Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 282003 CCA AFDGSP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 251 PM EST FRI NOV 28 2014 .SYNOPSIS... CANADIAN HIGH PRESSURE WILL REMAIN ACROSS THE REGION THROUGH MONDAY AND GRADUALLY WARM EACH DAY. A COLD FRONT WILL THEN PUSH ACROSS THE FORECAST AREA FROM THE NORTH EARLY TUESDAY. && .NEAR TERM /THROUGH SATURDAY/... AS OF 150 PM...MTN WAVE CIRRUS NOT QUITE AS EXTENSIVE AS EXPECTED... BUT SOME CIRRUS WILL LINGER THRU THE REST OF THE AFTERNOON. THE CIRRUS SHUD INCREASE OVERNIGHT AS UPPER LEVEL MOISTURE INCREASES AND A WEAK SHORT WAVE AND UPPER JET MAX MOVES THRU IN THE DEVELOPING ZONAL FLOW. AT THE SFC...HIGH PRESSURE MOVES SLOWLY OFF SHORE THRU THE PERIOD...BRINGING CALM OR LIGHT AND VARIABLE WINDS TONIGHT THEN INCREASING SWLY WINDS SAT. LOWS TONIGHT SHUD BE 5 TO 10 DEGREES BELOW NORMAL...TEMPERED BY THE INCREASE IN CIRRUS AND RISING LOW LEVEL THICKNESSES. HIGHS WILL BE NEAR NORMAL ACROSS THE MTNS SAT AND AROUND 5 DEGREES BELOW NORMAL ELSEWHERE AS THICKNESSES CONTINUE TO RISE...FASTER ACROSS THE MTNS THAN THE PIEDMONT. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... AS OF 200 PM EST FRIDAY...THE SHORT TERM PERIOD INITIALIZES SATURDAY EVENING AMIDST DEAMPLIFIED UPPER FLOW WITH SURFACE HIGH PRESSURE PREVAILING ACROSS THE SOUTHEAST. FURTHERMORE...SURFACE LOW PRESSURE EJECTING OVER THE GREAT LAKES WILL MAKE WAY FOR CANADIAN HIGH PRESSURE DIVING THROUGH THE NORTHERN ROCKIES. WARM ADVECTION AHEAD OF WEAK COLD FRONTAL BOUNDARY ASSOCIATED WITH DEPARTING NORTHERN LOW WILL CONTINUE ACROSS THE DEEP SOUTH THROUGH THE REMAINDER OF THE PERIOD. MOIST UPGLIDE REGIME ACROSS THE MIDSOUTH WILL PREVAIL THROUGH SUNDAY AND INTO MONDAY WITH THE PRIMARY MOISTURE AXIS SLOWLY ADVECTING EASTWARD WITH TIME. BY MONDAY MORNING GUIDANCE FAVORS COLD ADVECTION RAMPING UP ACROSS THE MIDWEST INTO THE OHIO VALLEY ASSOCIATED WITH A REINFORCING COLD FRONT. ISENTROPIC ASCENT REGION WILL SHIFT EAST AHEAD OF THE FRONT LEADING TO IMPROVED UPGLIDE ACROSS THE SOUTHWEST NC AND NORTHEAST GA MOUNTAINS BY EARLY MONDAY MORNING. MODELS FAVOR INCREASING COVERAGE ALONG THE MOUNTAINS THROUGH THE DAY AS THE COLD FRONT APPROACHES FROM THE NORTHWEST EVENTUALLY SLIDING THROUGH THE CUMBERLAND PLATEAU BY PERIODS END. THUS...THE FORECAST WILL REMAIN DRY THROUGH SUNDAY WITH SLIGHT CHANCE POPS BEING INTRODUCED ACROSS THE SOUTHWEST NC AND NORTHEAST GA MOUNTAINS MONDAY MORNING. POPS SPREAD OUT ACROSS THE ENTIRETY OF THE NC/GA MOUNTAINS THROUGH THE DAY WITH CHANCE LEVEL POPS FEATURED BY MONDAY EVENING. TEMPERATURES WILL CONTINUE TO MODERATE THROUGH THE PERIOD WITH HIGHS TOPPING OUT NEARLY 5-10 DEGREES ABOVE NORMAL FOR MOST