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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
134 AM EDT WED JUL 30 2014

.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL DOMINATE THE SURFACE PATTERN THROUGH 
MIDWEEK...LEADING TO WELL BELOW NORMAL TEMPERATURES MORE TYPICAL OF 
LATE SUMMER OR EARLY AUTUMN. AS THE SURFACE HIGH WEAKENS...MOISTURE 
WILL RETURN FOR THE WEEKEND INCREASING THE CHANCES OF WIDESPREAD 
SHOWERS AND THUNDERSTORMS.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 130 AM EDT WEDNESDAY...CURRENT CONDITIONS REMAIN RATHER 
PLEASANT AS DEWPOINTS HAVE FALLEN INTO THE 50S AT MOST LOCATIONS AND 
EVEN SOME 40S ALONG THE HIGH TERRAIN.  TEMPERATURES HAVE BEEN A 
LITTLE SLOW TO COOL DUE TO PERSISTENT LOW CLOUDS LEFT OVER FROM 
AFTERNOON/EVENING.  AS SKY COVER CONTINUES TO ERODE FOR THE MOST 
PART...TEMPERATURES SHOULD START TO FALL OFF AS RADIATIONAL COOLING 
EFFECTS TAKE HOLD.  BLENDED IN LATEST MAV/MET FOR OVERNIGHT LOWS 
WHICH YIELDED SLIGHTLY LOWER TEMPERATURES ACROSS PORTIONS OF THE 
MOUNTAINS...TO INCLUDE ASHEVILLE WITH A LOW TEMPERATURE OF 53 
DEGREES WHICH IS ONE DEGREE BELOW THE ALL TIME RECORD LOW.  
OTHERWISE...NO SIGNIFICANT CHANGES NEEDED/MADE THEREFORE FORECAST 
REMAINS AS IS.  

PREVIOUS DISCUSSION...

AS OF 200 PM TUE...THE AFTERNOON FORECAST STILL LOOKS ON 
TRACK...ESPECIALLY WITH THE IDEA OF MINIMIZING THE MENTION OF ANY 
SHOWERS IN THE MOUNTAINS. NO ECHOES YET ON RADAR AND THE SPC MESO 
ANAL PAGE STILL SHOWS NO SBCAPE. HENCE...STILL THINK THAT CURRENT 
SLIGHT CHC POPS OVER THE HIGHEST TERRAIN IN THE MOUNTAINS WILL HOLD 
US DESPITE THE CONSIDERABLE QPF RESPONSE IN THE 12Z NAM AND GFS. ANY 
ISOLATED SHOWERS THAT DO DEVELOP SHOULD DISSIPATE QUICKLY WITH THE 
LOSS OF HEATING.

IN REGARD TO THE BIG PICTURE....THE ANOMALOUS UPPER TROUGH WILL 
REMAIN IN PLACE OVER THE EASTERN U.S THROUGH WED. AT THE 
SURFACE...COOL HIGH PRESSURE WILL REMAIN TO THE NORTH OF THE REGION. 
THESE INGREDIENTS WILL PRODUCE A COOL NIGHT ACROSS THE AREA FOR LATE 
JULY. IN FACT...OUR FORECAST IS REFLECTING TYING THE RECORD LOW FOR 
THE DATE AT AVL WHICH IS 54 SET IN 1897. ELEVATIONS ABOVE 4000 FT OR 
SO WILL SEE LOWS IN THE 40S. OUTSIDE THE MOUNTAINS...LOWS WILL BE 
MAINLY IN THE 60-65 DEGREE RANGE...EXCEPT FOR SOME 50S IN THE NC 
FOOTHILLS/NORTHERN NC PIEDMONT. NO RECORDS OUTSIDE THE MOUNTAINS 
APPEAR TO BE IN PLAY TONIGHT. THE RECORD LOW IS 58 AT CLT/63 
FORECAST AND 60 AT GSP/62 FORECAST.

