FXUS61 KAKQ 102332
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
632 PM EST THU DEC 10 2009

.SYNOPSIS...
COLD HIGH PRESSURE BUILDS INTO THE AREA THIS AFTERNOON THROUGH
SATURDAY...THEN MOVES OFF THE MID ATLANTIC COAST SATURDAY NIGHT.
A COUPLE WEAK LOW PRESSURE SYSTEMS...ONE OFF THE CAROLINA COAST
AND ONE MOVING THROUGH THE GREAT LAKES...AFFECTS THE AREA LATE
SATURDAY NIGHT AND SUNDAY. HIGH PRESSURE WITH MODERATING
TEMPERATURES ARRIVE FOR EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
THE BROAD POLAR LOW CONTINUES TO SPIN NEAR HUDSON AND THE COLD
ADVECTION CONTINUES AS THE FLOW TURNS MORE NORTHWEST TONIGHT. THIS
WILL CONTINUE TO PUSH COLDER AND DRIER AIR INTO THE REGION. EXPECT
THAT WINDS WILL CONTINUE TO BE GUSTY EARLY TONIGHT AS THE GRADIENT
REMAINS IN PLACE. BUT AS HIGH PRESSURE BUILDS IN LATER THE
GRADIENT SHOULD BEGIN TO RELAX A LITTLE...BUT SHOULD NOT BE
ENOUGH TO ALLOW DECOUPLING. SO FOR LOW TONIGHT HAVE LEANED JUST A
TOUCH ABOVE GUIDANCE.  

HIGH PRESSURE THEN CONTINUES ITS EASTWARD MOVEMENT ON
FRIDAY...SETTLING OVER THE ARE BY FRIDAY NIGHT. THIS WILL KEEP THE
CLEAR SKY IN PLACE WITH LOTS OF SUNSHINE...BUT WARMING WILL BE
TOUGH AS 850 MB TEMP ARE AROUND -8C TO -10C. HAVE GONE WITH THE
COOLER MET WITH HIGHS IN THE UPPER 30S TO LOWER 40S. BUT COULD SEE
TEMPS STRUGGLING TO CLIMB THOSE VALUES. RADIATIVE CONDITIONS ARE
BETTER ON FRIDAY NIGHT...SO DESPITE SOME LIGHT WARM ADVECTION
BEGINNING..EXPECT FRIDAY NIGHT TO BE JUST AS COLD WITH READINGS IN
THE TEENS AND LOWER 20S.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
THE AREA OF HIGH PRESSURE HANGS AROUND ON SATURDAY BUT THEN BEGINS
TO RETREAT NE ON SATURDAY NIGHT...LEAVING A WEDGE AREA OF DRY COOL
AIR IN PLACE. THE MODELS HAVE NOW ALL JUMPED TOWARD HAVING SYSTEMS
APPROACH LATE SATURDAY NIGHT AND MOVE THROUGH ON SUNDAY. AT THIS
POINT...IT LOOKS MAINLY LIKE A WARM ADVECTION/ISENTROPIC LIFT
SCENARIO AS ONE WEAK SHORTWAVE LIFTS ACROSS THE OHIO VALLEY AND A
WEAK SURFACE LOW FORMS ALONG THE CAROLINA COAST AND LIFTS NE
DURING THE DAY SUNDAY. AS THE MOISTURE OVER RUNS THE COLD DRY
AIRMASS IN PLACE...COULD EASILY SEE SOME WINTRY PCPN ON THE
LEADING EDGE...BUT IT SHOULD CHANGE TO RAIN PRETTY
QUICKLY...EXCEPT FOR FAR WESTERN PORTIONS OF CWA WHERE THE WEDGE
WILL HOLD LONGER. QPF AMOUNTS ARE NOT EXPECTED TO BE VERY
HIGH...BUT UP TO A HALF INCH IS POSSIBLE. 

FOR TEMPERATURES...SHOULD BEGIN TO SEE THINGS MODERATE ON SATURDAY
AS 850 TEMPS CLIMB IN SW FLOW. BUT TIMING OF THE CLOUDS AND PCPN
SATURDAY NIGHT WILL HAVE A BIG IMPACT ON OVERNIGHT LOWS SATURDAY.
THE FASTER THEY ARRIVE THE LESS TEMPERATURES WILL FALL. FOR NOW
HAVE PLAYED A NON DIURNAL TRACE WITH READINGS DROPPING EARLY AND
THEN RISING AFTER MIDNIGHT. THIS TEMP TREND WILL IMPACT PCPN TYPE
GREATLY. WILL NEED TO CONTINUE TO MONITOR THIS AS A COLDER
SCENARIO COULD LEAD TO WINTRY WEATHER ISSUES.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HV ALLOWED FOR A FEW REMNANT SHRAS SUNDAY NIGHT AS SFC LOW EXITS TO 
THE NE AND SFC WEDGING STARTS TO BREAK DOWN. BY 
MONDAY/TUESDAY...WNDS LOOK TO BACK FROM THE WNW TO THE SSW AHEAD OF 
AN APPROACHING COLD FRONT FROM THE MS VLY/MIDWEST. NEW ECMWF HAS 
COME INTO BETTER AGREEMENT WRT TIMING FRONTAL PASSAGE TUESDAY 
MORNING...SO HV GONE WITH CHC POP ALL ZONES TUESDAY COINCIDENT WITH 
FROPA...BUT WL STAY IN LOW CHC RANGE FOR NOW. TRANSITION TOWARDS A 
MORE PRONOUNCED EAST COAST TROUGH INTO THE LATE WEEK PERIOD SHOULD 
ALLOW FOR A COOLER END TO THE WEEK...WITH TEMPERATURES POTENTIALLY 
FALLING TO ~ 0.5 TO 1 S.D. BELOW NORMAL VALUES LATE NEXT WEEK...INTO 
THE U30S TO ARND 40 NW...INTO THE L/M 40S ACROSS SERN COUNTIES.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/... 
NO MAJOR CHANGES IN STORE AS FCST LOOKS TO BE ON TRACK. HI PRES
OVER THE MID MS VLY WL MV EWD INTO THE MID ATLANTIC STATES KEEPING
VFR CONDS THROUGH FRI. EXPECT WSTRLY WNDS AROUND 10 KT KT TO
CONTINUE OVERNIGHT AT INLAND SITES. COULD SEE SOME GUSTS UP TO 20
KT AT CSTL SITES AS MIXING WL HELP TO BRING SOME WNDS ALOFT TO THE
SFC.

