000 FXUS62 KGSP 230806 AFDGSP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 306 AM EST MON NOV 23 2009 .SYNOPSIS... A COOL AND MOIST WEDGE OF HIGH PRESSURE WILL LINGER OVER THE REGION INTO WEDNESDAY. A COLD FRONT WILL CROSS THE AREA THURSDAY... FOLLOWED BY HIGH PRESSURE LATE IN THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... CURRENT RADAR LOOP SHOWS THAT THE BULK OF THE LIGHT RAIN HAS NOW MOVED TO THE EAST...MAINLY ALONG AND EAST OF THE I-26 CORRIDOR. GIVEN RATHER MEAGER UPSTREAM RETURNS...LOOKS LIKE AFTER THIS LAST AREA OF RAIN EXITS THE CWA AREAS OF DRIZZLE WILL SETTLE IN FOR THE REMAINDER OF THE DAY. WITH THE CURRENT STATUS OF THE PRECIP SHIELD...IT APPEARS THAT THE NEAR TERM MODELS MAY BE OVERDONE IN KEEPING WIDESPREAD PRECIP ACROSS THE REGION THROUGH MUCH OF THE DAY. MID AND UPPER LEVEL SHORTWAVE WILL CONTINUE TO PUSH NORTHEASTWARD AND DAMPEN OUT TODAY. THIS LEAVES THE FA IN GENERALLY SW FLOW ALOFT WITH ANOTHER SHORTWAVE PASSING BY AND JUST CLIPPING THE NORTHERN EDGE OF THE NC MOUNTAINS. H85 WAA WILL CONTINUE THROUGH LATE MORNING...REINFORCING THE WEDGE AND ITS TRANSITION TO AN IN SITU WEDGE. LOW LEVEL MOISTURE WILL REMAIN OVER THE AREA AND STRATUS LAYER WILL STICK AROUND THROUGH TUESDAY MORNING. I HAVE PRIMARILY FOLLOWED THE SREF WHICH APPEARS TO HAVE THE BEST HANDLE ON THE CURRENT SITUATION REGARDING POPS. THEREFORE...I TRIM POPS CONSISTENTLY THROUGH THE DAY LEAVING ONLY THE NE THIRD OF THE FA IN CHANCE POPS AFTER 18Z. I/VE CONTINUED THE MENTION OF DRIZZLE EVERYWHERE BUT DO NOT HAVE ANY MENTIONABLE POPS ACROSS THE WEST. OVERNIGHT TRANSITIONS TO A DRY FORECAST WITH AREAS OF FOG AND DRIZZLE EXPECTED EVERYWHERE. I MADE VERY LITTLE CHANGE TO THE MAX TEMP FORECAST LEAVING UPPER 40S TO LOW 50S ACROSS THE FA. OVERNIGHT LOWS WILL FALL VERY LITTLE WITH VALUES IN THE LOW TO MID 40S EXPECTED. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 245 AM MONDAY...SOMEWHAT OF A TRICKY FCST DURING THE SHORT RANGE. ALTHOUGH WEAKER...CAD APPEARS TO REMAIN IN PLACE ON TUE WITH SFC RIDGING OVER THE AREA AS COASTAL LOW MOVES NORTH AWAY FROM THE AREA AND NEXT FRONTAL SYSTEM IS WELL TO OUR WEST. THERE WILL NOT BE MUCH IN THE WAY OF PRECIP...BUT LINGERING PATCHY DRIZZLE IS LIKELY DURING THE MORNING OUTSIDE OF THE MTNS. TEMPS WILL BE TRICKY AS WELL AS CLOUDS DIMINISH OVER THE WEST...BUT HOLD TIGHT IN THE EAST. HAVE BLENDED GUIDANCE OVER THE MTNS AND WENT TOWARD THE COOLER NAM ELSEWHERE. THIS GIVES AVL A HIGHER MAX THAN CLT/GSP. A BETTER CHANCE OF RAIN TUE NIGHT AS ISENTROPIC LIFT INCREASES AHEAD OF THE APPROACHING FRONT AND ANOTHER WEAK SFC LOW MOVES ALONG THE SOUTH ATLANTIC COAST. HAVE KEPT POP AT SLIGHT CHC FOR NOW WITH AREAS OF DRIZZLE AND FOG DEVELOPING IN THE CONTINUED ELY LOW LEVEL FLOW. LOWS REMAIN ABOVE NORMAL. THE COLD FRONT MOVES INTO THE AREA FROM THE WEST WED AS THE SFC LOW MOVES UP THE COAST. SLIGHT CHC POP CONTINUES DURING THE DAY WITH THE CONTINUED ISENTROPIC LIFT. PRECIP CHANCE TAPERS OFF OVER THE MTNS DURING THE AFTERNOON AS THE MOISTURE MOVES EAST. THE DAMMING REGIME FINALLY ABATES...BUT HAVE TRENDED TOWARD THE COOLER GUIDANCE WITH LIGHT RAIN AND CLOUDY SKIES. THIS PUTS HIGHS RIGHT AT NORMAL LEVELS. THE PRECIP ENDS WED NITE AS MOISTURE AND LIFT MOVE EAST OF THE AREA...BUT CLOUDS REMAIN. LOWS FALL TO A FEW DEGREES ABOVE NORMAL. