FXUS62 KGSP 102002
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
302 PM EST THU DEC 10 2009

.SYNOPSIS...
STRONG HIGH PRESSURE WILL REMAIN IN PLACE OVER THE REGION THROUGH 
SATURDAY AFTERNOON. AN AREA OF LOW PRESSURE WILL DEVELOP TO OUR 
SOUTHWEST AND APPROACH THE CAROLINAS LATE SATURDAY INTO EARLY SUNDAY 
FOLLOWED BY ANOTHER LOW AND ITS ASSOCIATED COLD FRONT APPROACHING 
THE REGION FROM THE WEST NEXT TUESDAY.

&&

.NEAR TERM /THROUGH FRIDAY/...
THE UPPER TROUGH OVER THE CONTINENTAL US WILL PROGRESS AND DEAPMLIFY 
TONIGHT AND FRIDAY...WITH ZONAL FLOW OVER THE SOUTHEAST. A SURFACE 
HIGH WILL MOVE FROM THE MID MS RIVER VALLEY TO THE CENTRAL 
APPALACHIANS. THE PRESSURE GRADIENT ON THE EAST SIDE OF THIS HIGH 
WILL RELAX OVER THE SOUTHERN APPALACHIANS TONIGHT...WITH GUSTY WINDS 
REMAINING ONLY IN THE MOUNTAINS. THE WIND ADVISORY FOR THE NORTHERN 
NC MOUNTAINS WILL BE EXTENDED TIL MIDNIGHT...AS WILL THE LAKE WIND 
ADVISORY FOR THE CENTRAL NC MOUNTAINS. WITH LIGHT WINDS TONIGHT EAST 
OF THE MOUNTAINS AND ONLY SCATTERED CIRRUS...RADIATIONAL COOLING 
WILL TAKE MINIMUM TEMPERATURES SEVERAL CATEGORIES BELOW NORMAL AS 
THE COLD AIR MASS CROSSES THE MOUNTAINS. THE MOUNTAINS WILL ONLY BE 
A FEW DEGREES COOLER AS WINDS KEEP THE BOUNDARY LAYER MIXED.

CIRRUS INCREASES ON FRIDAY OVER THE SOUTHERN PERIPHERY OF THE 
SURFACE RIDGE...WELL NORTH OF A SURFACE FRONT IN THE GULF OF MEXICO. 
WINDS WILL BE LIGHT FROM THE NORTHWEST. MAXIMUMS TEMPERATURES WILL 
WARM TO NEAR NORMAL ALONG AND SOUTH OF INTERSTATE 85...BUT WILL BE 
SEVERAL CATEGORIES BELOW NORMAL ALONG INTERSTATE 40.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 300 PM THURSDAY...HIGH PRESSURE WILL REMAIN OVER THE REGION 
FRI NITE. WILL NOT BE THE BEST RADIATIONAL CONDITIONS WITH 
INCREASING HIGH CLOUD COVER. HOWEVER...LOWS WILL BE 10 TO 15 DEGREES 
BELOW NORMAL WITH THE VERY COLD AND DRY AIR MASS.

AS THE PREVIOUS SHIFT NOTED...WE ARE DEALING WITH LOW AMPLITUDE SRN 
STREAM SHORT WAVES WITH THIS NEXT PCPN EVENT...A TYPICAL BANE OF AN 
EL NINO WINTER. WHEN THE FORCING IS THIS WEAK...IT/S HARD TO KNOW 
JUST WHEN THE LLVL WARM ADVECTION WILL BECOME STRONG ENOUGH TO 
SUPPORT PCPN. ALSO...WITH SUCH A DRY RIDGE OF ARCTIC ORIGINS OVER 
THE REGION...THE WESTERN CAROLINAS WILL BE ONE OF THE LAST PLACES TO 
SEE PCPN OWING TO THE DEEP MASS OF COOL...DRY AIR. THEREFORE...I 
HAVE PUSHED PRECIP TIMING BACK EVEN FURTHER THAN PREVIOUS SHIFT. DO 
NOT EXPECT ANY SIGNIFICANT PRECIP UNTIL LATE AFTERNOON...AND THEN 
MAINLY ALONG I-26 AND WEST. BY THE TIME ANY SIGNIFICANT PRECIP 
DEVELOPS...THE MAJORITY WILL BE RAIN...BUT THERE COULD BE THE USUAL 
MIX IF SLEET AT THE BEGINNING. WITH THE VERY LATE PRECIP 
ONSET...HIGHS WILL BE WARMER THAN EXPECTED...BUT STILL AROUND 10 
DEGREES BELOW NORMAL.

