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000
FXUS61 KAKQ 090351
AFDAKQ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
1051 PM EST SUN DEC 8 2013

.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL MOVE NORTHEAST JUST WEST OF THE
APPALACHIANS THROUGH MONDAY MORNING...WHILE A SECOND LOW PRESSURE
AREA TRACKS NORTHEAST JUST OFF THE MID ATLANTIC COAST.
MEANWHILE...HIGH PRESSURE WILL SLOWLY RETREAT NORTHEAST OVER NEW
ENGLAND. ANOTHER LOW PRESSURE SYSTEM WILL MOVE ACROSS THE CAROLINAS
MONDAY NIGHT INTO TUESDAY. HIGH PRESSURE BUILDS IN FROM THE
NORTHWEST TUESDAY NIGHT AND WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
MID-EVENING WATER VAPOR IMAGERY/VWP SHOWING STRONG SWLY FLOW (WAA)
ALOFT FROM SOUTHERN MEXICO UP INTO THE MID-ATLANTIC REGION.
MEANWHILE, AT THE SFC, STRONG CAD WEDGE HOLDING STRONG, WITH N-NE
FLOW IN PLACE BELOW 1KFT. REGIONAL RADAR MOSAIC INDICATING NEXT
SLUG OF OVERRUNNING MOISTURE CURRENTLY MAKING ITS WAY FROM THE
WESTERN CAROLINAS INTO THE FAR NW CORNER OF THE CWA. FORCING WILL
CONTINUE TO CONFINE MAJORITY OF THIS PCPN ACROSS NW THIRD OF THE
AREA THROUGH 06-08Z. TEMPS HAVE BEEN A BIT MORE STUBBORN TO DROP
OFF THAN PREVIOUSLY THOUGHT, WITH MESONET OBS SHOWING WESTERN
SECTIONS OF AMELIA, CFIELD/HENRICO STILL AT/JUST BELOW 32 AT 03Z.
THIS IS CONSISTENT WITH LATEST NAM/SREF SOLNS...AND FAIRLY TYPICAL
OF CAD SETUPS SUCH AS THESE.

CONSIDERATION WAS GIVEN TO EXTEND ADVISORY FOR FZDZ/FZRA INTO
THESE AREAS. HOWEVER, MOST AREAS IN THOSE COUNTIES ARE ALREADY AOA
32 F...AND MODEST INCREASE IN TEMP SHOULD SIGNIFICANTLY LIMIT ANY
ADDITIONAL OPERATIONAL IMPACT FROM ICE ACCRUAL. THUS, DECISION WAS
MADE TO HOLD OFF WITH ANY ADDITIONAL HEADLINES OVERNIGHT. CAVEAT
TO THAT IS THAT...GIVEN BEST FGEN FORCING ALONG/JUST NORTH OF THE
AREA...ADVY HAS BEEN RETAINED NORTH OF RIC METRO IN EXPECTATION OF
SOME SLICK SPOTS. ONCE AGAIN EXPECT NW PORTIONS OF THE ADVY AREA
TO BE MOST PRONE TO SLICK SPOTS. OTHERWISE, WINTER STORM WARNING
REMAINS IN GOOD SHAPE.

AS STATED ABOVE...TEMPERATURES WILL BE STEADY OR SLOWLY RISING AS
THE HIGH PRESSURE TO THE NORTH MOVES OFF THE COAST AND THE COLD
AIR DAMMING GRADUALLY ERODES TOWARDS MORNING.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
THE PRIMARY SHORTWAVE FORCING PULLS OFF TO THE NORTHEAST MONDAY
MORNING...WITH A MOIST MID-LEVEL AIRSTREAM LINGERING OVER CENTRAL
AND SE PORTIONS OF THE LOCAL AREA. FORECAST SOUNDINGS REMAIN RATHER
SATURATED AT THE LOW-LEVELS...SO AREAS OF LIGHT RAIN AND/OR DRIZZLE
SHOULD PERSIST...BUT OVERALL QPF SHOULD BE LIGHT. TEMPERATURES WILL
GRADUALLY WARM A FEW DEGREES...BUT WILL REMAIN IN VICINITY OF 32F
FOR THE NW PIEDMONT COUNTIES...SO A FEW POCKETS OF FZRA COULD LINGER
EARLY. SIDED WITH THE COOLER MET GUIDANCE FOR HIGHS GIVEN THE CLOUD
COVER AND A GRADUALLY ERODING CAD WEDGE SCENARIO...WHICH SUPPORTS
HIGHS RANGING FROM AROUND 40 NW...TO THE MID/UPPER 40S FOR THE
INTERIOR COASTAL PLAIN AND BAY-SIDE OF THE EASTERN SHORE. FAR SE
PORTIONS WILL BE MILDER WITH HIGHS IN THE MID 50S TO NEAR 60.

THE FINAL SHORTWAVE RACES NORTHEAST FROM THE SOUTHEAST STATES AND
AFFECTS THE LOCAL AREA LATE MONDAY NIGHT INTO TUESDAY AFTERNOON.
LOW-LEVEL THICKNESS VALUES FALL ACROSS THE NORTHERN ZONES DURING THE
DAY. BUFR SOUNDINGS SUGGEST A TRANSITION TO SN ACROSS THE N...BUT
THIS WILL ULTIMATELY BE DICTATED BY SURFACE TEMPERATURES...WHICH AT
THIS TIME ARE FORECAST TO LINGER AROUND 35F. GIVEN THIS...WILL
FORECAST A MIX OF RA/SN MAINLY FROM THE NW PIEDMONT TO THE EASTERN
SHORE.

