Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 161432
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1032 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 1020 AM...FREEZE WARNING FOR THIS MORNING WAS ALLOWED TO
EXPIRE ON TIME. ALL OF THE AIRPORT OBS HAD RISEN ABOVE FREEZING BY
945 AM...AND MOST SITES IN THE MTNS WERE VERY CLOSE TO FREEZING. IN
THE SUNSHINE THE DANGER TO SFC VEGETATION WAS MINIMAL.

SPOTTY OBS ATTM SHOW BRISK GUSTS WHICH ARE STILL EXPECTED TO
CONTINUE THRU MRNG MIXING BEFORE DIMINISHING. THERE REMAINS SOME
QUESTION AS TO HOW MUCH CLOUD COVER WILL DEVELOP OVER THE COASTAL
PLAIN AND MOVE INLAND. 12Z NAM FEATURES LESS CLOUD COVER THAN 06Z
RUN AND LAMP GUIDANCE HAS NOT PICKED UP ON ANY CLOUDS. SO FOR THE
TIME BEING IT APPEARS THE FROST/FREEZE HEADLINES FOR TONIGHT WILL
STAND AS-ARE.

TEMPS/DEWPTS WERE UPDATED THIS MORNING BUT OTHERWISE APPEAR TO BE ON
TRACK.

PREVIOUS DISCUSSION...AS OF 310 AM TUESDAY...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 /15Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...LIGHT NE WIND WILL INCREASE AND BECOME GUSTY
WITH MIXING THRU MIDDAY. 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...

            14-20Z        20-02Z        02-08Z        08-14Z
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

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...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 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 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/WIMBERLEY
SHORT TERM...NED
LONG TERM...NED
AVIATION...RWH/WIMBERLEY





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