FXUS62 KGSP 151314
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
814 AM EST TUE DEC 15 2009

.SYNOPSIS...
STRONG HIGH PRESSURE WILL BUILD IN FROM THE MISSISSIPPI VALLEY 
TODAY...THEN GRADUALLY WEAKEN INTO THE SECOND HALF OF THE WEEK.  LOW 
PRESSURE WILL DEVELOP OVER THE GULF LATE IN THE WEEK AND CROSS 
FLORIDA OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
I/VE ISSUED A FOG ADVISORY FOR THE NEXT TWO HOURS FOR MOST OF THE 
NON-MTN PARTS OF THE FA. WHILE THE FLOW HAS STARTED TO TURN OUT OF 
THE NORTHWEST...THE DOWNSLOPE IS STILL WEAK. THIS COUPLED WITH A 
HIGH CLOUD COVER WILL MAKE IT HARD FOR THE FOG TO DISSIPATE. 

PREVIOUS DISCUSSION...
AFTER A FOGGY START EARLY THIS MRNG THE COLD FRONT WILL MOVE ACROSS 
THE MTNS...THEN THROUGH THE PIEDMONT THIS AFTN. KEPT MENTION OF 
LIKELY SHWRS SW CWA EARLY...TAPERING TO SLIGHT CHC N AND E...THEN 
MAINLY JUST A CHC ACROSS THE S ZONES FROM AROUND DAYBREAK INTO EARLY 
AFTN. A SLIGHT CHC WILL CONT THRU THE EVE OVER THE MTNS IN NW 
UPSLOPE FLOW WITH SNOW PSBLY MIXING IN BEFORE PRECIP ENDS. LINGERING 
LOW CLOUDS AND JET CIRRUS THIS AFTN WILL LIMIT INSOLATION SOMEWHAT 
BUT STRONGER COLD ADVECTION WILL BE WELL BEHIND THE FRONT AND WITH 
NW DOWNSLOPE FLOW...STILL EXPECT MAX TEMPS TO WARM INTO THE L60S N 
AND CNTRL PIEDMONT WITH A FEW M60S S AND MAINLY L-M50S MTNS. HIGH 
PRES BUILDS IN TONIGHT. WITH LOWERING THKNS VALUES EXPECT LOWS IN 
THE M-U30S AT THE LOWER ELEVS...M20S-L30S MTNS.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 135 AM TUESDAY...DRY/CONFLUENT UPPER FLOW OVER THE EASTERN 
CONUS WILL MAKE FOR A VERY QUIET SHORT TERM...AS CANADIAN HIGH 
PRESSURE RIDGE DOMINATES IN THE LOW LEVELS. THE ONLY ITEM OF MILD 
INTEREST IS THAT IT DOES APPEAR THAT A PERSISTENT ACTIVE SOUTHERN 
STREAM (ALBEIT SUPPRESSED WELL SOUTH OF THE GULF COAST)...AIDED AND 
ABETTED BY THE POSITION OF THE JET STREAM JUST TO OUR NORTH...MAY 
ENSURE THAT PLENTY OF CIRRUS REMAINS OVER THE AREA THROUGH THE 
PERIOD. THIS SHOULD ALLOW MAX TEMPS TO BE A BIT COOLER (NEAR 
CLIMO)...AND LOWS A BIT WARMER (ALSO NEAR CLIMO) THAN THEY OTHERWISE 
WOULD BE.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 145 AM TUESDAY...THE MEDIUM RANGE MODELS SEEM TO BE COMING 
INTO A BIT BETTER AGREEMENT.  SEEMS TO BE FAR GREATER CONFIDENCE 
THAT THERE WILL BE SHARP HEIGHT FALLS DURING THE UPCOMING WEEKEND 
WITH A DEEP UPPER TROUGH WHICH MAY LINGER INTO EARLY NEXT WEEK.  TO 
START THIS PERIOD...12Z FRIDAY...THE GFS...ECMWF AND GEM ALL HAVE A 
SURFACE LOW OVER THE EASTERN GULF WHICH MOVES IN SOME FASHION OVER 
FLORIDA.  THE GFS AND ECMWF HAVE THIS LOW MOVING EAST NORTHEAST AND 
JUST FAR ENOUGH AWAY TO KEEP PRECIP OUT OF OUR FORECAST AREA.  I 
RAISED THE POP TO 14 IN SOUTHEAST ZONES FRIDAY AND FRIDAY NIGHT JUST 
TO SAY PRECIP IS NOT FAR AWAY TO THE SOUTHEAST.  AS WE GET INTO THE 
WEEKEND...THE GFS IS MORE PROGRESSIVE WITH THE UPPER TROUGH MOVING 
OVER OUR AREA THEN OUT FOR THE START OF NEXT WEEK.  BOTH OF THESE 
MODELS HAVE SPOKES OF ENERGY ROTATING AROUND THE BRINGING IN 
NORTHWEST FLOW MOISTURE UP AGAINST THE NC MOUNTAINS WITH A PROLONGED 
PERIOD OF SNOW SHOWERS.  THE ECMWF WOULD KEEP WELL BELOW NORMAL 
TEMPERATURES ACROSS OUR AREA INTO THE MIDDLE OF NEXT WEEK.  THE GFS 
HAS THE HEIGHTS BEGINNING TO RISE FROM THE WEST ON MONDAY. DID NOT 
MAKE MANY CHANGES TO PREVIOUS FORECAST BUT DID LOWER TEMPERATURES A 
BIT MORE AS THE EFFECTS OF THE TROUGH ENTRENCHES ITS WAY OVER OUR 
AREA.  ADDED SLIGHT CHANCE POPS FOR SNOW SHOWERS ALONG THE NC/TN 
BORDER NORTH OF ASHEVILLE MONDAY AND MONDAY NIGHT.

&&

.AVIATION /13Z TUESDAY THROUGH SATURDAY/...
KCLT AND ELSEWHERE...FOG/STRATUS SHOULD BEGIN TO LIFT BY MID-LATE 
MRNG AS A COLD FRONT CROSSES THE AREA...BECMG VFR LATER THIS AFTN 
WITH NW DOWNSLOPE WINDS BEHIND FRONT. LOW CLOUDS WILL LINGER AT KAVL 
IN GUSTY NNW UPSLOPE FLOW. WINDS SHOULD STAY AT LEAST 8-10KT 
OVERNIGHT WITH DRYER AIR MOVG IN...SO NO RESTRICTIONS EXPECTED.
 
OUTLOOK...UNRESTRICTED CIG/VSBY WED-FRI IN DRYER AIRMASS BEHIND COLD 
FRONT. A WEAK SYSTEM APPROACHES FROM THE W SAT...POSSIBLY BRINGING 
LOWER CIG/VSBY AND SCT RAIN OR SNOW SHOWERS TO THE MTNS.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR GAZ018-026-
     028-029.
NC...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR NCZ035>037-
     056-057-068>072-082-502-504-506-508-510.
SC...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR SCZ004>014-
     019.

&&

$$
SYNOPSIS...DEO
NEAR TERM...MCAVOY/RB
SHORT TERM...JDL
LONG TERM...DEO
AVIATION...RB