Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 171058
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
658 AM EDT THU APR 17 2014

.SYNOPSIS...
AN UNSEASONABLY COLD AIR MASS WILL REMAIN OVER THE REGION INTO
FRIDAY. A SUBTROPICAL LOW WITH DEEP MOISTURE WILL DEVELOP ACROSS THE
SOUTHEAST STATES ON FRIDAY AND SATURDAY. BY EARLY NEXT
WEEK...TEMPERATURES SHOULD RANGE CLOSE TO NORMAL AHEAD OF AN
APPROACHING COLD FRONT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 645 AM...CIRRUS HAS OVERSPREAD THE AREA AND WILL REMAIN THRU
THE DAY. GUIDANCE IS NOW IN GOOD AGREEMENT SHOWING LOW CLOUDS MOVING
INTO THE AREA FROM THE SOUTH THIS EVENING AND OVERNIGHT. SAT PIX
SHOW THESE CLOUDS ALONG THE GA/SC COAST WITH A NORTHWARD TRAJECTORY.
OTHERWISE...GOING FCST LOOKS ON TRACK...SO UPDATES MAINLY FOR
CURRENT CONDITIONS.

AS OF 245 AM...HIGH PRESSURE REMAINS RIDGED INTO THE AREA FROM THE
NE TODAY. RISING THICKNESSES...SUN FILTERING THRU MOSTLY THIN CIRRUS
AND A MODERATING AIR MASS WILL LEAD TO WARMER HIGHS TODAY.
HOWEVER...THEY WILL STILL BE AROUND 10 DEGREES BELOW NORMAL. NELY
WINDS OUTSIDE OF THE MTNS WILL BECOME GUSTY WITH MIXING ACROSS THE
UPSTATE AND NE GA...AND POSSIBLY PARTS OF NC...BY MID MORNING AS
MIXING BEGINS. GUSTS SHUD TAPER OF FOR THE AFTERNOON. WINDS ACROSS
THE MTNS WILL BE SLY AND COULD SEE GUSTS FOR THE AFTERNOON.

ALTHOUGH SFC WINDS WILL REMAIN NELY OUTSIDE OF THE MTNS TONIGHT WITH
HIGH PRESSURE REMAINING IN PLACE...LOW LEVEL FLOW BECOMES SLY AHEAD
OF AN APPROACHING SHORT WAVE IN THE SWLY UPPER FLOW AND A DEVELOPING
GULF OF MEXICO SFC LOW. GUIDANCE NOW INDICATES LOW LEVEL MOISTURE
WILL MOVE INTO THE AREA FROM THE SOUTH AS THE SHORT WAVE APPROACHES
THE AREA. LOWS SHUD BE QUITE A BIT WARMER THAN PREVIOUS NITES WITH
INCREASING CLOUDS AND MODERATING AIR MASS. LOWS STILL END UP AROUND
5 DEGREES BELOW NORMAL...AND COULD LEAD TO PATCHY FROST ACROSS THE
NC MTNS.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
AS OF 240 AM THURSDAY...THE GFS AND ECMWF INDICATE THAT AN AMPLIFIED
H5 TROUGH WILL RIPPLE OVER THE DEEP SOUTH ON FRIDAY. BOTH SOLUTIONS
SHOW THE TROUGH CLOSING OFF OVER S. GA AND N. FL...WITH THE GFS
NORTH OF THE ECMWF. AT THE SFC...LOW PRESSURE WILL LIKELY ORGANIZE
ALONG THE GA/FL LINE...WITH NEW ENGLAND CENTERED HIGH PRESSURE
RIDGING ACROSS THE WESTERN CAROLINAS. THERE IS STRONG AGREEMENT
WITH PLACEMENT OF DEEP MOISTURE AND LIFT ALONG AND EAST OF THE SFC
AND MID LEVEL LOW. HOWEVER...MODEL AGREEMENT IS LOW ACROSS THE
WESTERN CAROLINAS...WITH THE GFS AND ECMWF TRENDING WETTER ACROSS
THE CWA AND NAM REMAINING DRY. BASED ON MODEL TRENDS...I WILL
HIGHLIGHT THE MTNS...UPPER SAVANNAH RIVER VALLEY...AND EASTERN
PIEDMONT WITH CHC POPS FOR SHRA. IN ADDITION...SKY COVER WILL
LIKELY FAVOR MOSTLY CLOUDY CONDITIONS. A BLEND OF PREFERRED MOS
GUIDANCE SUPPORTS HIGHS ON FRIDAY IN THE UPPER 50S.

