Flash Flood Warning 78, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1040 AM EDT WED AUG 7 2013

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH SUNDAY. A COLD FRONT
WILL PUSH IN FROM THE NORTH MONDAY AND BECOME STATIONARY THROUGH
TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM...CONVECTIVE COVERAGE CONTINUES TO INCREASE ACROSS THE
WRN CWFA WITH ISOLATED TO SCT COVERAGE ELSEWHERE. A WEAK SHORT WAVE
WILL MOVE ACROSS THE AREA COMBINING WITH WEAK UPPER DIVERGENCE TO
PRODUCE LARGE SCALE LIFT. SLY LOW LEVEL FLOW AND COPIOUS MOISTURE
WILL PROVIDE ADDITIONAL SUPPORT FOR CONTINUED PRECIP. THE FORCING
AND FLOW DIMINISH DURING THE AFTERNOON. THE LATEST HI-RES AND
SYNOPTIC SCALE MDLS AGREE ON INCREASING COVERAGE THRU ABOUT 18Z
THEN SLOWLY DIMINISHING COVERAGE AFTER. HAVE FOLLOWED THESE TRENDS
WITH POP INCREASING TO CATEGORICAL OVER THE WEST...WITH SCT POP
CONTINUING OVER THE EAST. FLOOD POTENTIAL CONTINUES OVER THE WRN
CWFA WHERE SLOW MOVING/TRAINING ECHOES LINGER WITH ISOLATED HEAVY
RAINFALL. KEPT HIGHS AS IS FROM PREV MAINLY DOWNWARD ADJUSTMENT.

AS OF 915 AM...IT IS BECOMING EVIDENT THAT WIDESPREAD SHRA WILL
CONTINUE OVER THE WRN UPSTATE/NE GA AND SPREAD NORTH ACROSS THE BLUE
RIDGE AND NC MTNS DURING THE MORNING. RADAR HAS SHOWN THESE TRENDS
AND THE LATEST HI-RES MDLS HAVE PICKED UP ON THIS. THEREFORE...HAVE
UPDATED THE POP TO SHOW THESE TRENDS ALONG WITH AN INCREASED CHC...
ALBEIT STILL SCT OVER THE ERN CWFA. ALTHOUGH RAINFALL HAS NOT BEEN
HEAVY...ISOLATED FLOODING IS STILL POSSIBLE GIVEN THE SLOW MOVING
CELLS. HAVE LOWERED HIGHS SOME LOCATIONS AND KEPT THEM STEADY OTHERS
GIVEN THE CLOUDS AND RAINFALL.

AS OF 640 AM EDT WEDNESDAY...HEAVY RAIN HAS WEAKENED INTO JUST LIGHT
STRATIFORM RAIN OVER NE GEORGIA. HOWEVER...THERE ARE HEAVY
STATIONARY SHOWERS AND TSTMS JUST A COUPLE COUNTIES TO OUR WEST OVER
NE GA. THE ATLANTA OFFICE HAS ISSUED A FLASH FLOOD WATCH ADJACENT TO
OUR FORECAST AREA. THIS MAKES SENSE CONSIDERING THE CURRENT
CONVECTIVE TRENDS. WE ARE GOING TO HOLD OFF FOR NOW AS THE HEAVIEST
ACTIVITY HAS NOT SHOWN ANY TENDENCY TO BUILD INTO OUR COUNTIES FOR A
WHILE NOW. LATER TODAY AS WE HEAT UP A LITTLE MORE...HOWEVER...HEAVY
RAIN COULD DEVELOP AGAIN.

AS OF 435 AM EDT WEDNESDAY...THE ATMOSPHERE WAS DETERMINED TO PROVE
ME WRONG THIS MORNING AS THUNDERSTORMS WITH HEAVY RAIN HAVE
DEVELOPED OVER NE GEORGIA. THE AREA OF RAIN IS SLOWLY DRIFTING TO
THE SOUTHEAST AND I/VE INCREASED POPS INTO THE CATEGORICAL RANGE
ALONG AND AHEAD OF IT. I TRIMMED POPS BACK A BIT IN OTHER AREAS AS
THERE ARE ONLY A FEW LIGHT SHOWERS FALLING ACROSS THE UPSTATE AND
ALONG THE BLUE RIDGE ATTM.

