Flash Flood Warning 82, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
241 PM EDT THU AUG 8 2013

.SYNOPSIS...
MOIST SOUTHERLY FLOW WILL REMAIN ACROSS THE REGION THROUGH SATURDAY
KEEPING CHANCES FOR SHOWERS AND THUNDERSTORMS ENHANCED.  A COLD
FRONT WILL MOVE INTO THE AREA FROM THE NORTH LATE ON SATURDAY INTO
SUNDAY MORNING KEEPING RAIN CHANCES ELEVATED THROUGH TUESDAY AS IT
SLOWLY MIGRATES SOUTHWARD. SOUTHERLY FLOW WILL RETURN BY WEDNESDAY
ALLOWING FOR A GRADUAL WARMING TREND AND INCREASING MOISTURE.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 235 PM EDT...THE FORECAST AREA WILL REMAIN IN MOSTLY ZONAL
FLOW BETWEEN SHALLOW HIGH PRESSURE ACROSS THE DEEP SOUTH AND A
BETTER BELT OF WESTERLIES FROM THE OH VALLEY NORTHWARD THROUGH THE
NEAR TERM. WEAK MID AND UPPER VORTICITY LOBES WILL CROSS THE AREA
THROUGH THE PERIOD...WITH SLIGHTLY BETTER FORCING AFFECTING THE NRN
TIER. AT LOWER LEVELS...S TO SW FLOW IN THE BOUNDARY LAYER WILL
CONTINUE TO TRIGGER SHOWERS AND TSTMS IN A MOSTLY DIURNAL PATTERN IN
THE MOST SOUTHERLY UPSLOPE FLOW PRONE LOCATIONS. INSTABILITY HAS
STAYED SOMEWHAT LIMITED DUE TO THE CLOUD COVER AND MOIST PROFILES
TODAY...SO ANY SEVERE TSTM THREAT WILL BE QUITE MARGINAL.
HOWEVER...HIGH PRECIPITABLE WATER VALUES AROUND 2 INCHES IN MORNING
RAOBS AND MODEL SOUNDINGS...WARM CLOUD LAYERS OF GENERALLY 12 TO 13
KFT...AND MBE VECTORS LESS THAN 10 KT WILL KEEP THE ISOLATED FLASH
FLOOD THREAT FAIRLY HIGH WITH ANY TRAINING CELLS. WE PLAN ON NO
CURRENT CHANGES TO THE FLASH FLOOD WATCH SINCE THE CURRENT WATCH
AREA APPEARS TO STILL HAVE THE BEST OVERLAP OF FOCUSED...TRAINING
POTENTIAL ALONG WITH SATURATED ANTECEDENT CONDITIONS.

DESPITE THE ABUNDANT...LINGERING MOISTURE AND WEAK...SPORADIC UPPER
WAVE ENERGY OVERNIGHT PRECIP COVERAGE SHOULD GRADUALLY TREND DOWN
OVERNIGHT AS THE MODEL PROFILES QUICKLY DEVELOP A LARGE NEGATIVE
BOUYANCY AREA FROM MID EVENING ONWARD. ANTICIPATE LOW CLOUDS AND FOG
DEVELOPING TOWARD DAYBREAK...BUT THE FOG SHOULD NOT BE PARTICULARLY
DENSE OUTSIDE OF ANY MOUNTAIN RIVER VALLEYS. EXPECT MIN TEMPS ABOVE
GUIDANCE GIVEN THE CLOUD COVER AND RECENT PERFORMANCE.