HI PRES BLDS INTO THE MID ATLANTIC STATES THROUGH EARLY SAT. THE
NEXT IN A SERIES OF WEATHER SYSTEMS WL BRING A GOOD CHC OF PCPN
AND LOWER VSBYS/CIGS TO THE TAF SITES (MVFR TO POSSIBLY IFR)
BEGINNING ON SUN.

&&

.MARINE...
SCA CONDITIONS CONTINUE ACROSS THE WATERS THIS AFTN...AS ANOTHER 
SURGE IS ANTICIPATED TONIGHT AS AN UPR LVL TROUGH PUSHES THROUGH THE 
REGION LATE EVE INTO THE OVRNT. HV DECIDED TO FOREGO THE GALE 
WARNING FOR THE NORTHERN COASTAL ZONES NOW...AS NAM/GFS BOTH DEPICT 
H92-85 WNDS ON THE ORDER OF 30-40 KT LT TONIGHT TWRDS DAYBREAK FRI 
OVER THE NORTHERN WATERS. EXPECT THAT WE MAY SEE A ROGUE OB OR TWO 
TO GALE...BUT WOULD RATHER NOT CARRY GALE WARNING IN THAT SCENARIO 
WITH STRONG SCA WNDS MORE THAN LKLY TO BE THE PREDOMINANT CONDITION 
THROUGHOUT TONIGHT.

WESTERLY FLOW CONTS FRI...AS SFC HIGH PRES BUILDS SETTLES OVER THE 
WTRS FOR LT TOMORROW INTO SAT. SCA FLAGS SHOULD CONTINUE OVER 
COASTAL WATERS FOR MUCH OF THE DAY ON FRI BEFORE GRADIENT RELAXES 
AND SEAS SLOWLY SUBSIDE. ANOTHER PD OF INCRSD LLVL ONSHR WNDS ON SUN 
AS WEAK SFC LOW PRES TRACKS BY JUST S OF THE WTRS.

TIDES...GUIDANCE STILL PROGGING ANOMALIES ~ 1.0 FT ABOVE NRML FOR 
MUCH OF THE BAY AND VA/MD CSTL ZONES. WL OUTLOOK TIDES RUNNING 1 TO 
1.5 FT ABV NORMAL WITH CWF FOR NEXT TIDE CYCLE...BUT SHOULD SEE 
ANOMALIES DIMINISH AS WESTERLY FLOW CONTINUES TONIGHT.

&&

.HYDROLOGY...
RUNOFF FROM TUESDAY AND WEDNESDAY'S RAINFALL IS NOW BEGINNING TO 
WORK ITS WAY THROUGH THE HYDROLOGIC SYSTEM INTO THE LOWER PORTIONS 
OF THE JAMES...APPOMATTOX AND CHOWAN AND LOWER ROANOKE BASINS. MOST 
OF THE RIVERS HAVE CRESTED OR ARE CLOSE TO CREST AND SHOULD BEGIN 
FALLING INTO THE MORNING HOURS OVER THE NEXT FEW DAYS. IN 
VIRGINIA...NO FLOOD WARNINGS REMAIN ON THE APPOMATTOX RIVER. 
HOWEVER...FLOOD WARNINGS CONTINUE FOR THE LOWER JAMES RIVER IN THE 
RICHMOND METRO AREA....THE MEHERRIN NEAR LAWRENCEVILLE...THE LOWER 
NOTTOWAY RIVERS AND BLACKWATER RIVER IN THE FRANKLIN VICINITY. IN 
NORTHEAST NORTH CAROLINA....THE FLOOD WARNING CONTINUES FOR THE 
CASHIE RIVER NEAR WINDSOR. OVERALL ALL AREA RIVERS WILL REMAIN AT 
LEVELS ABOVE NORMAL OVER THE NEXT SEVERAL DAYS. FORECAST RAINFALL 
OVER THE NEXT WEEK OR SO WILL HAVE SOME EFFECT ON THE RATE IN WHICH 
THESE RIVERS FINALLY RECEDE TO NORMAL LEVELS.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EST FRIDAY FOR ANZ630>633-650-
     652-654-656-658.

&&

$$
SYNOPSIS...ESS
NEAR TERM...ESS
SHORT TERM...ESS
LONG TERM...MAM
AVIATION...AM
MARINE...MAM
HYDROLOGY...KLL