FXUS62 KGSP 101534 AFDGSP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1034 AM EST WED MAR 10 2010 .SYNOPSIS... MOISTURE WILL GRADUALLY MOVE INTO THE AREA FROM THE SOUTHWEST TODAY AND TOMORROW AS A BROAD LOW PRESSURE SYSTEM APPROACHES THE CAROLINAS FROM THE WEST TOWARDS THE END OF THE WEEK. THIS LOW WILL LINGER OVER THE REGION THROUGH THE WEEKEND AND FINALLY MOVE OFFSHORE BY EARLY NEXT WEEK. IN ITS WAKE...HIGH PRESSURE WILL BUILD BACK OVER THE AREA FROM THE NORTHWEST. && .NEAR TERM /THROUGH TONIGHT/... THE LATEST NAM HAS SHIFTED IT/S AREA OF STRONG UPPER DIVERGENCE FARTHER TO THE SOUTH. WHILE IT/S STILL MUCH TOO FAR NORTH WITH PCPN TODAY...THIS TREND AT LEAST MATCHES REALITY A LITTLE BETTER. I PREFER THE SREF PCPN FIELDS. THIS IS JUST A HAIR NORTH OF THE GFS...BUT IS MUCH FURTHER SOUTH THAN THE NAM...WITH THE HEAVIEST PCPN OVER NE GA...THE WRN UPSTATE AND THE EXTREME SOUTHERN NC MTNS. I/VE CUT BACK POPS OVER THE NRN ZONES TO MATCH CURRENT TRENDS AND THE FAVORED MODEL SOLUTIONS. THE ATLANTA OFFICE HAS JUST ISSUED A FLOOD WATCH FOR MOST OF NRN GA...RIGHT UP TO OUR FORECAST AREA. I/M NOT PLANNING TO ISSUE A WATCH...BUT THEY HAVE HAD MUCH MORE RAIN THIS MORNING...AND OUR CWA BOUNDARY ACTUALLY MAKES FOR A PRETTY GOOD BREAK POINT. WE/LL SEE HOW MUCH FALLS WITH THIS FIRST BATCH. A SECOND AREA OF RAIN IS EXPECTED TO MOVE ACROSS THE REGION LATE TNGT AND THU...AND IF AN INCH OR SO FALLS TODAY OVER THE SW ZONES...THEN WE MAY ENTERTAIN A WATCH. PRECIP SHOULD TAPER OFF A BIT OVERNIGHT AS H5 SHRTWAVE RIDGE MIGRATES ACROSS THE AREA AND TEMPS COOL DOWN INTO THE 40S...BUT AS A SHORTWAVE TROF ROTATES AROUND THE UPPER LOW TO THE W AND UPPER LEVEL DIVERGENCE INTENSIFIES...EXPECT PRECIP RATES TO PICK UP LATE TONIGHT. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... AS OF 3 AM WEDNESDAY...EXPECTING UNSETTLED WEATHER OVER THE FORECAST AREA THRU THE END OF THE WEEK. THE SHORT TERM FCST PICKS UP AT 12Z ON THURSDAY WITH THE H5 LOW SLOWLY MOVING EASTWARD TO THE OHIO VALLEY BY LATE SATURDAY. THE ORIENTATION OF THE LOW KEEPS THE FORECAST AREA IN CYCLONIC SW FLOW ALOFT. IN THE LOW LVLS...PERSISTENT SOUTHERLY FLOW WILL CONTINUE TO TRANSPORT GULF MOISTURE OVER THE SE STATES. A STRONG UPPER LEVEL JET ALONG THE SOUTHERN TIER STATES WILL ADD LIFT ACROSS OUR REGION INTO THURS. THE GFS/NAM/ECMWF/GEM ALL INDICATE POTENTIAL FOR GULF CONVECTION TO OUR SOUTH (POTENTIALLY ROBBING THE FA OF MOISTURE) ON THURSDAY AFTERNOON. EXCESSIVE QPF SHOULD BE HELD IN CHECK BY STRONGER CONVECTION TO OUR SOUTH. AT PRESENT...I HAVE NO MORE THAN AN INCH OF TOTAL QPF FOR THE DURATION OF THE FCST. TEMPS SHOULD MODERATE UNDER CLOUDS/PRECIP (LOWS IN THE M-U40S AND HIGHS IN THE UPR 50S OVER THE MTNS TO LWR 60S OVER THE PIEDMONT). FOR THURSDAY NIGHT AND FRIDAY...A DRY SLOT WILL PUSH INTO THE REGION FROM THE SW. THUS...POP GRIDS REFLECT A POTENTIAL BREAK IN PRECIP EARLY FRIDAY. ANOTHER SHORTWAVE WILL ROTATE AROUND THE UPPER LOW FRIDAY AFTERNOON...AND DAMPEN AS IT MOVES OVER THE SOUTHERN APPALACHIANS. LATEST MODEL RUNS CONTINUE TO TREND A BIT SLOWER WITH THE MID LVL SHORTWAVE AND ASSOCIATED