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000
FXUS62 KGSP 161045
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
645 AM EDT WED APR 16 2014

.SYNOPSIS...
AN UNSEASONABLY COLD AIR MASS WILL REMAIN OVER THE REGION INTO
FRIDAY. A DEEP UPPER TROUGH ARRIVES FROM THE WEST TO START THE
WEEKEND. BY EARLY NEXT WEEK...TEMPERATURES SHOULD RANGE CLOSE TO
NORMAL AHEAD OF AN APPROACHING COLD FRONT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 645 AM...SKIES ARE CLEAR WITH GENERALLY LIGHT WINDS...EXCEPT
GUSTY ACROSS THE MTNS. TEMPS HAVE FINALLY FALLEN TO OR NEAR FREEZING
ACROSS MOST OF THE AREA. FREEZE WARNING WILL REMAIN IN PLACE THRU
EXPIRATION. OTHERWISE...GOING FCST STILL ON TRACK...SO UPDATES
MAINLY FOR CURRENT CONDITIONS.

AS OF 310 AM TUESDAY...CLOUDS CONTINUE TO DISSIPATE ACROSS THE NC
MTNS AND SHOULD BE GONE BY DAYBREAK. MANY LOCATIONS IN THE FREEZE
WARNING HAVE ALREADY REACHED FREEZING...WITH OTHER LOCATIONS COOLING
BASICALLY ON SCHEDULE. CURRENT FREEZE WARNING WILL REMAIN IN PLACE
THRU EXPIRATION. WINDS HAVE DIMINISHED GREATLY OUTSIDE OF THE MTNS
BUT REMAIN GUSTY...WITH OCCASIONAL STRONG BURSTS ACROSS THE MTNS.
EXPECT THE MTN WINDS TO DIMINISH BY DAYBREAK AS WELL...BUT SHUD
REMAIN GUSTY THRU MORNING. EXPECT NELY WINDS OUTSIDE OF THE MTNS TO
BECOME GUSTY WITH MIXING BY MID-MORNING...THEN SLOWLY DIMINISH THRU
THE DAY. MTN WINDS WILL DIMINISH AND TURN SELY FOR THE AFTERNOON.
SUNNY SKIES EXPECTED THRU THE DAY...BUT THE COLD AIR MASS IN PLACE
WILL KEEP HIGHS AROUND 15 DEGREES BELOW NORMAL.

