000
FXUS62 KGSP 032037
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
337 PM EST MON MAR 3 2014

.SYNOPSIS...
A COLD FRONT WILL MOVE SOUTHEAST OF THE AREA THIS EVENING AND OVERNIGHT.
HIGH PRESSURE WILL THEN BUILD OVER THE REGION FROM THE NORTH AND
EAST ON TUESDAY. A COASTAL LOW WILL DEVELOP TO OUR SOUTH ON THURSDAY
AND TRACK UP THE SOUTHEAST COAST THROUGH FRIDAY. DRIER HIGH PRESSURE
IS THEN EXPECTED TO RETURN IN ITS WAKE FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 225 PM EST MONDAY...A STRONG BACK DOOR COLD FRONT IS DROPPING
QUICKLY SOUTHWARD ACROSS THE FORECAST AREA THIS AFTN. SO FAR THE MID
SHIFT/S HOURLY TEMPERATURES HAVE BEEN VERY GOOD...THOUGH THE COLD
AIR IS STARTING TO MOVE SOUTHWARD A LITTLE MORE QUICKLY. LOW TOPPED
SHOWERS ARE DEVELOPING ALONG AND BEHIND THE FRONTAL BNDRY. MOST OF
THE HEAVIER ACTIVITY IS FAVORING THE NC FOOTHILLS AND IS NOT FALLING
OUT ACROSS THE PIEDMONT IN THE COLDEST AIR. THAT SAID...THERE IS
LIGHTER PCPN...MORE LIKE DRIZZLE...FALLING IN THESE AREAS. THE WAY
IT APPEARS NOW...THE NC PIEDMONT AND FOOTHILLS ARE LIKELY TO SEE A
PERIOD OF LIGHT FREEZING RAIN AND DRIZZLE. IF THE NAM BUFKIT
SOUNDINGS ARE TO BELIEVED...LIGHT FREEZING PCPN COULD FALL FOR 2 TO
4 HOURS. GROUND TEMPERATURES ARE WARM AND THE PUBLIC IMPACT STILL
APPEARS TO BE MINIMAL. COORIDNATED WITH THE BLACKSBURG AND COLUMBIA
FORECAST OFFICES AND THEY ARE NOT PLANNING TO ISSUE ADVISORIES
EITHER. DEPENDING ON HOW STRONG THE LLVL ASCENT IS BEHIND THE
FRONT...AND AS WE GET INTO A LITTLE BETTER DEEP LAYER FORCING AS THE
WEAKING UPPER LOW MOVES INTO THE MOUNTAINS...THERE IS STILL A CHANCE
A FREEZING RAIN/DRIZZLE ADVISORY MIGHT BE NEEDED FOR PARTS OF THE NC
ZONES.

DRIER AIR WILL MOVE IN LATER TONIGHT...THOUGH LOW CLOUDS MAY NOT
EVER CLEAR OUT OF THE UPSTATE AND NE GA BEFORE RETURN FLOW
DEVELOPS. I/VE GONE WITH HIGHER CLOUD COVER OVER THE SRN ZONES TO
ACCOUNT FOR THIS. IT WILL BE QUITE COLD OVERNIGHT AS THE ARCTIC
AIRMASS MOVES IN. LOWS OVER THE WRN NC PIEDMONT ARE EXPECTED TO FALL
TO AROUND 20 WITH BREEZY CONDITIONS...MAKING FOR A COLD NIGHT.
PATCHES OF BLACK ICE ARE ALSO A GOOD BET AS TEMPERATURES FALL TO
BELOW FREEZING. HOPEFULLY THE WINDY CONDITIONS WILL LIMIT THE
COVERAGE OF BLACK ICE...BUT IT/S WORTH A MENTION IN A SPECIAL
WEATHER STATEMENT. AS FOR THE WINDS...GUSTS UP TO 30-35 MPH ARE
EXPECTED THROUGH THE LATE EVENING HOURS OVER THE UPSTATE AND SRN NC
PIEDMONT.

COLD CONDITIONS PERSIST ON FRIDAY WITH SRATO-CU HOLDING ON OVER THE
SOUTH AND HIGH CLOUDS INCREASING EVERYWHERE ELSE.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
AT 230 PM EST MONDAY...A RATHER COMPLEX WEATHER PATTERN IS IN STORE
FOR THE SHORT TERM AS A COUPLE SOUTHERN STREAM WAVES AFFECT THE
REGION. THE FORECAST WILL INDICATE THAT FOR THE MOST PART...TUE AND
WED SHOULD BE UNEVENTFUL. HOWEVER...A FAST MOVING SOUTHERN STREAM
WAVE WILL MOVE ACROSS THE DEEP SOUTH TUE NIGHT INTO WED WHICH WILL
ACTIVATE THE STALLED FRONTAL BOUNDARY TO THE SW. A WEAK WAVE OF LOW
PRESSURE WILL DEVELOP AND MOVE EAST ACROSS GA/SC AND THEN OFF THE
COAST ON WED. THERE IS VARYING QPF RESPONSE FROM THE MODELS WITH THE
GFS/CMC THE MOST AGGRESSIVE WITH THE BRINGING MEASURABLE PRECIP INTO
UPSTATE SC...WHILE THE NAM KEEPS THE PRECIP WELL TO THE SOUTH. THE
12Z ECM IS IN BETWEEN AND BRINGS MEASUABLE PRECIP INTO OUR SOUTHERN
PERIPHERY. WILL LEAN TOWARD THE ECM WHICH WOULD BRING MAYBE A COUPLE
HUNDRETHS OF MEASURABLE PRECIP INTO THE SOUTHERN UPSTATE. THE
COMPLICATION IS THAT TEMPS WILL BE NEAR OR JUST BELOW FREEZING EARLY
WED...SO SOME LIGHT FREEZING RAIN IS POSSIBLE. ONCE THE WAVE
PASSES...WED SHOULD BE UNEVENTFUL WITH MAX TEMPS REACHING WELL INTO
THE 50S MOST AREAS..EXCEPT THE HIGHER ELEVATIONS IN NC.