COLD FRONT CROSSING THE OH/TN VALLEYS FRI AFTERNOON/EVENING. THE 00Z GFS SOUNDINGS STILL INDICATE 500+ J/KG OF SBCAPE IN GA AND THE UPSTATE...ALTHOUGH THE 00Z ECMWF IS NOT QUITE AS BULLISH WRT SBCAPE. IF THE LOW REMAINS EAST OF CURRENT PROGS AND THE COLD FRONT CAN REACH THE FCST AREA BY FRI EVENING THERE COULD BE A WEAK TO MODERATELY FORCED LINE OF TSTMS PUSHING IN FROM THE WEST. SHEAR PROFILES ARE MODEST AT BEST THOUGH...AS FLOW BECOMES MORE UNIDIRECTIONAL...AND RATHER WEAK. SO SEVERE POTENTIAL REMAINS LOW OVERALL. IN ANY CASE...I KEPT LIKELY POPS WITH AT LEAST A SLIGHT CHANCE OF THUNDER FROM FRI AFTERNOON THRU SAT MORNING. TEMPS WILL BE MILD AHEAD OF THE FRONT WITH LOWS IN THE 40S OVER THE MTNS AND 50S OVER THE PIEDMONT AND HIGHS IN THE 60S TO LWR 70S. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... AS OF 230 AM WEDNESDAY...THE MEDIUM RANGE FCST BEGINS 00Z SUNDAY WITH THE H5 LOW CENTERED OVER EASTERN TN/NORTHERN GA REGION AND ANOTHER CLOSED H5 LOW DEVELOPING OVER THE WESTERN ROCKIES. EASTERN CONUS LOW IS STILL EXPECTED TO LINGER OVER SOUTHERN NEW ENGLAND THROUGH THE WEEKEND AND EVENTUALLY MOVE OFFSHORE BY EARLY NEXT WEEK. BOTH THE GFS AND ECMWF HAVE THE LAST BIG BAND OF SHOWERS MOVING EAST AND THEN NORTH FROM THE WESTERN CAROLINAS SATURDAY MORNING. AFTER THAT...MODELS ARE FAIRLY CONSISTENT IN BRINGING THE UPPER LOW SLOWLY EAST ACROSS TN WITH FALLING HEIGHTS AND LIGHTER AMOUNTS OF MOISTURE REMAINING ALONG THE TN/NC BORDER. THE LOW THEN SPINS JUST NORTH OF OUR AREA TO START THE WEEK. PERSISTENT WESTERLY FLOW WILL EVENTUALLY GIVE WAY TO NORTHERLY FLOW AS THE SFC LOW FINALLY MOVES OFFSHORE AND HIGH PRESSURE BEGINS TO REESTABLISH ITSELF. LATEST GFS AND ECMWF AGREE FAIRLY WELL WRT TO THE POSITION AND TRACK OF THE SFC LOW DURING THE LATTER PORTION OF THE MEDIUM RANGE...HOWEVER THE ECMWF IS NOTICEABLY MORE MOIST IN THE 1000-500MB LEVEL. WITH THAT SAID...I KEPT AT LEAST A SLIGHT CHANCE POP OVER THE MAJORITY OF THE FCST AREA THROUGH DAY 6 AND A SOLID CHANCE OVER THE NC MOUNTAINS THROUGH EARLY MONDAY TAPERING TO A SLIGHT CHANCE AFTER THAT. EXPECT TEMPERATURES TO BE A FEW DEGREES BELOW NORMAL WITH A MODEST WARMING TREND ON DAYS 6 AND 7. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... AT KCLT...MODELS IN FAIR AGREEMENT REGARDING LOWERING CIG/VSBY AND ONSET OF PRECIP. EXPECT CIGS TO GRADUALLY LOWER ACROSS THE AREA THROUGH THE PERIOD...WITH LGT S FLOW CONTINUING. CHC OF RAIN THIS MRNG...INCRSNG THIS AFTN WITH MVFR CIG AFT 22Z...IFR AFT 02Z. ELSEWHERE...EXPECT CIGS TO GRADUALLY LOWER ACROSS THE AREA FROM THE W WITH LGT S FLOW CONTINUING. CHC OF RAIN WILL INCREASE THRU THE DAY WITH MVFR CIG MOVG IN FROM THE W BY MID AFTN...IFR AFT 00Z. OUTLOOK...SHOWERS WILL BECOME MORE WIDESPREAD THU. EXPECT A BREAK IN SHOWERS THU NIGHT...THEN MORE SHOWERS AND TSTMS MOVE IN FRI. UNSETTLED WEATHER WILL LINGER THROUGH SAT WITH DRIER CONDITIONS ON SUN. EXPECT MVFR TO IFR CIGS THRU FRI WITH IMPROVING CONDITIONS LATE SAT-SUN. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JPT NEAR TERM...MCAVOY/RB SHORT TERM...JPT LONG TERM...JPT AVIATION...RB WWWW