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 230 AM EST MONDAY...BOTH THE ECMWF AND GFS SHOW A CLOSED UPPER LOW OVER IL ON THURSDAY MORNING. ON FRIDAY THIS LOW REACHES OH...AN ON SATURDAY THE TIP OF LONG ISLAND. BY SUNDAY AN UPPER RIDGE EXTENDS FROM THE TN VALLEY TO MI. THE ECMWF WAS PREFERRED BY HPC FOR DETAILS...AS ITS SOLUTION HAS BEEN MORE CONSISTENT. ON THURSDAY A PAIR OF COLD FRONTS WILL MOVE ACROSS THE SOUTHERN APPALACHIANS...ONE EARLY IN THE DAY...REINFORCED BY THE SECOND LATE IN THE DAT. THE FIRST FRONT WILL CLEAR THE LEE OF THE MOUNTAINS OF LOW LEVEL MOISTURE...WHILE THE SECOND FRONT WILL INTRODUCE A COLD AND MOIST UPSLOPE FLOW TO THE MOUNTAINS ON THURSDAY NIGHT. SNOW LEVELS WILL FALL TO THE VALLEY FLOORS THURSDAY NIGHT. WITH SUCH A STRONG UPPER LEVEL SYSTEM...AND A MOISTURE FETCH STRETCHING BACK TO THE GREAT LAKES...SNOW IS EXPECTED TO EXTEND AS FAR EAST AS THE BLUE RIDGE THURSDAY NIGHT...THOUGH NOT IN QUANTITIES SEEN ON THE TN BORDER. WINDS MAY APPROACH ADVISORY CRITERIA IN THE NC MOUNTAINS THURSDAY NIGHT...AND REMAIN THERE INTO SATURDAY. ON FRIDAY SNOW LEVELS RISE TO MID ELEVATIONS...WITH SOME RETREAT FROM THE BLUE RIDGE AS THE UPPER SYSTEM PASSES. SNOW LEVELS FALL AGAIN FRIDAY NIGHT...BUT BY THAT TIME MOISTURE DECREASES TO THE POINT THAT ONLY SMALL POPS WILL BE CARRIED ALONG THE TN BORDER. SNOW ENDS BY SATURDAY MORNING...WITH WINDS DIMINISHING AS THE PRESSURE GRADIENT RELAXES. SUNDAY FEATURES DRY HIGH PRESSURE. TEMPERATURES WILL FALL TO SEVERAL CATEGORIES BELOW NORMAL ON FRIDAY IN COLD ADVECTION... DESPITE A DOWNSLOPE COMPONENT IN THE LEE OF THE MOUNTAINS. AS HEIGHTS RISE WITH THE PASSAGE OF THE UPPER LOW...TEMPERATURES WILL WARM TOWARD NORMAL VALUES SATURDAY...REACHING NORMAL ON SUNDAY. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... AT KCLT...EXPECT PREVAILING IFR CIGS AT THE BEGINNING OF THE TAF PERIOD BUT WILL TEMPO IN SCT AS THE OBS TREND HAS BEEN FOR THE SUB 1 KFT DECK TO COME AND GO. INTERMITTENT LIGHT RAIN WILL PERSIST THROUGH THE REMAINDER OF THE MORNING PER UPSTREAM RADAR TRENDS AND SHORT TERM MODELS. WILL TRANSITION TO DZ AT 17Z THOUGH IFR CIGS ARE EXPECTED TO LAST THROUGH THE ENTIRE TAF PERIOD. ALL GUIDANCE POINTS TO FOG DEVELOPING LATE TONIGHT AND EARLY TUESDAY MORNING SO I BRING IN 2SM AT 03Z. WINDS WILL BE NE THROUGH THE MAJORITY OF THE TAF PERIOD WITH A TURN CLOSER TO NORTHERLY DURING THE LATE NIGHT. MARGINAL LLWS THREAT IS STILL THERE THOUGH I WILL NOT INCLUDE IT AS MODELS PRESENT A MIXED SOLUTION AT BEST BETWEEN 06-12Z. ELSEWHERE...WILL START THE TAFS WITH IFR CIGS EXCEPT AT KAVL AND KHKY WHICH WILL GO THAT WAY BY 09Z. CURRENT RADAR SHOWS THAT LIGHT RAIN IS BEGINNING TO TAPER OFF FROM THE SW AND SHOULD BE REPLACED WITH DZ EVERYWHERE BY LATE MORNING AND EARLY AFTERNOON. COULD BE PERIOD AROUND DAYBREAK WHERE VIS COMES DOWN TO AROUND 2-3 MILES BUT SHOULD REBOUND FOR THE REMAINDER OF THE MORNING. EXPECT NE FLOW THROUGH THE DAY WHICH BECOMES MORE NORTHERLY DURING THE LATE NIGHT HOURS. ALSO...I DO BRING IN SOME 2-3 MILE VIS IN THE 03-04Z TIME FRAME PER GUIDANCE TRENDING DOWNWARD. OUTLOOK...MODEL GUIDANCE SHOWS IMPROVEMENT TUESDAY BUT MOST LIKELY AT BEST MVFR SHOULD BE EXPECTED UNTIL WEDNESDAY. A COLD FRONT WILL BRING WINDY CONDITIONS ON THURSDAY AND A FEW RESTRICTIONS IN SHOWERS IN THE MOUNTAINS. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JAT NEAR TERM...BSH SHORT TERM...RWH LONG TERM...JAT AVIATION...BSH/NED