THINGS CHANGE SAT NITE AS SIGNIFICANT ISENTROPIC LIFT AND WAA MOVE 
IN ACROSS THE SOUTHEAST. LOOKS LIKE PRECIP WILL SPREAD ACROSS THE 
AREA OVERNIGHT. HOWEVER...THERE IS DISAGREEMENT ON THE STRENGTH AND 
DEPTH OF THE COLD AIR. USING A BLEND OF PARTIAL THICKNESSES... 
SUGGESTS FREEZING RAIN WOULD BE THE MAIN P-TYPE THREAT. THERE COULD 
BE SOME SLEET BEFORE THE BETTER WAA KICKS IN. THE MAIN THREAT AREA 
WOULD BE THE NRN MTNS...BLUE RIDGE TO HENDERSON AND POLK COUNTIES... 
AND THE LOWER ELEVATIONS OF THE NC FOOTHILLS. AS OF NOW...IT LOOKS 
LIKE ACCRETIONS WOULD MAX OUT AT A TENTH OF AN INCH. THERE COULD BE 
A BRIEF MIX ELSEWHERE...BUT NO SIGNIFICANT ACCRETIONS EXPECTED. 
LOWS NEAR NORMAL.

PRECIP TAPERS OFF SUNDAY AS LIFT MOVES OUT OF THE AREA. TEMPS WARM 
AS WELL ENDING P-TYPE THREAT. HIGHS REMAIN AROUND 10 DEGREES BELOW 
NORMAL.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 235 PM THU...DRYING WILL LIKELY SET IN FROM THE W ON SUN 
NIGHT...WITH A BRIEFLY BUILDING UPPER RIDGE OVER THE SE PERSISTING 
THROUGH MON. THE PRECIPITATION LULL SHOULD BE A FAIRLY SHORT 
ONE...AS A NRN STREAM WAVE DIGS INTO THE UPPER MIDWEST AND A SRN 
STREAM WAVE DIGS INTO TX. THE GFS HAS A LITTLE MOIST UPGLIDE 
DEVELOPING AHEAD OF THESE FEATURES MON AFTERNOON...BUT THIS APPEARS 
A LITTLE FAST COMPARED TO THE ECM/GEM. WILL FORECAST ONLY SLIGHT 
RAIN CHANCES DEVELOPING FROM THE SW LATE DAY.

BETTER PRECIPITATION CHANCES ARE ANTICIPATED MON NIGHT INTO EARLY 
TUE AS A STRONG UPPER JET SETS UP ALONG THE APPALACHIAN 
CHAIN...MOISTURE AHEAD OF THE SRN STREAM SYSTEM PUSHES NE TOWARD THE 
AREA FROM THE GULF...WHILE THE NRN STREAM PUSHES A FRONTAL ZONE SE 
TOWARD THE FORECAST AREA. DESPITE THE VARIOUS FORCING 
MECHANISMS...HOWEVER...THE ECM HAS TRENDED MUCH DRIER WITH THIS 
SYSTEM...KEEPING GULF MOISTURE CONFINED TO COASTAL REGIONS AND NRN 
STREAM MOISTURE WELL N OF THE AREA. ALSO...THE HEMISPHERIC CANADIAN 
MODEL IS NOW ALSO STARTING TO FAVOR THE SPARSE MOISTURE OF THE ECM. 
WILL STILL MAINTAIN SOLID CHANCE POPS MON NIGHT INTO TUE...BUT WITH 
LIMITED QPF AT THIS POINT. THE GFS ALSO FEATURES SLIGHT INSTABILITY 
ACROSS THE SRN TIER FOR TUE...BUT ANY CONVECTION SHOULD BE VERY 
SHALLOW.

