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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
523 PM EDT THU JUL 2 2015

.SYNOPSIS...
A BROAD UPPER LEVEL TROUGH WILL REMAIN OVER THE SOUTHEAST THROUGH 
THE WEEKEND...STEERING A SERIES OF WEAK LOW PRESSURE SYSTEMS OVER 
THE REGION. THESE SYSTEMS WILL INCREASE RAIN AND THUNDERSTORM 
CHANCES EACH AFTERNOON AND EVENING. SLIGHT DRYING WILL OCCUR ON 
MONDAY AND TUESDAY...BEFORE ANOTHER FRONT PUSHES THROUGH LATE NEXT 
WEEK. HIGH TEMPERATURES WILL BE NEAR NORMAL THROUGH NEXT WEEK...WITH 
LOWS JUST ABOVE NORMAL.

&&

.NEAR TERM /THROUGH FRIDAY/...
515 PM EDT UPDDATE...MOST SHOWERS HAVE EXITED THE AREA TO THE SOUTHEAST 
WITH SOME RESIDUAL LIGHT RAIN.  MADE SUBSTANTIAL CHANGES TO THE NEAR 
TERM PRECIP FORECAST TO ACCOUNT FOR THE ABSENCE OF PRECIP IN MOST 
AREAS...NEGATIVE RADAR TRENDS...AND SUPPORT FROM THE HRRR TO KEEP 
THE NEXT ROUND OF PRECIP OUT UNTIL MIDNIGHT.  ALSO UPDATED 
TEMPERATURES DUE TO CONSIDERABLE RAIN COOLING IN SOME AREAS AND 
EXTENSIVE CLOUD COVER HOLDING TEMPERATURES DOWN.

AS OF 245 PM EDT...AN OUTFLOW FROM EARLIER CONVECTION WORKING 
SOUTHWARD OVER THE WESTERN AND SOUTHERN PART OF THE CWFA HAS 
ENCOUNTERED INCREASED INSTABILITY...WITH 1500 TO 2000 J/KG OF SBCAPE 
OVER THE UPSTATE AND NE GA THIS AFTN. POPS HAVE BEEN RATCHETED 
ACROSS THE SRN THIRD OF THE FORECAST AREA FOR A FEW HOURS THIS 
AFTERNOON...AND HAVE CONTINUED TO BACK AWAY FROM THE HIGHER POPS 
PREVIOUSLY INDICATED BY THE MESOCALE MODELS FOR CONVECTION COMING 
OFF THE BLUE RIDGE INTO THE NC FOOTHILLS AND PIEDMONT. THIS IS 
POSSIBLY JUST THE FIRST WAVE OF MANY...AS ADDITIONAL SHORTWAVES 
EMBEDDED IN THE H5 TROUGH WILL CROSS THE FORECAST AREA LATER THIS 
AFTERNOON AND EARLY THIS EVENING.