ALL EYES THEN TURN TO THE NEXT MORE SIGNIFICANT SOUTHERN STREAM WAVE
THAT WILL AFFECT THE REGION THU INTO EARLY FRI. THE MODELS ARE IN
DECENT AGREEMENT ON TIMING...BUT DIFFER SOMEWHAT ON STRENGHTH. THE
CMC IS THE STRONGEST WITH THIS FEATURE AND HAS THE MOST QPF
RESPONSE. THE 12Z NAM IS AN OUTLIER AND NOT USED. ALL THE GLOBAL
MODELS AGREE THAT THE WAVE WILL CAUSE SURFACE CYCLOGENESIS IN THE
NORTHERN GOM WITH THE LOW THEN MOVING EAST ACROSS N.FLORIDA ON THU
AND THEN NE TO OFF THE CAROLINA COAST THU NIGHT. THE FORECAST WILL
SHOW PRECIP DEVELOPING RAPIDLY LATE WED NIGHT AND SPREADING ACROSS
THE AREA ON THU. THE PRECIP WILL THEN PULL EASTWARD THU NIGHT AND
END OVER MOST OF THE AREA EXCEPT PERHAPS THE I-77 CORRIDOR BY 12Z
FRI. STRONG COLD AIR DAMMING WILL COMMENCE ON THU AS PRECIP
OVERSPREADS THE AREA. HOWEVER...MODEL BLEND PARTIAL THICKNESSES...
FORECAST SURFACE TEMPS ALL FAVOR MAINLY RAIN. THE EXCEPTION...
WILL BE ON THU ALONG THE BLUE RIDGE AND NORTHERN NC PIEDMONT WHERE
IF PRECIP BEGINS SOON ENOUGH A MIXTURE OF FREEZING RAIN/SLEET MAY
OCCUR. HOWEVER...AS THE MOST SIGNIFICANT QPF ARRIVES ALL RAIN IS
SUPPORTED. AS THE PRECIP PULLS OUT THU NIGHT...ENOUGH COLD AIR
ARRIVES TO CHANGE RAIN TO SNOW IN THE NORTHERN MOUNTAUINS AND
PERHAPS ANOTHER PERIOD OF FREEZING RAIN ELSEWHERE ACROSS THE
MOUNTAINS. THE WX GRIDS WERE GENERATED USING THE TOP DOWN METHOD.
USED CONSENSUS APPROACH FOR TEMPS TUE NIGHT AND WED...BUT THEN USED
A BLEND OF THE RAW GFS/ECM FOR TEMPS WED NIGHT AND THU TO CAPTURE
THE DEVELOPING CAD/WEDGE. TOTAL ICE ACCUMULATION AT THIS TIME IS JUST
A FEW HUNDRETHS ACROSS THE BLUE RIDGE AND NORTHERN NC PIEDMONT. SNOW
IN THE NORTHERN MOUNTAIONS IS CURRENTLY FORECAST TO BE LESS THAN 1
INCH.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF MIDDAY MONDAY...SHORTWAVE TROF WILL MOVE OFF THE SOUTHEAST
COAST FRIDAY WITH TRANSIENT HIGH PRESSURE THEN CROSSING THE REGION
FRIDAY NIGHT INTO SATURDAY. THE 12Z EC DEVELOPS CYCLOGENESIS A BIT
CLOSER TO SHORE THAN PREVIOUS RUNS...MUCH CLOSER THAN THE GFS...AND
DEVELOPS DEFORMATION ZONE PRECIP OVER CENTRAL NC /MOSTLY EAST OF OUR
FA/. THIS IS NOT BACKED UP BY THE CMC OR GFS ENSEMBLE...AND ALSO NOTE
THAT THE 00Z EC AND 12Z GFS WERE IN AGREEMENT ABOUT A LARGELY DRY
FCST FRIDAY. LOW POPS FRIDAY MORNING WILL COVER THE POSSIBILITIES...
BUT POPS SHOULD TREND DOWN BEGINNING THEN ANYWAY.