BREEZY TO WINDY CONDITIONS MAY DEVELOP TUE NIGHT THROUGH WED BEHIND 
THE PASSING UPPER TROUGH AND FRONTAL ZONE. BRIEF NW FLOW MOISTURE 
COULD WRING OUT SOME HIGH MTN SNOW SHOWERS TUE NIGHT...BUT LITTLE TO 
NO ACCUMULATION IS CURRENTLY INDICATED. MODEL DIFFERENCES PERSIST IN 
THE HANDLING OF THE NEXT SHORTWAVE RIDING DOWN TOWARD THE AREA IN NW 
FLOW LATE THU. WILL FEATURE LITTLE MORE THAN SLIGHT CHANCE MTN POPS 
LATE IN THE DAY.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
AT KCLT...GUSTY WNW WINDS WILL CONTINUE THIS AFTERNOON...THEN 
FUSTINESS WILL DIMINISH THIS EVENING. BY LATE TONIGHT LIGHT 
NORTHWEST WINDS WILL PREVAIL...WHICH WILL CONTINUE THROUGH FRIDAY 
MORNING. FEW TO SCATTERED CIRRUS WILL ARRIVE TONIGHT.

AT KAVL AND KHKY...A GRADUAL DECREASE IN GUSTY NW WINDS WILL OCCUR 
AT KAVL TONIGHT AND FRIDAY MORNING...WHILE KHKY LOSES ITS WIND 
GUSTS THIS EVENING. A FEW TO SCATTERED CIRRUS WILL INVADE FORM THE 
SOUTHWEST.

FOR UPSTATE SC SITES...WINDS SHOULD REMAIN STEADY AND FROM THE W 
BECOMING MORE NW THIS EVENING AND EVENTUALLY MORE NORTHERLY EARLY 
TOMORROW WHILE DECREASING TO WITHIN THE 5 KT RANGE. MOSTLY CLEAR 
SKIES WILL GIVE WAY TO SCATTERED HIGH CLOUDS THIS EVENING. 

OUTLOOK...VFR EXPECTED LATE FRIDAY. A GULF COAST STORM SYSTEM COULD 
SPREAD LIGHT MIXED PRECIP INTO THE REGION SATURDAY AFTERNOON INTO 
THE NIGHT. FLIGHT RESTRICTIONS COULD LINGER INTO SUNDAY. VFR MONDAY.

&&

.FIRE WEATHER...
RELATIVE HUMIDITY WILL FALL BELOW 25 PERCENT BY LATE FRIDAY MORNING 
IN NORTHEAST GA...REMAINING THERE THROUGH AFTERNOON. FUEL STICK 
MOISTURE AT CHATTOOGA THIS AFTERNOON WAS 8 GM. A RED FLAG WARNING 
WILL BE ISSUED FOR NORTHEAST GA FROM 10 AM TO 6 PM FRIDAY. SINCE 
WIND WILL NOT BE NA ISSUE FRIDAY...NO RED FLAG PRODUCTS WILL BE 
ISSUED FOR SC AND NC...WHERE BOTH WIND AND RH CRITERIA MUST BE MET.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...RED FLAG WARNING FROM 10 AM TO 6 PM EST FRIDAY FOR GAZ010-017-
     018-026-028-029.
NC...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ033-049-050-
     501-503-505.
     LAKE WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ048-052-
     053-064-065-507-509.
SC...NONE.

&&

$$
SYNOPSIS...JPT
NEAR TERM...JAT
SHORT TERM...RWH
LONG TERM...HG
AVIATION...JAT/JPT
FIRE WEATHER...