YET MORE VORTICITY LOBES WILL CROSS THE BASE OF THE SOUTHERN 
APPALACHIANS LATER TONIGHT THROUGH FRIDAY AS THE TROUGH DEEPENS TO 
THE WEST FROM THE LOWER OH VALLEY TO THE MS RIVER VALLEY. WESTERLY 
850 MB FLOW WILL INCREASE TONIGHT THROUGH FRI ACROSS THE SRN TIER AS 
THE 850 MB LOW CENTER DEEPENS SLIGHTLY OVER THE OH VALLEY. THE 
FORECAST AREA WILL STAY SOLIDLY WARM SECTOR THROUGH THE NEAR TERM 
PERIOD AS A SURFACE WAVE MOVES ALONG THE STALLED BOUNDARY FROM THE 
LOWER OH VALLEY THROUGH THE CENTRAL APPALACHIANS. ANTICIPATE A 
SMALLER THAN USUAL DIURNAL RANGE ON TEMPS WITH PLENTY OF 
CLOUDS/DEBRIS...AND WILL NEED TO SHOTGUN HIGH CHANCE TO LOW END 
LIKELY POPS FOR MUCH OF THE AREA BEYOND THE IMMEDIATE NEAR TERM 
GIVEN THE MULTIPLE SHORTWAVES AND MOIST PROFILES. EXPECT GUSTY WINDS 
WITH MIXING AGAIN ON FRI AFTN. HEAVY RAIN WILL POSE A LOCALIZED 
HYDRO THREAT JUST ABOUT ANYWHERE THAT TRAINING OCCURS...WITH THE SW 
MTNS STANDING THE BEST CHANCE OF FLOODING. CONFIDENCE REMAINS TOO 
LOW FOR A FLASH FLOOD WATCH SINCE COVERAGE WILL BE HIGHEST IN THE 
WESTERN MTNS BUT RATES WILL BE BETTER IN MORE UNSTABLE AREAS.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 250 PM THURSDAY...UPPER TROUGH AXIS WILL REMAIN POSITIONED 
WEST OF THE FORECAST AREA THROUGH THE WEEKEND...WITH UNSEASONABLY 
HIGH PWATS (GENERALLY 1-2 STANDARD DEVIATIONS ABOVE CLIMO) THROUGH 
THE PERIOD. A SERIES OF WEAK SHORT WAVE MOVING THROUGH THE TROUGH 
AXIS WILL SUPPORT HIGHER-THAN-CLIMO POPS THROUGH THE PERIOD...WITH 
AT LEAST GOOD CHANCES FOR CONVECTION PERSISTING INTO THE NOCTURNAL 
HOURS. THIS WILL ESPECIALLY BE TRUE ON SAT NIGHT...AS THE MOST 
SIGNIFICANT SHORT WAVE (POSSIBLY DEVELOPING INTO A CLOSED LOW) NEARS 
THE AREA. HIGH CHANCE TO LIKELY POPS WILL BE CARRIED IN ALL AREAS... 
MAINLY FROM SAT AFTERNOON THROUGH SUNDAY AFTERNOON. MOIST 
THERMODYNAMIC PROFILES AND RATHER EXTENSIVE CLOUD COVER WILL LIMIT 
CAPE THROUGH THE PERIOD...AND THE SEVERE THREAT SHOULD REMAIN HIGHLY 
LOCALIZED THROUGH THE PERIOD. HOWEVER...WITH PWATS REMAINING 
ELEVATED... THE THREAT FOR LOCALLY HEAVY AND POSSIBLY EXCESSIVE 
RAINFALL WILL BE POSSIBLE THROUGH THE PERIOD. THIS THREAT IS 
EXPECTED TO BE MOST PREVALENT ACROSS THE FAR WESTERN NC MTNS...WHERE 
WESTERLY LOW LEVEL FLOW WILL SUPPORT UPSLOPE ENHANCEMENT TO COVERAGE 
OF CONVECTION AND PRECIP RATES. ANTECEDENT CONDITION WILL PROBABLY 
ALSO GRADUALLY DETERIORATE IN THOSE AREAS OVER THE NEXT 2-3 DAYS AS 
WELL.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 230 PM THURSDAY...THE MEDIUM RANGE BEGINS 00Z MONDAY WITH THE 
AREA IN AN UPPER LEVEL SPLIT-FLOW REGIME. A QUASI-STATIONARY 
BOUNDARY WILL BE LOCATED JUST TO THE SOUTH OF THE FORECAST 
AREA...PROVIDING A FOCUS FOR DIURNALLY ENHANCED POPS THAT EXTENDS 
ACROSS THE SOUTHERN APPALACHIANS. THE INFLUENCE OF THE BERMUDA HIGH 
AND PERSISTENT SOUTHWESTERLY FLOW WILL KEEP DEEP LAYER MOISTURE 
PLENTIFUL THROUGHOUT THE PERIOD...THOUGH THERE DOES APPEAR TO BE 
SOME RELATIVE SLIGHT DRYING OF THE AIRMASS ON MONDAY AND TUESDAY. 
DIURNAL POPS NEAR TO JUST ABOVE CLIMO WILL BE PRESENT BOTH DAYS. ON 
WEDNESDAY...WEAK UPPER LEVEL TROUGHING WILL BEGIN TO BUILD BACK INTO 
THE FORECAST AREA AS AN UPPER LOW AND ASSOCIATED FRONTAL BOUNDARY 
TAKE SHAPE OVER THE SOUTHEAST...AND PWATS CLIMB BACK OVER 2 INCHES. 
POPS ARE THEREFORE ABOVE CLIMO TOWARD THE END OF THE PERIOD...AND DO 
NOT WANE MUCH OVERNIGHT. INSTABILITY DOES NOT APPEAR SPECTACULAR FOR 
ANY DAY IN THE MEDIUM RANGE...BUT PLENTIFUL DEEP LAYER MOISTURE 
THROUGHOUT THE ENTIRE FORECAST PERIOD WILL MEAN THAT 7-DAY QPF 
TOTALS BEAR WATCHING.

