000
FXUS62 KGSP 210229
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
929 PM EST THU NOV 20 2008

.SYNOPSIS...
COLD NORTHWEST FLOW IN THE WAKE OF A COLD FRONT WILL CONTINUE OVER
THE AREA THROUGH FRIDAY. A STRONG AREA OF HIGH PRESSURE WILL THEN
MOVE OVER THE SOUTHEAST EARLY SATURDAY...AND REMAIN THE DOMINANT
WEATHER FEATURE THROUGH THE WEEKEND. ANOTHER COLD FRONT IS THEN
EXPECTED TO MOVE OVER THE CAROLINAS EARLY NEXT WEEK FOLLOWED BY
ANOTHER RIDGE OF HIGH PRESSURE BUILDING IN TOWARDS THE MIDDLE OF
NEXT WEEK.

.NEAR TERM /THROUGH FRIDAY/...
SHORT WAVE AOLFT CONTINUES MOVING TOWARD THE SOUTHERN APPALACHIANS
TO AFFECT THE AREA OVERNIGHT...CROSSING THE REGION QUICKLY FRI MRNG.
UPPER DIVERGENCE STILL EXPECTED ALONG AND E OF THE BLUE RIDGE LATE
TONIGHT INTO EARLY FRI AS A 120 KT JET STREAK CROSSES THE MTNS. WITH
MID LEVEL MOISTURE AHEAD OF WAVE COMBINES WITH GOOD NW FLOW...
EXPECT INCREASING CHANCE SNOW SHOWERS ACROSS MTNS...ESP ALONG TN
BORDER. QPF SHOULD RUN CLOSE TO 1/10 INCH IN BEST UPSLOPE AREAS AND
SNOW RATIOS OF 15 TO 1 ARE LIKELY AFTER 09Z. DUE TO SHORT DURATION
KEPT EARLIER SNOWFALL TOTALS OF 1 TO 2 INCHES WITH WINTER WEATHER
ADVISORY FROM SWAIN TO AVERY ALONG TN BORDER.

AS THE REINFORCING COLD AIR MOVES IN LATE TONIGHT AND NW DOWNSLOPE
FLOW INCREASES EAST OF MTNS...A MAXIMA OF MID LEVEL FRONTOGENESIS
SHOULD FORM ALONG THE BLUE RIDGE. THIS MAY KEEP CLOUDINESS UP
OUTSIDE HIGH TERRAIN THROUGH FRI MORNING...AND POSSIBLY PROMOTE A
STRONGER DOWNWARD MOTION COMPONENT ON THE COLD SIDE. WINDY TO VERY
WINDY CONDITIONS MAY DEVELOP ACROSS THE REGION AS MIXING SETS IN. A
STRONG CORE OF MID LEVEL WINDS WILL TRANSIT THE REGION DURING THE
AFTERNOON AS MIXING REACHES UP TO NEARLY 800 MB. A LAKE WIND
ADVISORY WILL LIKELY BE NEEDED...WITH PSBL WIND ADVSRY FOR MTNS FRI
AFTN.

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
AS OF 200 PM THURSDAY...OUR AREA REMAINS IN NW FLOW ALOFT FRIDAY
NIGHT AS AN UPPER TROUGH DEPARTS THE EAST COAST...AND A LOW
AMPLITUDE RIDGE CROSSES THE MS VALLEY. THIS RIDGE CROSSES THE
SOUTHERN APPALACHIANS ON SATURDAY...WHILE A SHORTWAVE TROUGH
UPSTREAM MOVES INTO THE OH VALLEY. THE SHORTWAVE MOVES ACROSS OUR
AREA SATURDAY NIGHT...FOLLOWED BY MORE NW FLOW SUNDAY...AND A LARGE
AMPLITUDE UPPER RIDGE ON SUNDAY NIGHT.

A LARGE...DRY SURFACE RIDGE WILL BUILD EAST FRIDAY NIGHT ACROSS THE
SOUTHERN APPALACHIANS...DECREASING THE GRADIENT OVER OUR AREA. ON
SATURDAY AFTERNOON AND EVENING...MID TO UPPER LEVEL CLOUDS
ACCOMPANYING THE UPPER SHORTWAVE WILL MOVE OVER WESTERN NC AND
NORTHERN SC...WITH CLEAR SKIES RETURNING BY MORNING. THE SURFACE
RIDGE MOVES TO THE COAST BY SUNDAY EVENING...WITH RETURN FLOW FROM
THE GULF SPREADING MOISTURE TO THE MOUNTAINS BEFORE DAWN ON MONDAY.

TEMPERATURES WILL CLIMB FROM BELOW MID WINTER AVERAGES ON
SATURDAY...TO SLIGHTLY ABOVE MID WINTER VALUES ON SUNDAY...AS
HEIGHTS RISE ALOFT.