FRIDAY NIGHT AND SATURDAY...A BAND OF CLOUD COVER AND DEFORMATION
FORCING MAY LINGER ACROSS THE WESTERN CAROLINAS. THIS BAND WILL
LIKELY SLOWLY DRIFT EASTWARD THROUGH SATURDAY. THE FORECAST WILL
INDICATE MOSTLY CLOUDY CONDITIONS WITH SCHC POPS FRIDAY
NIGHT...DECREASING FROM WEST TO EAST DURING THE DAYLIGHT HOURS ON
SATURDAY. SATURDAY HIGHS ARE VERY CHALLENGING...WITH THE PRESENCE OF
CLOUDS AND SHRA WILL LIKELY IMPACT TEMPS BY 10 TO 15 DEGREES. AT
THIS TIME...I WILL FORECAST HIGHS AROUND 5 DEGREES BELOW NORMAL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 3 AM THURSDAY...SUNDAY AND MONDAY...MEDIUM RANGE MODELS INDICATE
THAT THE MID LEVEL CLOSED LOW WILL DRIFT EAST OVER THE WESTERN
ATLANTIC AS MID LEVEL RIDGING INCREASES EAST OF THE MISSISSIPPI
RIVER VALLEY. THIS PATTERN SHOULD RESULT IN WEAK SFC HIGH PRESSURE
AND DRY AIR TO BUILD WEST TO EAST ACROSS THE FORECAST AREA SUNDAY
AND MONDAY. HIGH TEMPERATURES WILL LIKELY RANGE WITHIN 2 TO 4 DEGREES OF
NORMAL.

ON TUESDAY...THE GFS AND ECMWF INDICATE THAT A MID LEVEL SHORT WAVE
WILL RIPPLE OVER THE FORECAST AREA DURING THE DAYLIGHT HOURS. AT THE
SFC...A WEAK COLD FRONT IS TIMED TO SWEEP ACROSS THE SOUTHERN
APPALACHIAN REGION DURING THE AFTERNOON. BOTH SOLUTIONS INDICATES
THAT A FIELD OF WEAK CAPE WILL EXIST ALONG AND AHEAD OF THE COLD
FRONT. THE APPROACH OF THE MID LEVEL S/W AND COLD FRONT...COMBINED
WITH WEAK INSTABILITY SHOULD YIELD AT LEAST SCT SHRA/TSRA. DRY
CANADIAN HIGH PRESSURE SHOULD BUILD ACROSS THE REGION ON WEDNESDAY.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AT KCLT AND ELSEWHERE...CIRRUS HAS OVERSPREAD THE AREA AND WILL
CONTINUE THRU THE PERIOD. GUIDANCE NOW IN BETTER AGREEMENT ON LOW
VFR CLOUDS MOVING IN FROM THE SOUTH DURING THE EVENING AND BECOMING
BKN OVERNIGHT. MVFR CIGS CANNOT BE RULED OUT BEFORE DAYBREAK...BUT
BULK OF THE GUIDANCE KEEPS THEM LOW VFR. NELY WIND THIS MORNING
BECOMES GUSTY WITH MIXING BY MID-MORNING ACROSS THE UPSTATE...THEN
WEAKENS DURING THE AFTERNOON AS IT TURNS ENE. KAVL THE EXCEPTION
WHERE LIGHT NLY WIND EARLY THIS MORNING BECOMES SLY BEFORE NOON THEN
BECOMES GUSTY FOR AFTERNOON. KAVL WIND RETURNS TO LIGHT NLY DURING
THE EVENING. ELSEHWERE...WINDS TURN BACK TO NELY BUT REMAIN ABOVE
THE LIGHT CATEGORY.

OUTLOOK...CEILING AND VISIBILITY RESTRICTIONS WILL RETURN FRIDAY AND
SATURDAY AS A COLD FRONT APPROACHES FROM THE WEST AND A LOW PRESSURE
SYSTEM DEVELOPS ALONG THE COAST.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-11Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  97%
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...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR GAZ010-017.
     FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR GAZ018-026-028-
     029.
NC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR NCZ035>037-048-
     051>053-056>059-062>065-068>072-082-501>510.
SC...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR SCZ003-006>009-
     011>014-019.
     FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ001-002-004-
     005-010.

&&

$$
SYNOPSIS...NED
NEAR TERM...RWH
SHORT TERM...NED
LONG TERM...NED
AVIATION...RWH






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