000 FXUS62 KGSP 082335 AFDGSP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 635 PM EST SUN NOV 8 2009 .SYNOPSIS... A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH MONDAY. ABUNDANT MOISTURE ASSOCIATED WITH IDA IS THEN EXPECTED TO MOVE OVER THE CAROLINAS AND NORTH GEORGIA AHEAD OF A COLD FRONT ON TUESDAY. THE FRONT WILL CROSS THE AREA LATE TUESDAY INTO EARLY WEDNESDAY. HIGH PRESSURE WILL THEN RETURN FOR THE LATTER PART OF THE WEEK. && .NEAR TERM /THROUGH MONDAY/... UPPER RIDGE AXIS SLIDES EAST OF THE AREA TONIGHT PRODUCING SLY FLOW AS SHORT WAVES APPROACH FROM THE WEST. AT THE SFC...THE CENTER OF HIGH PRESSURE MOVES EAST BUT RIDGING REMAINS OVER THE AREA KEEPING WINDS LIGHT. CIRRUS WILL SLOWLY INCREASE OVER THE AREA BUT REMAIN THIN. LOWS END UP NEAR NORMAL MOST LOCATIONS...BUT ABOVE NORMAL IN THE THERMAL BELT AREAS OF THE UPSTATE. THERE IS SOME EASTWARD MOVEMENT OF THE UPPER FEATURES MONDAY...BUT BEST ENERGY REMAINS TO OUR WEST. SFC HIGH PRESSURE RIDGE WEAKENS BUT REMAINS CENTERED OVER NC. THIS ALLOWS A SLIGHT GRADIENT INCREASE AS THE TROPICAL APPROACHES FROM THE SOUTH...BUT WINDS REMAIN GENERALLY LIGHT. INCREASE IN CLOUDS LATE IN THE DAY FROM THE WEST AND SLIGHTLY LOWER THICKNESSES WILL LEAD TO A COOLING TREND FOR HIGHS. HOWEVER... THEY WILL STILL BE AS MUCH AS 10 DEGREES ABOVE NORMAL. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... AS OF 230 PM EDT SUNDAY...THE MODELS BRING A SOUTHERN STREAM SHORTWAVE EAST ACROSS THE LOWER MS RIVER VALLEY MONDAY NIGHT...WITH THE GFS REACHING THE AL/MS BORDER TUE MORNING...WHILE THE NAM IS BACK IN SOUTHERN ARKANSAS. BY TUE EVENING THE GFS SHORTWAVE IS IN EAST TN WHILE THE NAM IS BACK IN WEST TN. TO COMPLICATE THINGS FURTHER...MOISTURE ASSOCIATED WITH TROPICAL SYSTEM IDA IS EXPECTED TO BE DRAWN NORTH INTO THE GULF STATES MONDAY NIGHT. SLIGHT CHANCE POPS WILL BE CARRIED MONDAY EVENING...WITH POPS INCREASING TO LIKELY IN NORTHEAST GA AND CHANCE ELSEWHERE OVERNIGHT. THE GFS FASTER TO SPREAD DEEP MOISTURE... ISENTROPIC UPGLIDE...AND UPSLOPE FLOW INTO THE SOUTHEAST FACING BLUE RIDGE ESCARPMENT OF NORTHEAST GA AND UPSTATE SC ON TUE...BUT EITHER WAY IT LOOKS LIKE A WET DAY...AND CATEGORICAL POPS WILL BE CARRIED IN THE SOUTHWEST PORTION OF THE AREA...TRENDING DOWNWARD TO LIKELY IN THE CENTRAL PORTION...AND CHANCE IN THE FAR NORTHEAST. ALTHOUGH DETAILS OF THE END OF THE EVENT VARY BY MODEL...SOME DRYING FROM THE SOUTHWEST IS INDICATED WEDNESDAY NIGHT. USING A CONSERVATIVE APPROACH...LIKELY POPS WILL BE MAINTAINED OVER MOST OF THE AREA... INCLUDING MUCH OF THE TN BORDER...WHERE UPSLOPE FLOW WILL FOLLOW THE PASSAGE OF THE SURFACE LOW. SOME DECREASE IN POPS IS POSSIBLE ALONG THE BLUE RIDGE ESCARPMENT AS FLOW BECOMES DOWNSLOPE. THE DIURNAL TEMPERATURE RANGE WILL BE LIMITED BY CLOUD COVER AND MOISTURE...AND AN ATTEMPT WAS MADE TO