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 130 PM THURSDAY...MODELS ARE CONSISTENT ON YET ANOTHER DIGGING
S/W OVR THE GREAT LAKES INTO THE MID ATLANTIC REGION MONDAY INTO
TUESDAY. AN ASSOCIATED COLD FRONT WILL CROSS THE FA MONDAY
AFTN/EVE...WITH LIMITED MOISTURE. BOTH THE 12Z GFS AND 00Z ECMWF
HAVE THE GENERAL IDEA FOR THIS PATTERN. HOWEVER...THE GFS CONTS TO
BE LESS AMPLIFIED/MORE PROGRESSIVE THAN THE ECMWF. IF THE ECMWF IS
CLOSER TO REALITY...A PROLONGED NW FLOW SNOW EVENT WOULD BE ON TAP.
HOWEVER...EVEN THE ECMWF HAS LTL QPF ACRS THE SRN APPALACHIAN RGN
AFTER 12Z TUESDAY. WITH ALL THAT SAID...I MADE LITTLE CHANGE TO POPS
FOR THE FROPA AND SUBSEQUENT NW FLOW PRECIP USED HPC GUIDANCE AS
BASIS. A 30 PCT POP OR SO WITH FROPA STILL IS IN LINE WITH
UNCERTAINTY ASSOC W/ TIMING AND MOISTURE. OVERALL QPF SHOULD BE ON
THE LIGHT SIDE. BELOW NORMAL TEMPS AND DRY CONDITIONS ARE EXPECTED
FROM MIDWEEK INTO FRIDAY...AS POLAR HIGH SETTLES OVR THE SOUTHEAST
STATES UNDER CONTINUED NWLY FLOW ALOFT.

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
PRESSURE GRADIENT WILL INCREASE TONIGHT AS A COLD FRONT PUSHES SE
ACROSS THE AREA...THEN ARCTIC HIGH PRESSURE BUILDS FROM THE W FRI.
AS SYSTEM MOVES IN LATE TONIGHT INCREASING MOISTURE SHOULD PRODUCE
SCATTERED TO NUMEROUS MOUNTAIN SNOW SHOWERS. MODELS STILL SHOW MOST
OF THE SNOW NEAR THE TN BORDER SO WILL KEEP VCNTY MENTION FOR KAVL
AFTER 06Z. LOW LEVEL MOISTURE SHOULD ALSO BRING TEMPO MVFR CIGS TO
KAVL AROUND DAYBREAK. VFR CLOUDS EXPECTED SE OF MTNS WITH BEST
CHANCE OF FLURRIES/ISOLATED SNOW SHOWERS FROM KHKY TO KCLT TOWARD
DAYBREAK...BUT CHANCE TOO LOW TO MENTION IN TAF.

WINDS MAIN CONCERN FRI AS DOWNWARD FORCING COMBINES WITH DAYTIME
MIXING FOR NW GUSTS OF 20-25 KT BY LATE MORNING...30-35 KT IN THE
AFTN...PSBLY HIGHER KAVL.

OUTLOOK...VFR CONDITIONS EXPECTED ACROSS THE REGION FRIDAY NIGHT
THROUGH SUNDAY AS STRONG DRY HIGH PRESSURE SETTLES IN. A COLD FRONT
WILL MOVE THROUGH THE AREA MON WITH A CHANCE OF SHOWERS AND CIG/VSBY
RESTRICTIONS.

.FIRE WEATHER...
A REINFORCING SHOT OF COLD AND DRY AIR WILL MOVE INTO THE REGION
TONIGHT THROUGH FRIDAY. WINDY CONDITIONS ARE EXPECTED ACROSS THE
WESTERN CAROLINAS AND NORTHEAST GEORGIA FRIDAY...AND DRY AFTERNOON
RELATIVE HUMIDITIES ARE EXPECTED ACROSS FOOTHILL AND PIEDMONT
SECTIONS. A FIRE WEATHER WATCH WILL BE ISSUED ACROSS NORTHEAST
GEORGIA AND UPSTATE SOUTH CAROLINA OUTSIDE OF THE MOUNTAINS...AS RH
VALUES COULD FLIRT WITH 25 PERCENT FOR A FEW HOURS AND WINDS GUST
BETWEEN 20 AND 30 MPH. A FIRE DANGER STATEMENT WILL BE ISSUED FOR
THE NC FOOTHILLS AND PIEDMONT WHERE RH VALUES WILL BE IN THE UPPER
20S TO LOWER 30S...BUT WITH WINDS GUSTING ABOVE 30 MPH DURING THE
AFTERNOON.

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY
     AFTERNOON FOR GAZ018-026-028-029.
NC...WINTER WEATHER ADVISORY UNTIL 12 PM EST FRIDAY FOR NCZ033-
     048052.
SC...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY
     AFTERNOON FOR SCZ004014-019.

SYNOPSIS...JPT
NEAR TERM...HG/RB
SHORT TERM...JAT
LONG TERM...ARK
AVIATION...HG/RB
FIRE WEATHER...