WED SHOULD BE A SIMILAR DAY TO TUE WITH PARTLY TO MOSTLY SUNNY 
CONDITIONS. FORECAST SOUNDINGS ARE ESSENTIALLY CAPPED SO THE CHANCE 
OF AFTERNOON CONVECTION LOOKS TO BE EVEN LOWER ON WED. WILL ONLY 
INCREASE POPS TO SLIGHT CHANCE OVER THE SW MOUNTAINS IN THE 
AFTERNOON WHERE MODELS SHOW SOME LIGHT QPF RESPONSE. MAX TEMPS WILL 
CONTINUE TO BE A COUPLE CATEGORIES BELOW CLIMO.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...
AS OF 145 PM TUESDAY...THE UPPER TROF OVER THE EASTERN PART OF NORTH 
AMERICA WILL REMAIN THE DOMINANT WEATHER FEATURE THROUGH THE SHORT 
RANGE...BUT ITS EVOLUTION WILL HAVE IMPORTANT CONSEQUENCES. THE AXIS 
OF THE UPPER TROF SHOULD BE LOCATED OVER THE MID-ATLANTIC AND 
CAROLINAS ON WEDNESDAY NIGHT...BUT THIS WILL SHIFT TO THE MS 
RIVER/GREAT LAKES ON THURSDAY IN RESPONSE TO NEW SHORT WAVES DIGGING 
DOWN INTO THE TROF. A WEAK 850MB LOW WILL ALSO MOVE WEST WITH THE 
UPPER TROF...AND IN DOING SO...THE LOW LEVEL FLOW WILL COME AROUND 
TO SE FOR THURSDAY AND FRIDAY. ALTHO THE FLOW WILL BE LIGHT AND 
MOISTURE TRANSPORT WILL BE WEAK...THERE SHOULD BE ENOUGH MOISTURE 
RETURN TO FUEL AN INCREASE IN SHOWER COVERAGE BOTH DAYS. PRECIP 
PROBABILITY CLIMBS UP TO THE CHANCE RANGE MAINLY OVER THE MTNS AND 
FOOTHILLS FOR THURSDAY...AND THEN SOLIDLY IN THE CHANCE RANGE FOR 
FRIDAY. BOUYANCY WILL ALSO INCREASE...SO THUNDERSTORMS ARE POSSIBLE 
AGAIN FRIDAY AFTERNOON. NOT READY TO JUMP INTO THE LIKELY RANGE FOR 
FRIDAY YET. THE POSITION AND TIMING OF A VORT CENTER MOVING THROUGH 
THE REGION ON THE GFS IS VIEWED WITH A SUSPICIOUS EYE AT THIS TIME. 
TEMPS WILL REMAIN BELOW NORMAL.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 130 PM EDT TUESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON 
SATURDAY WITH THE PERSISTENT UPPER TROF AXIS OVER THE GREAT LAKES 
AND MISS RIVER VALLEY AND UPPER RIDGING OVER THE WESTERN CONUS. THE 
LONG RANGE MODELS SUGGEST THAT THE TROF WILL BEGIN TO DEAMPLIFY ON 
SUNDAY AND CONTINUE TO LIFT THRU THE REST OF THE PERIOD. THIS WOULD 
RESULT IN A SPLIT FLOW PATTERN OVER MUCH OF THE SE REGION SANDWICHED 
BETWEEN UPPER RIDGING TO THE WEST AND THE BERMUDA HIGH TO THE EAST.  

AT THE SFC...DEEPER LYR MOISTURE IS EXPECTED TO BE SPREAD OVER THE 
CWFA BY THE START OF THE PERIOD AND REMAIN OVER THE REGION THRU DAY 
7. BY SAT EVENING...THE BNDY LYR FLOW IS EXPECTED TO BECOME MORE 
SELY AND REMAIN SLY TO SELY FOR THE REMAINDER OF THE FCST PERIOD. 
PRECIP CHANCES WILL REMAIN GOOD THUR THE WEEKEND WITH POPS TAPERING 
OFF SOME FOR DAYS 6 AND 7 AS SOME DRIER AIR COULD WORK ITS WAY IN 
FROM THE NW. TEMPS SHOULD REMAIN WELL BELOW NORMAL FOR EARLY AUGUST 
WITH VALUES EXPECTED TO WARM A FEW DEGREES BY THE END OF THE PERIOD.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD AS HIGH 
PRESSURE CONTINUES TO SLIDE EAST.  LIGHT NORTHERLY FLOW WILL 
CONTINUE THROUGH THE TAF CYCLE WITH WINDS BACKING SLIGHTLY DURING 
THE AFTERNOON HOURS ON WEDNESDAY AS CENTER OF ABOVE MENTIONED 
SURFACE RIDGE PASSES BY TO THE NORTH.  FEW LOW VFR CLOUDS ARE 
POSSIBLE ACROSS THE PIEDMONT DURING THE OVERNIGHT BEFORE INCREASING 
LAPSE RATES YIELD SCT LOW VFR FAIR WX CU DURING THE AFTERNOON HOURS.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE WITH VFR CONDITIONS 
PREVAILING THROUGH THE PERIOD WITH THE EXCEPTION OF POSSIBLE MVFR 
LEVEL FOG/STRATUS AT KAVL AROUND DAYBREAK.  CONFIDENCE REMAINS LOW 
IN OCCURRENCE...THUS OPTED TO GO WITH TEMPO RATHER THAN PREVAILING.  
OTHERWISE...FAIR WX CU WILL PREVAIL THROUGH THE DAY ON WEDNESDAY 
WITH WINDS REMAINING GENERALLY LIGHT AND NORTHERLY.   

OUTLOOK...MOISTURE WILL INCREASE THROUGH THE REMAINDER OF THE WORK 
WEEK AS EAST SOUTHEASTERLY FLOW RESUMES.  THIS WILL YIELD UNSETTLED 
WEATHER WITH ENHANCED PRECIPITATION CHANCES ALONG WITH MORNING 
FOG/STRATUS THROUGH THE WEEKEND.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-05Z 
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     LOW   43%     
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     LOW   43%     
KAVL       HIGH  86%     HIGH  94%     HIGH 100%     LOW   43%     
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     LOW   43%     
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     LOW   43%     
KAND       HIGH 100%     HIGH 100%     HIGH 100%     LOW   43%     

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 JULY 30...

AVL...54 IN 1897
CLT...58 IN 1914
GSP...60 IN 1914

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...JPT
NEAR TERM...CDG/LG/SBK
SHORT TERM...PM
LONG TERM...JPT
AVIATION...CDG
CLIMATE...CDG




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