PROFILES REMAIN MOIST FRI WITH MODEL PWAT VALUES AROUND 2 INCHES
ALONG WITH FAIRLY WEAK STEERING FLOW. IT IS POSSIBLE THAT 850 MB
FLOW MAY BECOME A BIT MORE WESTERLY...AND THIS SLIGHT VEERING COULD
RELIEVE SOME OF THE SRLY UPSLOPE AREAS OF THE BEST CONVECTIVE PRECIP
FOCUS. HOWEVER...BL WINDS MAY CONTINUE MORE SW THROUGH FRI AFTN.
ONCE AGAIN...AN ISOLATED FLASH FLOOD THREAT WILL CONTINUE. WILL
FEATURE MAX TEMPS BELOW GUIDANCE GIVEN THE CLOUD COVER AND RECENT
VERIFICATION.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
AS OF 200 PM EDT...CHANCES FOR SHOWERS AND THUNDERSTORMS WILL TAPER
OFF SLIGHTLY DURING THE OVERNIGHT HOURS FRIDAY EVENING AS DAYTIME
HEATING FADES.  THUS...LOWERED POPS TO CHANCE LEVELS ACROSS THE AREA
WITH THE HIGHEST SOLID CHANCE POPS BEING ALONG THE HIGH TERRAIN
WHERE UPSLOPE FLOW WILL PROLONG THE ACTIVITY.  FOR SATURDAY...WEAK
COLD FRONT ASSOCIATED WITH UPPER LOW LOCATED OVER EASTERN CANADA
WILL BE ORIENTED FROM WEST TO EAST AND MOVING SLOWLY OUT OF THE OHIO
VALLEY AND INTO THE TENNESSEE VALLEY REGION.  MEANWHILE...DEEP
MOISTURE FETCH WILL REMAIN IN PLACE ACROSS THE SOUTHEASTERN UNITED
STATES AS BERMUDA HIGH DOMINATE THE FLOW.  MODEL GUIDANCE REMAINS IN
GOOD AGREEMENT WITH REGARDS TO A DIURNAL TYPE TREND TO THE
CONVECTION ON SATURDAY.  THERE WILL BE ENHANCEMENTS OVER THE HIGH
TERRAIN AS LOW LEVEL FLOW CONTINUES TO PROMOTE UPSLOPE COMPONENTS.
THEREFORE...HIGHLIGHTED SOLID CHANCE POPS ACROSS THE UPSTATE AND
NORTHEAST GA REGIONS WITH LIKELY POPS PREVAILING ACROSS MUCH OF
WESTERN NC.  AS THE ABOVE MENTIONED SURFACE FRONT MOVES CLOSER TO
THE REGION...WOULD NOT BE SURPRISED TO SEE SOME ADDITIONAL
ENHANCEMENT ALONG THE BOUNDARY ACROSS NORTHWEST NC.  DUE TO THE
AMOUNT OF ABUNDANT MOISTURE IN THE PROFILE YIELDING ABOVE CLIMO
PRECIPITABLE WATERS...THINK THE MAIN THREAT SATURDAY WILL BE
LOCALIZED HEAVY RAINFALL AS STEERING FLOW REMAINS WEAK.

