BASED ON PROJECTED TIMING OF DIMINISHING WIND
FIELD. SUB-SCA CONDITIONS WILL THEN CONTINUE THROUGH FRI AS WEAK
HIGH PRESSURE BUILDS IN FROM THE WEST. MARGINAL SCA'S ARE POSSIBLE
DURING THE WEEKEND AHEAD OF THE NEXT FRONT.
AKQ WATCHES/WARNINGS/ADVISORIES
MD...FLASH FLOOD WATCH UNTIL 8 AM EDT THURSDAY FOR MDZ021>025.
NC...NONE.
VA...FLASH FLOOD WATCH UNTIL 8 AM EDT THURSDAY FOR VAZ063-064-
070>078-080>100.
FLASH FLOOD WATCH UNTIL 2 AM EDT THURSDAY FOR VAZ048-049-
060>062-065>069-079.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EDT THURSDAY FOR ANZ650-652-
654.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT THURSDAY FOR ANZ630>633-
656-658.
SYNOPSIS...JAB
NEAR TERM...MPR
SHORT TERM...JAB
LONG TERM...JRL
AVIATION...BAJ
MARINE...JRL
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