DESPITE HEIGHT RISES THROUGHOUT THE MEDIUM RANGE...MOIST PROFILES 
AND ASSOCIATED CLOUD COVER WILL KEEP MAX TEMPS HOVERING AROUND 
CLIMO. MIN TEMPS WILL BE NEAR TO JUST ABOVE CLIMO.

&&

.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
AT KCLT...CONVECTION DEVELOPING ON THE EARLY DAY MCS OUTFLOW IS 
EXTENDING EAST TOWARD THE KCLT VICINITY THIS AFTN. THE CURRENT TEMPO 
TSRA FROM 19Z STILL LOOKS WELL TIMED WITH ASSOCIATED MVFR 
RESTRICTIONS UNDER ANY HEAVY THUNDER SHOWERS. ANTICIPATE LOW END 
GUSTS IN BOTH THE GRADIENT FLOW WITH MIXING AND IN ANY TSTMS WITH 
LIMITED DCAPE. THE NAM REMAINS MOST BULLISH ON OVERNIGHT MVFR CLOUDS 
DEVELOPING...BUT THE MOS REMAINS UNEXCITED. WILL HOLD OFF FOR NOW 
GIVEN THE LIKELIHOOD OF CONSIDERABLE MID/HIGH DEBRIS CLOUDS. GIVEN 
THE MULTIPLE PASSING SHORTWAVES...SHOWERS OR ISOLD TSTMS WILL 
CONTINUE TO POSSIBLE AT JUST ABOUT ANY TIME OVERNIGHT THROUGH FRIDAY 
MORNING...BUT WITH A BETTER CHANCE FROM MID MORNING ON FRIDAY.

ELSEWHERE...TEMPO TSRA WITH 20 TO 30 KT GUSTS LOOKS HIGHLY LIKELY AT 
THE UPSTATE SITES ALONG THE OUTFLOW LINE THIS AFTN...WITH PRECIP 
GENERALLY MORE SHOWERS FROM KAVL TO KHKY. ANTICIPATE CONTINUED 
ROUNDS OF SHOWERS WITH PASSING UPPER SHORTWAVES TONIGHT THROUGH 
FRIDAY MORNING...WITH SCATTERED TSTMS POSSIBLE AT ANY TIME AS WELL. 
WE COULD SEE A REPEAT OF SPOTTY LOW STRATUS AGAIN FRI MORNING GIVEN 
ALL THE MOISTURE AROUND...BUT THERE WILL ALSO BE PLENTY OF MID/HIGH 
DEBRIS CLOUDS. WILL CONFINE THE OVERNIGHT RESTRICTIONS TO KAVL AND 
KHKY FOR NOW. EXPECT UPSTATE TAF SITES TO START GUSTING AGAIN LATE 
IN THE PERIOD AS MIXING GRADUALLY IMPROVES AND 850 MB WESTERLY WINDS 
INCREASE.

OUTLOOK...A GRADUALLY WEAKENING UPPER TROUGH WILL SUPPORT MAINLY 
AFTERNOON AND EVENING THUNDERSTORMS THROUGH EARLY NEXT WEEK. 
RESTRICTIONS MAY OCCUR WITH PASSING STORMS...AND EACH MORNING OVER 
RAIN SOAKED AREAS.

CONFIDENCE TABLE...

            21-03Z        03-09Z        09-15Z        15-18Z 
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  80%     
KGSP       HIGH 100%     HIGH 100%     HIGH  92%     HIGH  95%     
KAVL       HIGH 100%     HIGH 100%     MED   71%     HIGH  80%     
KHKY       HIGH 100%     HIGH 100%     HIGH  85%     HIGH  87%     
KGMU       HIGH 100%     HIGH 100%     HIGH  90%     HIGH  92%     
KAND       HIGH 100%     HIGH 100%     HIGH  90%     HIGH  97%     

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...LEV
NEAR TERM...HG/WJM
SHORT TERM...JDL
LONG TERM...LEV
AVIATION...HG

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