MUCH OF THE SAME FOR SUNDAY AS QUASI STATIONARY SURFACE BOUNDARY
REMAINS DRAPED ACROSS THE SOUTHERN APPALACHIANS.  MOISTURE CONTENT
THROUGH THE PROFILE WILL REMAIN HIGH...YET SLIGHTLY LESS THAN
PREVIOUS DAYS AS LOW LEVEL FLOW SHIFTS MORE WESTERLY.  WITH THAT
BEING SAID...KEPT NEARLY THE SAME POP FORECAST AS SATURDAY WITH
LIKELY POPS RESIDING ACROSS MUCH OF WESTERN NC AND CHANCE POPS
ELSEWHERE.  DUE TO SLIGHTLY LESS SKY COVER ACROSS THE REGION ON
SUNDAY...WOULD NOT BE SURPRISED TO SEE GREATER INSTABILITY AS MORE
SUNSHINE ALLOWS FOR ADDITIONAL HEATING.  THUS...SOME SCATTERED
AFTERNOON THUNDERSTORMS ARE POSSIBLE.  TEMPERATURES THROUGH THE
SHORT TERM PERIOD WILL REMAIN AT OR SLIGHTLY BELOW NORMAL.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 230 PM EDT...SURFACE FRONTAL BOUNDARY WILL MOVE SOUTHWARD INTO
THE LOW COUNTRY AND DRAPE WESTWARD ACROSS THE MID GULF COAST
STATES ON MONDAY.  MEANWHILE...SLIGHTLY DRIER AIR WILL WORK ITS WAY
IN ACROSS THE REGION FOR THE START OF THE WORK WEEK.
HOWEVER...WESTERLY LOW LEVEL FLOW WILL ALLOW FOR ENHANCED UPSLOPE
CONVECTION ACROSS THE HIGH TERRAIN ON MONDAY WHERE LIKELY POPS WILL
PREVAIL.  THE ABOVE MENTIONED BOUNDARY WILL PROVIDE A FOCUS FOR
THUNDERSTORM ACTIVITY ACROSS THE MIDLANDS AND PERHAPS INTO THE
UPSTATE OF SC THROUGH MIDWEEK.   KEPT ABOVE CLIMO POPS IN THE
FORECAST THROUGH THE REMAINDER OF THE PERIOD AS SOUTHERLY FLOW
GRADUALLY RETURNS ALLOWING FOR INCREASING MOISTURE ACROSS THE AREA.
TEMPERATURES THROUGH THE EXTENDED PERIOD WILL REMAIN A FEW DEGREES
BELOW NORMAL.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AT KCLT...THE LATEST HRRR MODEL RUN HAS CAPTURED THE LINE OF WEAK
CONVECTION W OF THE AIRFIELD THIS AFTN. STILL NOT SEEING ANY
LIGHTNING WITH THIS...BUT TEMPO TSRA WAS MOVED UP TO 19Z TO ACCOUNT
FOR EARLIER TRIGGERING AS THIS ACTIVITY MOVES E. GIVEN THE LOW
LCL/CCL...CIGS WILL LIKELY REMAIN LOWER VFR AND QUICKLY TOGGLE OVER
INTO MVFR WITH ANY SHOWERS AT THE AIRFIELD. CANNOT RULE OUT SOME
BRIEF IFR VSBY WITH ANY HEAVIER DOWNPOURS BUT CONFIDENCE IS TOO LOW
TO FORECAST THAT. ANTICIPATE COVERAGE TO DWINDLE GRADUALLY LATE THIS
EVENING THROUGH THE OVERNIGHT...WITH RESONABLE CHANCES OF AT LEAST
MVFR RESTRICTIONS EARLY FRI GIVEN THE LOW LEVEL MOISTURE. WILL
REINTRODUCE VCSH ALONG WITH GRADUAL IMPROVEMENT INTO VFR LATE FRI
MORNING AND WILL HOLD OFF ON ANY FRI THUNDER POTENTIAL UNTIL AFTER
18Z. WINDS SHOULD REMAIN SW AT LESS THAN 10 KT THROUGH THE
PERIOD...ASIDE FROM ANY TSTMS.

ELSEWHERE...COVERAGE OF WEAK CONVECTION IS GRADUALLY FILLING IN
ACROSS THE REGION THIS AFTN. HAVE STARTED TEMPO TSRA EARLIEST AT
KAVL...BUT WILL NEED SOME MENTION BY ABOUT 19Z AT THE FOOTHILL TAF
SITES AS WELL. EXPECT CIGS TO ALTERNATE BETWEEN MVFR AND VFR THROUGH
LATE DAY...WITH BRIEF IFR CONDITIONS POSSIBLE WITH ANY HEAVY
DOWNPOURS. COVERAGE WILL GRADUALLY DIMINISH TONIGHT...WITH A RETURN
OF MVFR CIGS LIKELY BY DAYBREAK AT THE UPSTATE TAFS...IFR AT KAVL BY
09Z...AND TEMPO IFR AT KHKY AT TIMES. EXPECT SLOW IMPROVEMENT
THROUGH LATE MORNING WITH VCSH RETURNING TO THE FORECAST. WILL ONLY
MENTION PROB30 FOR TSRA AT KAVL PRIOR TO 18Z GIVEN THE EARLIEST MTN
ONSET WITH TERRAIN UPSLOPE. EXPECT MAINLY LIGHT SW WINDS THROUGH THE
PERIOD...EXCEPT VRB NEAR TSTMS.