RETURN FLOW FROM THE GULF AND REBOUNDING PARTIAL THICKNESSES SUPPORT
NEAR NORMAL TEMPS RETURNING FRIDAY. WILL CAUTIOUSLY AVOID WARMEST
GUIDANCE SINCE WE WILL BE COMING OUT OF A WEDGE EVENT...THOUGH PARENT
HIGH GETS PUSHED WELL OFFSHORE. TEMPS FAIRLY CONFIDENTLY CAN BE
EXPECTED TO RISE SEVERAL DEGREES ABOVE NORMAL FOR SATURDAY IN SW FLOW
AND AT LEAST PARTIAL SUNSHINE.

ANOTHER CLIPPER SHORTWAVE WILL DIVE THRU THE GREAT LAKES SATURDAY
NIGHT...REACHING NEW ENGLAND BY SUN AFTN. SFC CYCLONE THUS SHOWN TO
DEVELOP DURING THIS TIMEFRAME OVER THE CENTRAL APPALACHIANS AS NEXT
FRONT PUSHES THRU THE OHIO VALLEY. SOME EARLIER GUIDANCE PHASED THIS
TROF WITH ONE FORMING IN THE LEE OF THE SRN ROCKIES...SWIFTLY
BRINGING THE FRONT THRU OUR CWFA SUNDAY POTENTIALLY PRECEDED BY
SEVERE WX. LATEST GUIDANCE CYCLE IS WEAKER AND DRIER WITH THE
FRONT...SHOWING IT LOSING A LOT OF STEAM AS IT CROSSES THE SRN
APPALACHIANS. SEVERE WX THREAT IN THE CONSENSUS SCENARIO IS MINIMAL
WITH 850MB WINDS WEAKER AND MORE VEERED...AND BASICALLY NO
INSTABILITY SHOWN AHEAD OF THE MORNING FROPA. TEMPS REMAIN WARM
ENOUGH AND QPF SMALL ENOUGH THAT PTYPE CONCERNS ARE ALSO
MINIMAL...WITH PARTIAL THICKNESSES INDICATING A BRIEF MIX POSSIBLE IN
THE MTNS AROUND DAYBREAK SUNDAY. TEMPS REMAIN SLIGHTLY ABOVE NORMAL
SUN-MON.

&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/...
AT KCLT...THE COLD FRONT HAS MOVED THROUGH THE AIRFIELD AND WINDS
WILL BE OUT OF THE NORTHEAST THROUGH THE VALID PERIOD OF THE TAF.
WINDS WILL GUST UP TO 26-28 KTS THROUGH LATE EVENING. EXPECTING IFR
CIGS FOR 3 TO 4 HOURS BEFORE RISING INTO THE MVFR RANGE AS DRIER
LLVL AIR MOVES IN FROM THE NORTH. LIGHT RAIN AND DRIZZLE WILL
PERSIST FOR SEVERAL MORE HOURS. IT STILL APPEARS THAT A PERIOD OF
FREEZING RAIN/DRIZZLE AND EVEN A FEW ICE PELLETS IS POSSIBLE BETWEEN
21-01 UTC THIS EVENING. IN FACT...THIS IS WELL SUPPORTED BY MUCH OF
THE MODEL GUIDANCE. ICE ACCUMULATIONS WILL BE LIGHT...BUT A GLAZE ON
ELEVATED SFC/S IS POSSIBLE.

ELSEWHERE...A STRONG BACK-DOOR COLD FRONT WILL CROSS THE UPSTATE TAF
SITES OVER THE NEXT COUPLE HOURS...RESULTING IN GUSTY NE WINDS.
WINDS OVER THE UPSTATE WILL GUST UP TO 24 TO 26 KTS AND AT KAVL
WINDS WILL GUST AS HIGH AS 30 KTS BY LATE AFTN. AREAS OF DRIZZLE
WILL LOWER VSBYS...ESPECIALLY OVER THE UPSTATE. DRIER AIR WILL
GRADUALLY RAISE CIGS INTO THE MVFR RANGE BY LATE AFTN WITH VFR
CONDITIONS EXPECTED OVERNIGHT.

OUTLOOK...DRY HIGH PRESSURE RETURNS TUESDAY AND WEDNESDAY WITH VFR
CONDITIONS. FLIGHT RESTRICTIONS AND PRECIP MAY RETURN TO THE AREA
THURSDAY AHEAD OF A GULF LOW PRESSURE SYSTEM.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-20Z
KCLT       HIGH  85%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH  81%     HIGH  80%     HIGH 100%     HIGH 100%
KAVL       HIGH  83%     HIGH  80%     MED   72%     HIGH 100%
KHKY       MED   77%     HIGH  96%     HIGH 100%     HIGH 100%
KGMU       MED   77%     HIGH  95%     HIGH 100%     HIGH 100%
KAND       MED   73%     HIGH  89%     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...JPT
NEAR TERM...MCAVOY
SHORT TERM...LG
LONG TERM...WIMBERLEY
AVIATION...MCAVOY