Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 241440
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
940 AM EST MON NOV 24 2014

.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION FROM THE WEST TONIGHT. A COASTAL
LOW WILL DEVELOP OFF THE SOUTHEAST COAST AND MOVE UP THE ATLANTIC
SEABOARD TOMORROW NIGHT AND WEDNESDAY...BRINGING PRECIPITATION
CHANCES BACK TO THE AREA. DRIER HIGH PRESSURE WILL SPREAD BACK OVER
THE REGION ON THURSDAY AND FRIDAY AND LINGER WELL INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM EST...ABUNDANT LOW LEVEL MOISTURE CONTINUES IN THE
SOUTHWESTERLY FLOW AHEAD OF THE APPROACHING COLD FRONT JUST WEST OF
NASHVILLE TN. THE LOW CLOUDS HAVE LARGELY SCATTERED NEAR THE BLUE
RIDGE SECTIONS OF WRN NC...BUT WILL TAKE SOME TIME TO LIFT AND
SCATTER IN THE DEEPER BOUNDARY LAYER MOISTURE FARTHER S/E. WILL TRIM
MAX TEMPS A DEGREE IN THESE CLOUDIER SE SECTIONS THIS AFTN...BUT
STILL FEATURE PLENTY OF 70S. VERY LIGHT RADAR RETURNS ARE
ENCROACHING ON THE EXTREME SE PIEDMONT THIS MORNING...BUT THE DEEPER
MOISTURE WILL REMAIN CONFINED TO THE COASTAL PLAIN...AND
FORCING/MOISTURE ALONG THE APPROACHING COLD FRONT STILL LOOK QUITE
WEAK. IN ADDITION...INSTABILITY WILL BE LIMITED BY FAIRLY WARM MID
LEVEL TEMPS. AN ISOLD AFTN SHOWER MENTION SHOULD SUFFICE IN THE
LOWER PIEDMONT AND WRN MTNS THROUGH LATE DAY.

OTHERWISE...UPPER HEIGHT FALLS WILL CONTINUE TO SPREAD INTO THE
EASTERN STATES THROUGH TONIGHT...WITH THE ATTENDANT COLD FRONT
GRADUALLY PUSHING ITS WAY ACROSS OUR REGION THIS EVENING. ANY
LINGERING CLOUD COVER SHOULD CLEAR QUICKLY BEHIND THE FRONT...EXCEPT
PERHAPS WITHIN THE SHALLOW MOIST WESTERLY FLOW REGIME ACROSS THE
MTNS OVERNIGHT. MIN TEMPS ARE EXPECTED TO AVERAGE A LITTLE WARMER
THAN CLIMO...AS COLD ADVECTION TAKES ITS TIME TO BECOME ESTABLISHED.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
AS OF 330 AM MON...DRY HIGH PRESSURE WILL PREVAIL OVER THE CWFA MOST
OF TUESDAY WHILE AN EXPANSIVE UPPER TROUGH COVERS THE ERN US. CAA
WILL CONTINUE INTO THE SOUTHEAST WITH COLD FRONT ORIENTED ALONG THE
SOUTH ATLANTIC COAST AND SWWD INTO THE CENTRAL GULF. A SHORTWAVE
ROUNDING THE BASE OF THE LONGER TROUGH WILL ENCOUNTER THE FRONT AND
START TO SPIN UP A SFC LOW OVER FLORIDA BY TUESDAY EVENING AND IT IS
THIS LOW WHICH WILL BRING INCREASING PRECIP CHANCES TUE NIGHT INTO
WED AS IT RIDES UP THE SOUTHEAST COAST. THOUGH THERE ARE STILL
DIFFERENCES OF PERHAPS 50-100 MILES IN THE LOW TRACK BETWEEN THE
GFS/NAM/CMC/EC...THE 00Z CYCLE OF GUIDANCE HAS COME INTO FAIRLY GOOD
AGREEMENT...THOUGH THE NAM REMAINS A SLIGHT OUTLIER IN TAKING THE
LOW MORE OFFSHORE AND NOT DEEPENING IT AS QUICKLY. THERE IS
CONSENSUS ON THE TIMING OF PEAK POPS...A LITTLE BEFORE DAYBREAK WED
IN THE LOWER SC PIEDMONT ZONES...AND LATE MRNG IN THE I-77 CORRIDOR.
WE WILL GO AHEAD AND ADVERTISE CATEGORICAL VALUES IN THESE AREAS
GIVEN THE INCREASING CONSENSUS.

PRE-EXISTING COLD ADVECTION WILL BE ENHANCED AS THE LOW PASSES
WEDNESDAY. IN THE WESTERN PORTION OF THE CWFA PARTIAL THICKNESSES
WILL ALREADY BE MARGINAL FOR WINTRY PTYPES EARLY WED MRNG...BUT WILL
PLUNGE FURTHER BEFORE THE LOW LIFTS AWAY. WITH THE ENTIRE AREA
REMAINING ON THE COOL SIDE OF THE SYSTEM...IT STILL APPEARS THAT
EITHER RAIN OR SNOW WILL RESULT WITH NO ELEVATED WARM LAYERS SEEN ON
ANY OF THE AVAILABLE MODEL GUIDANCE. SFC T OR TW VALUES ONLY FAVOR
SNOW REACHING THE SFC IN THE MOUNTAINS AND HIGHER FOOTHILLS. THERE IS
FAIRLY GOOD CONSISTENCY BETWEEN THE VARIOUS SOURCES OF QPF GUIDANCE
BUT THE BLENDED VALUES ENDED UP CLOSE TO THE GFS ENSEMBLE MEAN.
LIQUID VALUES DO NOT LOOK EXCESSIVE...WELL UNDER AN INCH EVEN IN OUR
SERN/ERN ZONES NEAREST THE LOW. SNOW TOTALS IN THE MTNS LOOK TO BE
ADVISORY-LEVEL ATTM. SUFFICIENTLY COLD AIR IS ONLY QUESTIONABLE EARLY
IN THE EVENT LEAVING LIQUID QPF AS THE MAIN FACTOR IN SNOWFALL.
PROVIDED THAT THE MODELS MAINTAIN THE COASTAL TRACK I HAVE PRETTY
GOOD CONFIDENCE IN THESE TOTALS.