AS OF 300 AM EDT WEDNESDAY...WHEREAS THE LLVL FLOW WAS AROUND 30 KTS
ON THE KGSP-WSR88D WIND PROFILER LAST NIGHT...IT IS 10 KNOTS
TONIGHT. CONVECTION IS SPUTTERING ALONG THE ESCARPMENT RIGHT NOW
WITH THE WEAK LLVL WINDS. I EXPECT THAT GENERAL TREND TO CONTINUE
THROUGH SUNRISE. THAT/S TO SAY...SOME AMOUNT OF SHOWER ACTIVITY
SHOULD CONTINUE IN THIS AREA FOR SEVERAL MORE HOURS...BUT RAINFALL
AMOUNTS ARE NOT EXPECTED TO BE EXCESSIVE. WIDESPREAD CLOUDS WILL
KEEP IT COOLER THAN NORMAL TODAY AND WILL ALSO DELAY THE DEVELOPMENT
OF CONVECTION THIS AFTN. EVEN WITH LIGHT SHEAR...HIGH LAYER RH/S AND
MOIST ADIABATIC THERMAL PROFILES WILL RESULT IN A GENERALLY
UNINHIBITED ATMOSPHERE...AND SCT SHRA/TSTMS SHOULD DEVELOP ACROSS
THE REGION ONCE AGAIN. MUCH LIKE YDAY...AREAS THAT SEE THE GREATEST
SFC HEATING ARE LIKELY TO EXPERIENCE THE GREATEST CONVECTIVE
COVERAGE. I SUSPECT THAT WILL BE THE MTNS...THOUGH THAT/S NOT A HIGH
CONFIDENCE GUESS.

THE OVERNIGHT HOURS WILL SEE A WEAK TROUGH DIVE ACROSS ERN TN. THIS
FEATURE APPEARS TO BE THE RESULT OF A CONVECTIVELY INDUCED SHORT
WAVE AS WELL AS AN OVERALL WEAKNESS IN THE DEEP LAYER RIDGE OVER THE
DEEP SOUTH. FORTUNATELY THE LLVL FLOW REMAINS WEAK. THIS SHOULD ONCE
AGAIN MAKE IT DIFFICULT FOR STRONG CONVECTION TO LAST MUCH PAST
MIDNIGHT...THOUGH WE WILL PROBABLY SEE LIGHT TO MODERATE SHOWER
ACTIVITY PERSIST CLOSE TO THE MTNS INTO THU MORNING.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AT 230 AM EDT TUESDAY...A FLAT WILL EXTEND ACROSS THE SOUTHEAST
STATES ON THURSDAY AND FRIDAY...WHILE AN EASTERLY WAVE TRACKS FROM
THE CARRIBEAN TO THE GULF...AND A CLOSED UPPER LOW PROGRESSES ACROSS
SOUTHERN CANADA. THE WEST SIDE OF ATLANTIC HIGH PRESSURE WILL EXTEND
ALONG THE EASTERN SEABOARD. MOIST INFLOW WILL BE IN PLACE ON A LIGHT
SSW LOW LEVEL FLOW BOTH DAYS. ISENTROPIC UPGLIDE OVER THE SURFACE
RIDGE WILL BE RATHER WEAK...AND UPSLOPE FLOW OVER TERRAIN NOT
OPTIMAL BASED ON THE DIRECTION OF THE FLOW. NEVERTHELESS...THE SETUP
WILL SUPPORT GREATER THAN NORMAL POPS AND QPF...WITH ACTIVITY
LASTING INTO THE NIGHTS. TEMPERATURES WILL EXHIBIT A REDUCED DIURNAL
RANGE AS CLOUDS AND MOISTURE LIMIT HEATING AND COOLING.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AT 230 AM EDT TUESDAY...ON SATURDAY A FLAT UPPER RIDGE WILL STRETCH
FROM NORTHERN MEXICO TO THE ATLANTIC...WHILE AN UPPER LOW WILL BE
OVER QUEBEC. THIS PATTERN HOLDS INTO SUNDAY. ON MONDAY AN UPPER
TROUGH BEGINS TO AMPLIFY OVER THE GREAT LAKES AND NORTHEAST USA.
THIS TROUGH AMPLIFIES ALL THE WAT TO THE EASTERN GULF COAST ON
TUESDAY.

A COLD FRONT WILL SLOWLY APPROACH FROM THE NORTHWEST ON SATURDAY AND
SUNDAY...WHILE THE WEST SIDE OF ATLANTIC HIGH PRESSURE MAINTAINS A
HOLD ON THE CAROLINAS AND GA. THE COLD FRONT REACHES OUR AREA EARLY
ON MONDAY...THEN STALLS OVER OUR AREA INTO TUESDAY.

A MOIST SSW FLOW AROUND THE ATLANTIC SURFACE HIGH WILL CONTINUE TO
SUPPORT ABOVE NORMAL POPS AND QPF AHEAD OF THE FRONT...DESPITE A
LACK OF OPTIMAL UPSLOPE FLOW AND LIMITED ISENTROPIC UPGLIDE.
PRECIPITATION IS EXPECTED TO BE LESS DIURNAL IN NATURE THAN NORMAL
DUE TO THE CONTINUED MOIST INFLOW. ACTIVITY WILL INCREASE AS THE
COLD FRONT ARRIVES...AFTER WHICH THE FRONT WILL SERVE AS A FOCUS FOR
CONTINUED ACTIVITY.

