Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 241756
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1256 PM EST MON NOV 24 2014

.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TONIGHT. LOW PRESSURE WILL
THEN DEVELOP OFF THE SOUTHEAST COAST AND MOVE UP THE ATLANTIC
SEABOARD TOMORROW NIGHT AND WEDNESDAY...BRINGING PRECIPITATION
CHANCES TO THE AREA. DRIER HIGH PRESSURE IS EXPECTED TO RETURN
THURSDAY AND LINGER INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 1245 PM EST...REGIONAL RADARS SHOW ISOLATED SHOWERS BRUSHING
THE LOWER PIEDMONT FROM SE OF GREENWOOD TO SE OF MONROE. THIS SHOULD
BE THE WESTWARD EXTENT OF ANY ADDITIONAL ACTIVITY THROUGH THE
AFTN...AND ANY SFC BASED INSTABILTY AHEAD OF THE APPROACHING FRONT
SHOULD BE LIMITED TO 100 TO 200 J/KG OR LESS IN THE PIEDMONT THROUGH
LATE DAY GIVEN THE WARM TEMPERATURES ALOFT. THE APPROACHING COLD
FRONT WAS ANALYZED FROM NEAR CROSSVILLE TN TO NW GA EARLY THIS AFTN.
THE MOSTLY DRY BOUNDARY SHOULD MOVE THROUGH THE MOUNTAINS THIS
EVENING AND THEN SLOWLY SETTLE EAST OF THE AREA THROUGH THE EARLY
OVERNIGHT HOURS.

ADDITIONAL H5 HEIGHT FALLS ARE EXPECTED FROM THE SRN PLAINS TO THE
LOWER MS RIVER VALLEY TUESDAY. MID AND UPPER LEVEL MOISTURE WILL
FILL IN OVERHEAD ACROSS OUR REGION IN RESPONSE TO THE SHARPENING
TROUGH TO THE WEST AND SFC LOW PRESSURE DEVELOPING OFF THE FL/GA
COAST TO THE SE. HOWEVER...LOWER LEVELS ACROSS OUR REGION WILL
REMAIN FAIRLY DRY AS THE SFC TO 850 MB WINDS REMAIN A WESTERLY TO NW
DOWNSLOPE. WILL KEEP MAX TEMPS A SHADE ON THE COOLER SIDE OF
GUIDANCE DUE TO THE HIGH CLOUDINESS THROUGH TUESDAY.

&&

.SHORT TERM /TUESDAY NIGHT 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 /18Z MONDAY THROUGH SATURDAY/...
AT KCLT...SEVERAL ROUNDS OF LIGHT RAIN SHOWERS COULD STREAM BY TO
THE SE IN THE DEEP LAYER SWLY FLOW AHEAD OF THE APPROACHING COLD
FRONT...BUT NONE OF THESE SHOWERS SHOULD REACH THE KCLT AIRFIELD.
THE MVFR CIGS HAVE ALREADY STARTED TO LIFT/SCATTER AND ONLY A TEMPO
FOR MVFR WILL BE NEEDED THROUGH 20Z. EXPECT SW GUSTS INTO THE LOWER
20S TO CONTINUE WITH MIXING THROUGH LATE AFTN...WITH WINDS
DECOUPLING SLIGHTLY THIS EVENING AND THEN SHIFTING TO THE WNW WITH
FROPA BY 08Z. MID AND HIGH LEVEL CLOUDS WILL THICKEN UP OVERHEAD
LATE TONIGHT THROUGH TUESDAY AS A TROUGH AXIS SHARPENS UP TO THE
WEST.

ELSEWHERE...NO FURTHER LOW CLOUD RESTRICTIONS ARE EXPECTED...AS
EARLY DAY BOUNDARY LAYER MOISTURE HAS SCATTERED OUT AND ONLY LIMITED
MOISTURE IS EXPECTED WITH THE FRONT THIS EVENING. GUSTS TO 20 KT OR
BETTER WILL CONTINUE UNTIL THE WINDS SHIFT WESTERLY WITH
FROPA...BECOMING NW AT KAVL BY EVENING AND THEN STEADILY W TO NW AT
THE FOOTHILLS OVERNIGHT. MID AND HIGH CLOUDS WILL THICKEN UP
OVERHEAD ACROSS THE REGION LATE TONIGHT THROUGH TUESDAY AS A TROUGH
AXIS SHARPENS UP TO THE WEST.

OUTLOOK...COASTAL LOW PRESSURE WILL DEEPEN AHEAD OF AN APPROACHING
TROUGH FROM THE WEST TUE NIGHT INTO WED. ANOTHER UPPER LEVEL WAVE
WILL CROSS THE REGION WED NIGHT INTO THU. PRECIPITATION AND
ASSOCIATED RESTRICTIONS FROM THESE FEATURES MAY RETURN IN THE FORM
OF A WINTRY MIX FROM KAVL TO KHKY...WITH MAINLY RAIN EXPECTED FROM
KGSP TO KCLT AND POINTS SOUTH. DRIER CONDITIONS WILL RETURN BY LATE
WEEK.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH  91%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH  90%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH  93%     HIGH 100%
KHKY       HIGH  94%     HIGH  93%     HIGH 100%     HIGH 100%
KGMU       HIGH  91%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH  90%     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
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...HG



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