BY WED NIGHT AN ADDITIONAL PUSH OF COLD AIR AND MOISTURE WILL REACH
THE MTNS AS A SHORTWAVE EMBEDDED IN THE TROUGH EXITS THE OHIO
VALLEY. LLVL WINDS WILL VEER TO NWLY ACRS THE AREA BY THU MRNG AND
PROG SOUNDINGS SUGGEST A MINOR SNOWFALL EVENT NEAR THE TENN
BORDER. ADDITIONAL ACCUMS OF LESS THAN AN INCH ARE EXPECTED. FLURRIES
MAY CONTINUE ON THE WINDWARD SLOPES THRU THURSDAY BEFORE MOISTURE
FINALLY DIMINISHES THU NIGHT. DOWNSLOPING WINDS ACRS THE AREA THU
AFTN WILL HELP TEMPS REBOUND INTO THE 50S ACRS THE PIEDMONT.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
AS OF 345 AM MON...CANADIAN HIGH PRESSURE MOVES BACK INTO THE REGION
FRIDAY AND THIS KEEPS THINGS DRY FOR MOST OF THE WEEKEND. THE UPPER
FLOW FLATTENS OUT OVER THE WEEKEND...AND EVEN AS THE SFC HIGH SHIFTS
OFFSHORE SATURDAY IT APPEARS RETURN FLOW DOES NOT BRING BACK MUCH IN
THE WAY OF MOISTURE INTO THE AREA. INSTEAD...BOTH THE 24/00Z GFS AND
EC BRING THE NEXT SHOT AT PRECIP WITH A WEAK COLD FRONT TRAILING A
NORTHERN-STREAM LOW SUNDAY. WE WILL CONTINUE TO FEATURE BELOW NORMAL
ALBEIT MODERATING TEMPS THRU THE MEDIUM RANGE.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
AT KCLT...ABUNDANT LOW LEVEL MOISTURE ON SW FLOW WILL CONTINUE TO
ADVECT TOWARD THE AIRFIELD THROUGH THE DAY. THIS MOISTURE IS MAINLY
AT MVFR LEVELS IN THE MODEL PROFILES...AND A GRADUAL IMPROVEMENT IN
CIG HEIGHT IS EXPECTED BEFORE THE AIRFIELD FINALLY SEES SCT TO BKN
VFR LEVEL CLOUDS TOWARD EVENING AND THEN OVERNIGHT. MIXING ON SW
FLOW WILL PRODUCE GUSTS IN THE 20 TO 25 KT RANGE THROUGH THE DAY. AN
ISOLATED SHOWER CANNOT BE RULED OUT BUT CONFIDENCE IS TOO LOW TO
MENTION IN THE TAF.

AT KAVL AND KHKY...EARLY MORNING MOISTURE HAS SCATTERED OUT...BUT
SCATTERED REDEVELOPMENT OF MVFR/LOWER VFR LEVEL CLOUDS IS LIKELY
WITH HEATING TODAY. EXPECT SWLY GUSTS OF 20 TO 25 KT WITH MIXING
THROUGH THE DAY...THEN WINDS TURNING W TO NW TONIGHT WITH FROPA.
KAVL COULD SEE AN ISOLD SHRA LATE DAY...BUT CHANCES ARE TOO LOW TO
MENTION.

AT THE UPSTATE TAF SITES...ABUNDANT LOW LEVEL MOISTURE IS LEADING TO
WIDESPREAD MVFR CIGS...WITH IFR TO LIFR CIGS/VSBY AT TIMES AT KAND.
CONDITIONS SHOULD IMPROVE WITH MIXING THROUGH LATE MORNING...WITH
MVFR CIGS FINALLY SCATTERING TO VFR THIS AFTN. EXPECT WIND GUSTS OF
20 TO 25 KT ON THE SW FLOW WITH MIXING THROUGH LATE DAY. AN ISOLATED
SHOWER CANNOT BE RULED OUT...BUT CHANCES ARE MUCH TOO LOW TO MENTION
IN THE TAF THROUGH THIS EVENING. FROPA TONIGHT WILL LEAD TO A
GRADUAL VEERING OF THE SFC WINDS TOWARD WESTERLY.

OUTLOOK...BRIEF DRYING FOLLOWS A COLD FRONT TONIGHT THROUGH TUESDAY.
PRECIPITATION MAY RETURN TUE NIGHT INTO WED...WITH A WINTRY MIX
POSSIBLE IN THE MTNS OR NEAR KHKY. ANOTHER ROUND OF SCATTERED
SHOWERS MAY AFFECT THE NRN TIER WED NIGHT INTO THU MORNING. MORE
SETTLED WEATHER WILL THEN RETURN THROUGH THE END OF THE WEEK.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       HIGH  93%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH  97%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  89%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH  91%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH  97%     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...HG/WIMBERLEY
NEAR TERM...HG/JDL
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...HG/JDL


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