HIGH PRESSURE FINALLY BUILDS IN FROM THE NW TUESDAY NIGHT INTO
WEDNESDAY BRINGING DRIER CONDITIONS. LOWS TUESDAY NIGHT SHOULD RANGE
FROM THE LOW 20S NW...TO THE LOW 30S SE...FOLLOWED BY HIGHS
WEDNESDAY OF 40-45.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
COLD AND GENERALLY DRY IN THE EXTENDED FROM THURSDAY INTO NEXT
WEEKEND. BOTH GFS AND ECMWF ALL CONTINUE WITH COLD HIGH PRESSURE
OVER THE AREA THURSDAY AND FRIDAY. BY THE WEEKEND THE MODELS BEGIN
TO DIVERGE AND HAVE A FAIRLY LARGE SPREAD. THE FEATURE INFLUENCING
NEXT WEEKENDS WEATHER IS STILL OVER THE PACIFIC. BOTH MODELS AGREE
ON SOME POTENTIAL FOR PRECIPITATION BY SATURDAY AND SUNDAY. LOTS OF
UNCERTAINTY WITH THE LOW AND HOW COLD IT WILL BE. THERE IS EVEN
UNCERTAINTY IF ANY OF THE PRECIPITATION WILL MAKE IT THIS FAR NORTH.
THE GFS IS THE WARMER MODEL. EARLIER THE ECMWF ALSO WAS WARMER BUT
THE 12Z RUN IS MUCH COLDER. THIS LEADS TO UNCERTAINTY OF
PRECIPITATION TYPE FOR NEXT WEEKEND. FOR NOW WILL CONTINUE WITH A
RAIN SHOWER FORECAST WITH TEMPERATURES ABOVE FREEZING.

&&

.AVIATION /04Z MONDAY THROUGH FRIDAY/...
AS OF 00Z...STRONG LOW LEVEL WARM ADVECTION (I.E. AT 925 MB OR
2500 FT) WILL CONTINUE THROUGH THE EVENING HOURS WHILE WEAK COLD
ADVECTION CONTINUES NEAR THE SURFACE. A VERY MOIST BOUNDARY LAYER
WITH A STEEP LOW LEVEL INVERSION SHOULD MAINTAIN IFR CIGS AT ALL
THE TAF SITES THROUGH THE TAF PERIOD. PERIODS OF LIGHT RAIN OR
DRIZZLE WILL BE PSBL AS WEAK UPPER LEVEL DISTURBANCES PASS OVER
THE AREA.

OUTLOOK...IFR CIGS ARE LIKELY TO PERSIST INTO MONDAY NIGHT WITH
SOME IMPROVEMENT TUESDAY. PERIODS OF RAIN ARE PSBL INTO TUESDAY.
CLEARING IS EXPECTED TUESDAY NIGHT WITH VFR/DRY WX WEDNESDAY THROUGH
FRIDAY.

&&

.MARINE...
7 PM UPDATE...EXTENDED SCA FOR COASTAL WATERS S OF PARRAMORE
ISLAND FOR SEAS OF 5 FT OR HIGHER THROUGH 4 AM.

10 PM UPDATE: EXTENDED SCA FOR MOUTH OF THE BAY. EXTENDED SCA
NORTH OF PARRAMORE ISLAND TIL 10 AM FOR SEAS WHICH ARE BEING
ENHANCED BY STRONG EAST WINDS THROUGH EARLY MONDAY MORNING.

PREVIOUS DISCUSSION...
LATE SUN AFTN...SFC HI PRES WAS CNTRD OVR NEW ENGLAND WITH ONE LO
PRES AREA LOCATED OVR ERN KY AND A SECOND LO PRES AREA CNTRD JUST
OFF THE NC/SC CST. THIS SCENARIO WAS MAINTAINING RATHER STRONG NNE
WINDS OVR MUCH OF THE WTRS. SCA`S WILL REMAIN IN EFFECT FOR THE
NRN TWO CHES BAY ZNS AND THE CURRITUCK SND UNTIL 7 PM...WITH THE
REST OF THE CHES BAY AND CSTL WTRS UNTIL AT LEAST 10 PM. WINDS
WILL DIMINISH LATER THIS EVENG...THEN SHIFT TO THE W OR NW BY MON
MORNG...AS WEAK LO PRES LIFTS NNE TO JUST OFF THE DE CST. WINDS
WILL THEN BE SW 15 KT OR LESS ON MON. A COLD FRNT PUSHES THRU THE
REGION MON NGT INTO TUE MORNG...FOLLOWED BY HI PRES BLDNG IN FOR
TUE NGT AND WED.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR VAZ048-049-
     060>062-069.
     WINTER WEATHER ADVISORY UNTIL 4 AM EST MONDAY FOR VAZ063-064-
     072>076.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST MONDAY FOR ANZ634-654-656-
     658.
     SMALL CRAFT ADVISORY UNTIL 10 AM EST MONDAY FOR ANZ650-652.

&&

$$
SYNOPSIS...AJZ/MAM
NEAR TERM...AJZ/MAM
SHORT TERM...AJZ
LONG TERM...JAB
AVIATION...LSA
MARINE...TMG/LSA