000 FXUS62 KGSP 042336 AFDGSP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 636 PM EST THU DEC 4 2008 .SYNOPSIS... A COLD FRONT WILL CONTINUE TO MOVE INTO THE FORECAST AREA FROM THE WEST THROUGH THIS EVENING...BEFORE PUSHING EAST OF THE REGION BY FRIDAY MORNING. ANOTHER FAST MOVING COLD FRONT WILL CROSS THE WESTERN CAROLINAS SUNDAY MORNING...WITH HIGH PRESSURE BUILDING IN BEHIND THE FRONT THROUGH MONDAY. && .NEAR TERM /THROUGH FRIDAY/... DID AN UPDATE TO POP/WX TO TAKE CURRENT RADAR TRENDS INTO ACCOUNT. NO OTHER CHANGES TO FORECAST SO FAR. THE MODELS DO NOT APPEAR TO HAVE INITIALIZED PARTICULARLY WELL THE SHORT WAVE MOVING FROM AL INTO GA THIS AFTERNOON ALONG WITH THE AREA OF LIGHT TO MODERATE RAIN THAT IT IS SUPPORTING. THE SHORT WAVE SHOULD CROSS THE FORECAST AREA BETWEEN 21Z AND 03Z ALONG WITH SOME UPPER DIVERGENCE. ALTHOUGH THE PRECIP AREA CONTINUES TO SLOWLY BUT GRADUALLY SINK AS THE WAVE DAMPENS...IT SHOULD HAVE ENOUGH FORCING TO BRING THE PRECIP AREA ACROSS NE GEORGIA AND INTO THE UPSTATE THROUGH EARLY EVENING. SO...A VERY HIGH POP WILL BE CARRIED THERE AND IT TAPERS OFF TO THE CHANCE RANGE AS YOU GO EAST WITH THE UNCERTAINTY THAT IT WILL HOLD TOGETHER. THE FRONT SHOULD PUSH ACROSS THE REGION THIS EVENING...WITH THE UPPER WAVE EXITING AROUND 03Z...WHICH SHOULD BRING AN END TO THE PRECIP ACROSS ALL BUT THE SRN/ERN FRINGE ZONES. A BLEND OF THE GUIDANCE WAS USED FOR LOW TEMPS OVERNIGHT. ON FRIDAY...THE OPERATIONAL MODELS HAVE THE FRONT AND UPPER WAVE WELL TO THE EAST WHILE THE NEXT SYSTEM APPROACHES FROM THE WEST...BUT DOES NOT REACH THE MOUNTAINS UNTIL AFTER SUNSET. THIS WILL SUPPORT DRY HIGH PRESSURE BUILDING IN FROM THE WEST. CLEARING SKY AND DOWNSLOPE EAST OF THE MOUNTAINS SHOULD ALLOW TEMPS TO RISE A BIT WARMER THAN PREVIOUSLY THOUGHT OVER THE NC PIEDMONT SO AN UPWARD ADJUSTMENT WAS MADE THERE...BUT OVERALL TEMPS WILL BE BELOW NORMAL. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... AS OF 215 PM THURSDAY...WEAK SFC RIDGING WILL TEMPORARILY BUILD INTO THE REGION FRI NITE PROVIDING FAIR AND CHILLY CONDITIONS. CWFA TO COME UNDER GENERAL ASCENT AREA ALONG FRONT SIDE OF APPROACHING L/WV TROUGH AND RIGHT EXIT REGION OF UPPER JET ON SATURDAY...BUT DEEPER RH...ALONG AND AHEAD OF ATTENDANT COLD FRONT...IS PROGGED TO QUICKLY BRUSH BY THE NW CWFA DURING THE AFTERNOON. LIGHT MODEL RESPONSE OFF THE OP GFS LOOKS TO BE THE WORST CASE SCENARIO...WITH EVEN THE 09 UTC SREF POP ONLY SLIGHT CHANCE. SO...WILL MAINTAIN GOING 20 POP ALONG AND NORTH OF I-40 AND MENTION LIGHT RAIN AND ELEVATION DEPENDENT LIGHT SNOW. IN CONCERT WITH S/WV ENERGY ROTATING THRU BASE OF L/WV...DEVELOPING UPSLOPE NW FLOW AND INCREASING CAA WILL PRODUCE SCATTERED TO NUMEROUS ACCUMULATING SNOW SHOWERS ACRS THE WESTERN NC MTNS SATURDAY NIGHT BEFORE DIMINISHING SUNDAY MORNING. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 240 PM THURSDAY...BOTH THE ECMWF AND GFS INDICATE THAT CANADIAN HIGH PRESSURE WILL BECOME CENTERED ACROSS THE MID ATLANTIC MONDAY MORNING. LIGHT WINDS...MOSTLY CLEAR SKY COVER...AND LOW DEWPOINTS WILL LIKELY RESULT IN MIN TEMPERATURES 5 TO 10 DEGREES BELOW NORMAL. TEMPERATURES WILL REMAIN BELOW NORMAL DURING THE DAY AS SFC HIGH CONTINUES TO RIDGE ACROSS THE WESTERN CAROLINAS AND CLOUDS THICKEN. BEGINNING TUES MORNING...SFC LOW PRESSURE WILL LIKELY DEEPEN OVER THE LOWER MISSISSIPPI RIVER VALLEY AS A DEEP TROF AMPLIFIES IN THE LEE OF THE ROCKIES. DEEP FORCING AND MOISTURE WILL SPREAD ACROSS THE REGION TUESDAY MORNING AND INCREASE THROUGH THE DAY. TEMPERATURES AND THICKNESSES ACROSS THE MTNS AND PORTIONS OF THE FOOTHILLS/PIEDMONT MAY RESULT IN AN INITIAL PERIOD OF WINTER PRECIP. HOWEVER...WAA AND DIURNAL TEMPERATURES WILL LIMIT THE WINTER PRECIP THE THE HIGH ELEVATIONS BY MID MORNING TUES. RAINFALL RATES SHOULD GRADUALLY INCREASE INTO THE AFTERNOON WITH INCREASES IN UPSLOPE FLOW AND ISENTROPIC LIFT. TUES NIGHT...THE H5 TROF WILL SHARPEN AND POSSIBLY CLOSE OFF OVER THE DEEP SOUTH...DEEPENING THE SFC LOW ACROSS AL/GA. AS THE LOW DEVELOPS...ATLANTIC AND GULF MOISTURE WILL SURGE ACROSS THE FA WITH DEEP LIFT. FORECAST SOUNDINGS AND EXPECTED SURFACE TEMPERATURES SUPPORT PRECIPITATION FALLING A RAIN...WITH A FEW AREAS OF HIGH ELEVATION MIX WITH SN. IT IS TOO EARLY TO DETERMINE THE STORM TOTAL RAINFALL...HOWEVER...IT APPEARS THAT THE MAJORITY OF THE REGION WILL SEE AMOUNTS EXCEED AN INCH BETWEEN TUES AND WEDS. WED NIGHT...LOW PRESSURE WILL RACE NE ALONG THE ATLANTIC COAST...LEAVING MOISTURE AND CAA ACROSS THE MTNS. I WILL FORECAST A PERIOD OF NWFS WED NIGHT ACROSS THE NC MTNS...HOWEVER...QPF APPEARS VERY LIMITED WED NIGHT. HIGH PRESSURE WILL RETURN TO THE REGION ON THURSDAY...CONDITIONS WILL REMAIN COOL WITH GUSTY WINDS. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... SHOWERS ARE DISSIPATING AS THEY MOVE EAST ACROSS THE AREA. MVFR CIGS HAVE NOT MADE IT EAST OF KAVL TO KGSP LINE. EXPECT LOW VFR CIGS TO REMAIN EAST OF THERE...BUT QUESTIONABLE IF ANY MVFR CIGS WILL MAKE IT EASTWARD. THEREFORE...HAVE KEPT KCLT AND KHKY AT LOW VFR THRU THE EVENING WITH MVFR WRN SITES. LOW LEVEL MOISTURE DOES MOVE OUT LATE TONIGHT...SO ALLOW SOME AREAS TO LOSE THE LOW VFR CIGS...BUT OTHERS KEEP IT ALL NITE. WITH PRECIP REMAINING LIGHT...DO NOT EXPECT ANY MVFR VSBY. EXPECT CIGS TO END BY EARLY FRI MORN AT THE LATEST WITH ONLY SCT CLOUDS THE REST OF THE DAY. WEST SOUTHWEST WINDS BECOME NORTHWEST BEHIND THE APPROACHING COLD FRONT. WINDS BECOME NORTHEAST AS HIGH PRESSURE BUILDS IN LATE TOWARD MORNING. COULD BE SOME LOW END GUSTS...BUT TIMING UNCERTAIN AND TIME OF FRONTAL PASSAGE NOT AS CONDUCIVE. LIGHT NORTHEAST WINDS CONTINUE FRIDAY. OUTLOOK...A COLD FRONT WILL CROSS THE REGION SAT WITH A FEW SHOWERS AND CIG/VSBY RESTRICTIONS PSBL INTO SUN MRNG. HI PRES REBUILDS SUN NIGHT-MON. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...SBK NEAR TERM...PM/RWH SHORT TERM...CSH LONG TERM...NED AVIATION...PM/RWH