FXUS62 KRAH 100256
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
949 PM EST MON DEC 9 2003
   
...INCREASING CLOUDS OVERNIGHT... RAIN ARRIVES TUESDAY...

EVENING 00Z/10 DECEMBER DATA ANALYSIS SHOWED WEAK (1026 MB) SURFACE
HIGH PRESSURE OVER MAINE... RIDGING DOWN THE IMMEDIATE EAST COAST TO 
OFF WILMINGTON. HOWEVER, THERE WAS STILL DRY AIR AT THE SURFACE
OVER CENTRAL NC (SFC DEW POINTS IN THE LOWER TO MID 30S). A STRONG
SURFACE LOW (998 MB) WAS CENTERED OVER SW MISSOURI... WITH THE STRONG 
MID AND UPPER LEVEL LOW MOVING NE OVER NE OKLAHOMA. RADAR AND LIGHTNING
DATA INDICATE WEAKENING LINE OF CONVECTION FROM MEMPHIS TO JACKSON...
TO NEW ORLEANS AS THE LINE MOVED INTO MORE STABLE CONDITIONS
(DEW POINTS IN THE 40S OVER TN/AL). UPPER JETTING WAS FAIRLY WEAK...
WITH ENTRANCE REGION OF THE UPPER JET AT 70 KNOTS. ADEQUATE UPPER
DIVERGENCE HOWEVER SUPPORTING CONVECTIVE LINE TO OUR WEST.

AS THE SYSTEM MOVES NE... THE WARM CONVEYOR BELT OF MOISTURE WILL 
ARRIVE AHEAD OF THE SFC COLD FRONT TUESDAY. SURFACE DEW POINTS WILL 
SURGE UPWARD WITH NW-N INFLUX OF GULF/CARIBBEAN MOISTURE... BUT ONLY 
FROM THE CURRENT READINGS NOW IN THE 30S... INTO THE UPPER 40S/50S.
SOME LOWER 60S ARE INDICATED SE. THEREFORE... WITH UPPER DYNAMICS
PASSING WELL TO OUR NW... AND WITH VERY LIMITED INSTABILITY... EXPECT 
LITTLE IN THE WAY OF THUNDER. QPF OF 1/2 INCH TO POSSIBLY 1 INCH
NW APPEARS IN LINE. 

THE RECENT MESOETA AND 18Z GFS RUNS HAVE SPED UP RAIN ARRIVAL... MID
MORNING AROUND GSO/ALB TO AROUND NOON FAY/RDU. IN ADDITION... MESOETA 
STILL HINTS AT WEAK INSITU DAMMING NW PIEDMONT AS RAIN ARRIVES TRAPPING 
LOW LEVEL DEW POINTS IN THE 40S. THIS UPDATE WILL DROP HIGHS NW BY 2 
CATEGORIES... TO AROUND 50 GSO... AND SPEED UP TIMING OF RAIN ARRIVAL. 
THIS SYSTEM EXITS THE REGION DURING TUESDAY EVENING... FOLLOWED BY 
COOLING AND DRYING WED-THU.

AS FOR THE POTENTIAL FOR AN EAST COAST WINTER STORM SOMETIME IN THE 
SUNDAY OR MONDAY TIME FRAME... THE JURY IS HUNG. 

ALL MODELS SHOW A PARENT SURFACE HIGH CENTERED OVER NEW ENGLAND... 
THE MRF'S FORECAST OF A 1042 SURFACE HIGH OVER NY STATE ON SUNDAY 
WAS OBVIOUSLY THE MOST FAVORABLE FOR A CLASSICAL DAMMING EVENT. 
HOWEVER... THE EXTENT OF COLD/DRY AIR AND THE STRENGTH OF THIS PARENT 
HIGH ARE QUITE VARIABLE BETWEEN THE MODELS AND EVEN WITHIN A MODEL FROM 
RUN TO RUN. THE POSITION... STRENGTH... AND ORIGIN OF THESE HIGHS ARE 
OBVIOUSLY MAJOR PLAYERS IN ANY WINTER STORM PROCESS FOR CENTRAL NC. 

AS FAR AS THE AVAILABLE MOISTURE SOURCE... MODELS WERE AT ODDS IN THE 
STRENGTH/PLACEMENT OF A SUBTROPICAL JET SYSTEM WITHIN WHAT IS BECOMING 
A MUCH MORE ACTIVE SPLIT UPPER FLOW PATTERN (FAVORABLE FOR NC WINTER 
STORMS). THE 12Z UKMET ACTUALLY SHOWED SOME CUT OFF AT H5 OVER THE GULF 
COAST STATES... WITH A MUCH SLOWER AND OBVIOUSLY WARMER SURFACE SYSTEM. 
THE 18Z GFS CAME IN SHOWING A DECENT H5 SOUTHERN STREAM TROUGH WITH 
COASTAL SURFACE DEVELOPMENT... BUT MORE OFFSHORE THAN ANY PREVIOUS GFS 
RUNS. MOST OF THE PRECIPITATION WAS CONFINED TO THE IMMEDIATE COAST OR 
OFFSHORE.  THE ECMWF'S DEPICTION OF A SURFACE LOW MOVING UP THE WEST 
SIDE OF THE MOUNTAINS INTO A COLD SURFACE HIGH.. WITH NO COASTAL 
DEVELOP REALLY LOOKS SUSPECT. 

AT THIS POINT... THE SCENARIO THAT MAKES MOST SENSE WOULD BE THE  
GFS/MRF GIVEN THIS TYPE OF SPLIT FLOW PATTERN... WITH A SOME TYPE OF 
COASTAL DEVELOPMENT. BUT WILL IT BE CLOSE ENOUGH TO HAVE A MAJOR IMPACT 
OVER INLAND CENTRAL NC? IF SO... THEN PATTERN RECOGNITION SUGGESTS A 
NARROW P-TYPE TRANSITION... WITH "MILLER TYPE A" COASTAL LOW. A 1040+ 
MB HIGH OVER NY STATE OF ARCTIC ORIGIN WITH CLASSICAL CAD INTO SC... 
WOULD CERTAINLY SWAY THE JURY AS TO THE P-TYPE DISTRIBUTION WITH
"MILLER A" STORM TRACK UP THE COAST. BUT FOR NOW... THE JURY REMAINS 
HUNG. NO CHANGES TO THE GRIDS/FORECAST FOR NOW. 

.RAH...NONE.

BADGETT