OUTLOOK...DEEP MOISTURE AND DAILY SHOWER/TSTM TRIGGERING WILL
CONTINUE THROUGH THE WEEKEND. IFR TO MVFR RESTRICTIONS LOOK LIKELY
LATE EACH NIGHT/EARLY EACH MORNING...WITH ADDITIONAL RESTRICTIONS
UNDER ANY CONVECTION. CONDITIONS MAY STAY UNSETTLED THROUGH EARLY
NEXT WEEK DEPENDING ON THE SWD PROGRESS OF A WEAK FRONT THROUGH THE
AREA.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     MED   76%     MED   79%
KGSP       HIGH 100%     MED   78%     LOW   58%     MED   75%
KAVL       MED   76%     MED   62%     MED   67%     MED   69%
KHKY       MED   74%     MED   64%     MED   68%     HIGH  87%
KGMU       HIGH  97%     MED   71%     LOW   58%     MED   70%
KAND       HIGH  97%     HIGH 100%     MED   75%     MED   65%

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...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR GAZ010-017-018-026-
     028-029.
NC...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR NCZ062>065-509-510.
SC...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR SCZ001>007-010>012-
     019.

&&

SYNOPSIS...CDG
NEAR TERM...HG
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...HG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1119 AM EDT THU AUG 8 2013

GAZ010-017-018-026-028-029-NCZ062>065-509-510-SCZ001>007-010>012-019-
091530-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-MACON-SOUTHERN JACKSON-
TRANSYLVANIA-HENDERSON-POLK MOUNTAINS-EASTERN POLK-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-GREATER OCONEE-
GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-ANDERSON-ABBEVILLE-
LAURENS-GREENWOOD-
1119 AM EDT THU AUG 8 2013

...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...WESTERN
NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   FLASH FLOOD WATCH.

IN ADDITION TO THE HEAVY RAIN THREAT...NUMEROUS THUNDERSTORMS
WILL DEVELOP THIS AFTERNOON INTO TONIGHT WHICH WILL PRODUCE
OCCASIONAL CLOUD TO GROUND LIGHTNING AND BRIEFLY GUSTY WINDS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...OR FLASH FLOODING TO OUR OFFICE.

NCZ033-035>037-048>053-056>059-068>072-082-501>508-SCZ008-009-013-
014-091530-
AVERY-ALEXANDER-IREDELL-DAVIE-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-
BUNCOMBE-CATAWBA-ROWAN-GRAHAM-NORTHERN JACKSON-CLEVELAND-LINCOLN-
GASTON-MECKLENBURG-CABARRUS-UNION NC-CALDWELL MOUNTAINS-
GREATER CALDWELL-BURKE MOUNTAINS-GREATER BURKE-MCDOWELL MOUNTAINS-
EASTERN MCDOWELL-RUTHERFORD MOUNTAINS-GREATER RUTHERFORD-CHEROKEE-
YORK-UNION SC-CHESTER-
1119 AM EDT THU AUG 8 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PIEDMONT NORTH
CAROLINA...WESTERN NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED THIS
AFTERNOON INTO TONIGHT. SOME OF THE THUNDERSTORMS WILL PRODUCE
LOCALLY VERY HEAVY RAINFALL...RESULTING IN THE THREAT OF ISOLATED
FLASH FLOODING. OCCASIONAL CLOUD TO GROUND LIGHTNING STRIKES AND
BRIEFLY GUSTY WINDS ARE POSSIBLE AS WELL.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...OR FLASH FLOODING TO OUR OFFICE.

GERAPETRITIS