TEMPERATURES WILL RUN NEAR NORMAL UNTIL THE FRONT STALLS OVER THE
AREA...WHEN BOTH HEATING AND COOLING WILL BE LIMITED BY CLOUD COVER
AND MOISTURE.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...CIGS HAVE COME UP TO VFR OVER AND NEAR THE AIRFIELD THIS
MORNING. EXPECT MAINLY VFR TO CONTINUE...WITH TEMPO RESTRICTIONS IN
ANY SHRA THE MOVE IN. LATEST GUIDANCE SHOWS LOWER PRECIP CHC OVER
THIS AREA WITH LITTLE INSTABILITY. NOT COMPLETELY SOLD ON TSRA CHC
FOR THIS AFTERNOON...BUT MAY LEAVE IN FOR CONTINUITY. SLY WIND
CONTINUES THRU THE DAY. DID NOT CARRY ANY LOWER CIGS TONIGHT. THE
GUIDANCE AND EVEN THE MODEL SOUNDINGS ARE NOT AS BULLISH ON LOW
CLOUDS. I/M NOT SAYING THEY WON/T HAPPEN...ONLY THAT I DIDN/T GET
ANYTHING LOWER THAN 3000 FEET WHEN I POPULATED MY AVIATION GRIDS.

ELSEWHERE...IFR CONTINUES XCPT MVFR AT KAVL. RAIN CHC IS MUCH HIGHER
IN THESE AREAS...SO EXPECT RESTRICTIONS INTO EARLY AFTERNOON WITH
IMPROVEMENT AS PRECIP CHC DECREASES DURING THE AFTERNOON. TSRA CHC
BETTER HERE...ESPECIALLY THE SC SITES. SLY WIND CONTINUES THRU THE
DAY. PATCHY MVFR OR IFR STATUS IS POSSIBLE TONIGHT...BUT THE
GUIDANCE WAS RATHER OPTIMISTIC ON AVERAGE SO I DIDN/T INTRODUCE
LOWER CIGS TONIGHT WITH THIS PACKAGE.

OUTLOOK...MOISTURE AND INSTABILITY CONTINUE THROUGH THE WEEKEND...
LEADING TO CONTINUED CHANCES FOR MAINLY DIURNAL CONVECTION. EARLY
MORNING PATCHY FOG AND LOW CLOUDS MAY OCCUR OVER AREAS OF RECENT
RAINFALL AND IN MTN VALLEYS.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-14Z
KCLT       MED   76%     HIGH 100%     HIGH 100%     HIGH  85%
KGSP       HIGH  83%     HIGH 100%     HIGH  92%     LOW   41%
KAVL       HIGH  94%     MED   76%     MED   65%     HIGH  88%
KHKY       MED   72%     HIGH 100%     HIGH  83%     HIGH  80%
KGMU       HIGH  90%     HIGH 100%     HIGH  92%     MED   61%
KAND       HIGH  89%     HIGH  96%     HIGH  92%     MED   66%

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...JAT
NEAR TERM...MCAVOY/RWH
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...MCAVOY/RWH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
654 AM EDT WED AUG 7 2013

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-081100-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-ALEXANDER-
IREDELL-DAVIE-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-CATAWBA-
ROWAN-GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
HENDERSON-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-UNION NC-
CALDWELL MOUNTAINS-GREATER CALDWELL-BURKE MOUNTAINS-GREATER BURKE-
MCDOWELL MOUNTAINS-EASTERN MCDOWELL-RUTHERFORD MOUNTAINS-
GREATER RUTHERFORD-POLK MOUNTAINS-EASTERN POLK-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-GREATER OCONEE-
GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-CHEROKEE-YORK-
ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
654 AM EDT WED AUG 7 2013

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

.DAY ONE...TODAY AND TONIGHT.

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER THE REGION
AGAIN TODAY. AS THE STORMS WILL BE SLOW MOVING...LOCALLY EXCESSIVE
RAINFALL AND ISOLATED FLASH FLOODING WILL BE POSSIBLE.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

14

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
642 AM EDT WED AUG 07 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1130 AM     FLASH FLOOD      2 E BELTON              34.52N 82.47W
08/06/2013                   ANDERSON           SC   PUBLIC

            BLAKE DAIRY ROAD FLOODED AT BROAD MOUTH CREEK.

&&

07

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
707 AM EDT WED AUG 07 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1134 PM     FLASH FLOOD      4 W NORRIS              34.77N 82.82W
08/06/2013                   PICKENS            SC   911 CALL CENTER

            TODDS CREEK WASHED OUT SUNRISE RD

&&

PTANNER

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
709 AM EDT WED AUG 07 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1056 PM     FLASH FLOOD      5 NW CENTRAL            34.78N 82.85W
08/06/2013                   PICKENS            SC   911 CALL CENTER

            6 MILE CREEK FLOODS JONES MILL ROAD

&&

PTANNER