KEEP FORECAST VALUES WITH THE SUBSTANTIAL SPREAD OF THE MODEL GUIDANCE. AT THIS POINT THE FORECAST WILL CARRY UP TO THREE INCHES OF RAINFALL ALONG THE GA/SC BLUE RIDGE ESCARPMENT...PER HPC GUIDANCE. THIS VALUE COULD EASILY BE HIGHER OR LOWER DEPENDING ON HOW FACTORS COME TOGETHER....BUT THERE DOES SEEM TO BE BETTER CONSENSUS BACKING HIGHER NUMBERS...AND HEAVY RAINFALL WILL BE MENTIONED IN THE HAZARDOUS WEATHER OUTLOOK. ANOTHER POTENTIAL HAZARD WILL BE WINDS APPROACHING ADVISORY CRITERIA AT HIGHER ELEVATIONS ON TUESDAY...BUT CONFIDENCE IS LOWER THAN IT IS FOR HEAVY RAINFALL. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... AS OF 200 PM SUNDAY...WITH CONSIDERABLE UNCERTAINTY...A LOW OR TROUGH WHICH CONTAINS THE REMNANT CIRCULATION AND MOISTURE OF IDA SHOULD BE IN PLACE SOMEWHERE ALONG THE SE COAST OF THE U.S. WED NIGHT. THE OPERATIONAL GFS APPEARS TOO DEEP...TOO FAR INLAND...AND TOO FAR NE WITH THE TRANSITIONING SYSTEM WED NIGHT. WILL THUS SHY AWAY FROM THE WRAP AROUND MOISTURE AND COLD PROFILES ACROSS NW NC FOR WED NIGHT...AND LEAN TOWARD THE DRIER SREF/GFS ENSEMBLE MEAN SOLUTIONS AT THE START OF THE PERIOD. ADDITIONAL DRYING IS EXPECTED THROUGH THU AS SFC HIGH PRES BUILDS DOWN FROM THE NW. A BROAD RIDGE OF HIGH PRESSURE WILL THEN MOVE OVER THE FORECAST AREA FROM THE WEST LATE THU INTO THE WEEKEND. SOME SOUTHERLY RETURN FLOW MOISTURE WILL GRADUALLY DEVELOP INTO THE SRN APPALACHIANS AROUND THE SFC HIGH PRES...BUT THIS WOULD WARRANT LITTLE MORE THAN MTN SLIGHT CHANCE POPS SAT AFTN AND LOW END SLIGHT CHC TO CHC POPS SUNDAY AFTN. TEMPS WILL BE NEAR NORMAL EARLY IN THE PERIOD...BECOMING SLIGHTLY ABOVE NORMAL OVER THE WEEKEND. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... AT KCLT AND ELSEWHERE...LGT/VRB WND TO CALM OVRNGT...WITH A FEW CIRRUS STREAMING OVRHD. BASED ON THE TRENDS IN SFC OBS AND A LOOK AT 18Z SOUNDINGS TO THE SOUTH...VSBY RESTRICTIONS DO NOT LOOK LIKELY...DESPITE GOOD RADIATIONAL COOLING CONDITIONS. KAND AND KAVL HAVE THE HIGHEST CHANCE OF SOME FOG...BUT WILL NOT ADD MENTION IN TAFS ATTM. MONDAY...AS HURRICANE IDA MOVES INTO THE GULF...WNDS WILL BCM NELY (SELY AT KAVL)...BUT SHUD RMN RATHER LGT THRU THE AFTN. CIRRUS/HIGH CLOUDS WILL INCR IN COVERAGE...THICKEN AND BEGIN TO LWR SOMEWHAT DURING THE DAY. OUTLOOK...A COLD FRONT WILL APPROACH FROM THE WEST...AS IDA APPROACHES FROM SOUTH INVOF CENTRAL GULF OF MEXICO. THERE IS UNCERTAINTY ON EXACTLY HOW THE TWO SYSTEMS WILL POSITION THEMSELVES FROM LATE MONDAY NGT THRU WEDNESDAY WRT THE CAROLINAS. HOWEVER...IT IS EXPECTED THAT AN INCREASING CHC OF SHWRS AND CIG/VSBY RESTRICTIONS ARE ON TAP ACRS THE AREA DURING THIS PERIOD. THE FRONT SHOULD MOVE EAST ON WEDNESDAY WITH VFR CONDITIONS RETURNING. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JPT NEAR TERM...RWH SHORT TERM...JAT LONG TERM...HG AVIATION...ARK