LOCATIONS ON MONDAY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 230 PM EST FRIDAY...LATEST GLOBAL MODELS CONTINUE TO INDICATE THAT A BACK DOOR COLD FRONT WILL SLIP THROUGH THE FORECAST AREA THROUGH MON NIGHT WITH A CAD SETTING UP BY TUE AS 1043+MB CANADIAN HIGH PRESSURE OVER THE OHIO VALLEY SLIDES INTO NEW ENGLAND. BOTH THE 12Z GFS AND ECMWF TRENDED A BIT WETTER...ESPECIALLY OVER THE NC ZONES ON TUE...IN LIGHT OF UPPER WAVE EMBEDDED WITH A SERIES OF STRONGER UPPER DISTURBANCES MOVING THROUGH OVER MOIST ISENTROPIC UPGLIDE REGIME. THEREFORE...HAVE RAISED POPS INTO THE SOLID CHANCE RANGE OVER THE NORTHERN HALF OF THE CWA ON TUE. THERMAL PROFILE PER 12Z GFS IS SUPPORTIVE OF FREEZING RAIN ON MON NIGHT INTO TUE MORNING...MAINLY AREAS NORTH OF I-40. HOWEVER...THE NEW 12Z ECMWF KEEPS COLDER AIRMASS WELL NORTH OF THE CWA...SUGGESTING ALL LIQUID PRECIP. THEREFORE...HAVE NOT MENTIONED ANY FROZEN PRECIP AT THIS TIME. CONDITIONS SHOULD DRY OUT BY LATE WED...AS WEAK UPPER RIDGING BUILD IN FROM THE WEST AND THE CAD ERODES IN RESPONSE TO AN APPROACHING COLD FRONT FROM THE NW. THE GFS SUGGEST THE FROPA WILL OCCUR ON FRI WHILE THE ECMWF IS AROUND 24HRS LATE...OCCURRING ON SAT. GIVEN THE UNCERTAINTY...HAVE MENTIONED SLIGHT CHANCE POPS OVER THE PEDIMENT WITH LOW END CHANCE POPS OVER THE MTNS ZONES ON FRI...RAMPING DOWN TOWARD FRI NIGHT. TEMPS ON TUE SHOULD REMAIN AROUND 10-15 DEGREES BELOW NORMAL...WITH NEAR NORMAL WED THRU FRI. && .AVIATION /20Z FRIDAY THROUGH WEDNESDAY/... AT KCLT AND ELSEWHERE...THE CENTER OF HIGH PRESSURE HAS MOVED EAST OF THE AREA BRINGING THE LIGHT WINDS TO A SWLY DIRECTION...EXCEPT AT KAVL WHERE WINDS REMAIN NLY. THESE WINDS WILL CONTINUE INTO EARLY EVENING WHEN CALM WINDS ARE EXPECTED. S TO SW WINDS PICK BACK UP AGAIN SAT MORN...BUT SPEEDS WILL BE A LITTLE HIGHER. MTN WAVE CIRRUS THIS AFTERNOON WILL SCATTER OUT OVERNIGHT...BUT RETURN SAT AS HIGH LEVEL MOISTURE RETURNS ALONG WITH AN UPPER JET STREAK. NO VSBY RESTRICTIONS EXPECTED THRU THE PERIOD. OUTLOOK...LOW CLOUDS ARE POSSIBLE SUNDAY MORNING IN THE MOIST SLY FLOW AHEAD OF A COLD FRONT. THE FRONT WILL SLOWLY SLIP SOUTH ACROSS THE SOUTHERN APPALACHIANS ON MONDAY. ON TUESDAY...A STRONG RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE REGION WITH INCREASING LOW LEVEL MOISTURE...LIKELY RESULTING IN WIDESPREAD CEILING RESTRICTIONS THROUGH MID WEEK. CONFIDENCE TABLE... 20-02Z 02-08Z 08-14Z 14-18Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAVL HIGH 100% HIGH 100% HIGH 100% HIGH 100% KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...SBK NEAR TERM...RWH SHORT TERM...CDG LONG TERM...JOH AVIATION...RWH

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