HIGH PRESSURE REMAINS WEDGED INTO THE AREA FROM THE NE TONIGHT. THIS
KEEPS THE COLD AIR MASS IN PLACE ACROSS THE AREA...BUT WITH SOME
MODERATION. THE PRESSURE GRADIENT TIGHTENS TOWARD MORNING AS A SHORT
WAVE MOVING THRU THE SWLY FLOW ALOFT HELPS SPIN UP A WEAK SFC LOW
ALONG THE STALLED COLD FRONT OFF SHORE. ELY FLOW AROUND THIS SYSTEM
COULD BRING LOW LEVEL MOISTURE...AND CLOUDS...INTO THE ERN CWFA
TOWARD DAYBREAK. IF THIS DOES DEVELOP...IT COULD PUT A DAMPER ON
GOOD RADIATIONAL CONDITIONS ACROSS AT LEAST A PORTION OF THE AREA.
THAT SAID...EVEN THE NAM WHICH IS MOST AGGRESSIVE WITH THE FLOW AND
MOISTURE...SHOWS LITTLE TO NO INCREASE IN CONDENSATION PRESSURE
DEFICITS ON THE LOW LEVEL ISENTROPIC SURFACES OVER THE AREA BY
MORNING. GIVEN THE GUIDANCE DISAGREEMENT...WILL KEEP MOSTLY CLEAR
SKIES TONIGHT...BUT SOME WIND CONTINUING. ALL THIS TO SAY FCST LOWS
STILL FALL TO FREEZING ACROSS THE WATCH AREA. THEREFORE...WILL
UPGRADE TO A WARNING FOR TONIGHT. THERE COULD EVEN BE PATCHY
FREEZING TEMPS OUTSIDE OF THE WATCH AREA IN NORMALLY COLDER
LOCATIONS. HOWEVER...THEY SHOULD REMAIN ISOLATED ENUF TO PRECLUDE A
WARNING. FROST IS A LITTLE MORE MARGINAL GIVEN THE RELATIVELY DRY
AIR MASS...WINDS AND POTENTIAL CLOUDS. STILL...HAVE WIDESPREAD AREA
WITH TEMPS REACHING WELL INTO THE FROST PRODUCING CATEGORY. SINCE
ISOLATED FREEZING TEMPS ARE POSSIBLE...WILL GO WITH A FROST ADV FOR
THE REST OF THE UPSTATE AND NE GA.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
AS OF 250 AM WEDNESDAY...ON THURSDAY...BOTH THE GFS AND THE ECMWF
INDICATE THAT A 1045 MB HIGH WILL REMAIN CENTERED NEAR NOVA
SCOTIA...RIDGING SW ACROSS THE EAST COAST. THIS PATTERN WILL PROVIDE
DRY AND COOL LLVL NE FLOW ACROSS THE WESTERN CAROLINAS AND NE GA.
SUNNY TO MOSTLY SUNNY CONDITIONS SHOULD RESULT IN 25 TO 30 DEGREE
WARMING OVER MORNING LOWS. A BLEND OF PREFERRED MOS SUPPORTS HIGH
TEMPERATURES GENERALLY IN THE LOW 60S. THURSDAY NIGHT...H5 TROF AXIS
IS EXPECTED TO RIPPLE OVER THE SOUTHERN MISSISSIPPI RIVER VALLEY. AS
THE TROF APPROACHES...SFC LOW PRESSURE WILL LIKELY DEVELOP OVER THE
NRN GULF OF MEXICO ALONG AN OLD COLD FRONT. AS THE LOW
DEVELOPS...DEEP MOISTURE WILL ADVECT NORTHWARD ACROSS THE DEEP
SOUTH...REACHING THE SOUTHERN APPALACHIAN REGION AROUND SUNRISE.
FORECAST SOUNDINGS INDICATE THAT THE COMBINATION OF HIGH CLOUDS AND
THICKENING MID CLOUDS SHOULD RESULT IN MOSTLY CLOUDY CONDITIONS BY
MID MORNING FRIDAY. AHEAD OF THE SFC LOW...H85 WINDS WILL VEER SOUTH
AND SHOULD PROVIDE WEAK WAA. HIGH TEMPERATURES WILL LIKELY WARM OVER
THURSDAY/S VALUES BY 1-3 DEGREES. SPRINKLES ARE POSSIBLE ACROSS THE
EASTERN PIEDMONT LATE FRIDAY AFTERNOON...BUT THE FORECAST WILL
FEATURE NO MENTIONABLE POPS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 310 PM WEDNESDAY...ON SATURDAY...BOTH THE ECMWF AND GFS INDICATE
THAT LOW PRESSURE WILL DEEPEN ACROSS THE UPPER FL PENINSULA DURING
THE MORNING...TRACKING EAST. AT THE MID LEVELS...A DEEP TROF TO
CLOSED LOW IS EXPECTED TO REMAIN OVER THE SFC LOW...FOLLOWED BY
RIDGING CENTERED OVER THE SOUTHERN MISSISSIPPI RIVER VALLEY. BOTH
SOLUTIONS INDICATE LITTLE TO NO QPF ACROSS THE CWFA. HIGH
TEMPERATURES ARE FORECAST TO RANGE VERY CLOSE TO CLIMO. BROAD HIGH
PRESSURE AND LOW AMPLITUDE RIDGING SHOULD PROVIDE DRY CONDITIONS
WITH NEAR NORMAL TEMPERATURES OVER THE REGION ON SUNDAY. EARLY NEXT
WEEK...ANOTHER MID LEVEL S/W IS EXPECTED TO RIPPLE FROM THE MIDDLE
CONUS ON MON TO THE SOUTHERN APPALACHIANS BY TUESDAY. THE SFC LOW
WILL TRACK NORTH OF THE FORECAST AREA...WITH THE ASSOCIATED COLD
FRONT SWEEPING INTO THE REGION ON TUESDAY. DEEP MOISTURE AND WEAK
INSTABILITY SHOULD SUPPORT SCT SHRA...WITH A FEW TSRA OVER THE UPPER
SAVANNAH RIVER VALLEY AND UPSTATE DURING THE DAYLIGHT HOURS ON
TUESDAY. HIGH TEMPERATURES MAY REMAIN SLIGHTLY ABOVE NORMAL.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...LIGHT NE WIND WILL INCREASE AND BECOME GUSTY
WITH MIXING BY MID MORNING. GUSTS DROP OFF AS WINDS TURN ENE FOR THE
AFTERNOON. KAVL THE EXCEPTION WHERE GUSTY NLY WIND BECOMES SELY FOR
THE AFTERNOON. WINDS RETURN TO NELY OVERNIGHT...BUT REMAIN NEAR 10
KTS THRU THE PERIOD. KAVL WILL SEE A RETURN TO NLY WINDS. THE NAM
SUGGESTS MVFR CLOUDS MAY MAKE A RUN AT KCLT JUST BEFORE DAYBREAK...
WITH OTHER GUIDANCE SHOWING ANY CLOUDS REMAIN SOUTH OF THE AREA
UNTIL SHORTLY AFTER DAYBREAK. WILL KEEP FCST VFR BUT INCLUDE SCT250
FOR NOW.

OUTLOOK...LOW CLOUDS MAY MOVE ACROSS KCLT AND THE SC SITES AFTER
DAYBREAK THURSDAY...THEN LIFT TO VFR THRU THE DAY. OTHERWISE...VFR
EXPECTED THURSDAY. 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...

            10-16Z        16-22Z        22-04Z        04-10Z
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

&&

.CLIMATE...
RECORD LOWS FOR WEDNESDAY APRIL 16...

AVL...26 IN 1943
CLT...29 IN 2008
GSP...24 IN 1907

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...FREEZE WARNING UNTIL 10 AM EDT THIS MORNING FOR GAZ010-017-018-
     026-028-029.
     FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT THURSDAY FOR
     GAZ010.
     FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT THURSDAY FOR
     GAZ017-018-026-028-029.
NC...FREEZE WARNING UNTIL 10 AM EDT THIS MORNING FOR NCZ035>037-048-
     051>053-056>059-062>065-068>072-082-501>510.
     FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT THURSDAY FOR
     NCZ035>037-048-051>053-056>059-062>065-068>072-082-
     501>510.
SC...FREEZE WARNING UNTIL 10 AM EDT THIS MORNING FOR SCZ001>014-019.
     FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT THURSDAY FOR
     SCZ008-009-014.
     FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT THURSDAY FOR
     SCZ001>007-010>013-019.

&&

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