Severe Thunderstorm Warning 283, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1026 AM EDT THU AUG 1 2013

.SYNOPSIS...
A WEAK COLD FRONT WILL CROSS THE REGION TODAY...BEFORE HIGH PRESSURE
BUILDS IN FROM THE NORTHWEST FRIDAY AND LINGERS INTO SATURDAY.
ANOTHER WEAK COLD FRONT WILL PUSH IN FROM THE NORTH SUNDAY NIGHT AND
MOVE SOUTH THROUGH MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM...STRATUS IS GRADUALLY ERODING WITH DAYTIME HEATING
AND SOME DOWNSLOPE NWLY FLOW ATOP THE CLOUD LAYER. MEANWHILE...SOME
MID AND HIGH CLOUDS CONTINUE TO STREAM ACRS THE CWFA...AS AN UPR
SHORTWAVE TROF ENTERS FROM THE WEST. SO EXPECTING A MIX OF SUN AND
CLOUDS INTO EARLY AFTN. FROM THERE...FCST SNDGS INDICATE WE SHUD
DESTABILIZE TO 2000-2500 J/KG OF SBCAPE BY PEAK HEATING...ESP ALONG
THE BLUE RIDGE AND EAST. THERE SHUD BE DECENT LLVL CONVERGENCE ALONG
THE ERN SLOPES AND A LEE TROF ACRS THE PIEDMONT...KEEPING PWATS IN
THE 1.25-1.5" RANGE. SO I THINK THERE SHUD BE DECENT COVERAGE OF
SHWRS AND TSTMS ACRS THE ERN HALF OF THE CWFA. THIS IS IN LINE WITH
THE PREVIOUS FCST...SO ONLY MINOR TWEAKS TO THE POP GRIDS WERE MADE.
SOME DRY MID LVL AIR AND EFFECTIVE SHEAR OF 30-35 KTS ATOP THE MOIST
BL SHUD RESULT IN A BETTER MICROBURST THREAT WITH THE STRONGEST
CONVECTION THIS AFTN...ESP AREAS EAST OF I-85...WHERE THE BEST
INSTBY WILL BE. FREEZING LVLS ARE AROUND 14 KFT ON THE MRNG
SNDGS...SO A FIRST GUESS CORE HEIGHT (55 DBZ)IS AROUND 25.5 KFT.

TONIGHT...FRONT MAKES ITS WAY ACROSS THE CWFA WITH LOWER LLVL THETA-E
ADVECTING IN ON NWLY WINDS. POPS WILL DIMINISH TO UNMENTIONABLY LOW
VALUES BY EVENING AND SKIES WILL BECOME MOSTLY CLEAR. SFC DEWPOINTS
DON/T DROP OFF ALL THAT MUCH SO LOW TEMPS REMAIN NEAR NORMAL PIEDMONT
AND A COUPLE DEGREES BELOW NORMAL MTNS/FOOTHILLS.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 230 AM EDT THU...THE UPPER PATTERN SHOWS AN INFLUX OF H7-H5
DNVA AND FLAT RIDGING ENCOMPASSING THE AREA FRI IN SUPPORT OF A
SMALL SCALE SFC HIGH. THIS WILL BE ENOUGH TO OFFSET ANY CONVECTIVE
CHANCES AS RISING SFC PARCELS ARE SUPPRESSED BY WARM AIR ALOFT. THUS
WITH NO TRIGGERS IN THE AREA...WILL COUNT ON A DRY DAY WITH MAX
TEMPS AROUND NORMAL OR A DEGREE OR TWO ABOVE.

THE SFC HIGH BEGINS TO BREAK DOWN SAT AS UPPER HEIGHTS DROP AND
INCOMING POCKETS OF S/W ENERGY TRAVERSE THE CWFA. THE 00Z NAM IS
MORE DEFINITIVE IN A COUPLED S/W CROSSING AROUND 18Z WITH THE 00Z
GFS ON BOARD TO SOME DEGREE. THE BEST LLVL MOISTURE FLUX WILL REMAIN
SHUNTED TO THE WEST...YET SOUNDINGS INDICATE ENOUGH MLVL COOLING TO
ALLOW SOME AFTERNOON ELCAPE ACROSS MOST AREAS. WITH MECH LIFT
CONTINUING WEST...THERE WILL BE AN INCREASING CHANCE OF SHRA/TSTMS
ACROSS THE MTNS AND THE REST OF THE CWFA BY THE AFTERNOON...ENOUGH
SO TO INTRODUCE NEAR CLIMO POPS. MAX TEMPS WILL BE TRICKY DEPENDING
ON THE OVERALL CLOUDINESS...BUT LLVL THICKNESSES AND MOS SUPPORT
L90S NON/MTNS AND THE GRIDS HAVE BEEN ADJ IN THIS DIRECTION.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 305 AM EDT THU...THE EXT RANGE LOOKS TO REMAIN ACTIVE AS THE
UPPER FLOW BRINGS IN ROUNDS OF S/W ENERGY AROUND A LARGE OCCLUDED
CANADIAN SYSTEM. THE MODELS ARE HANDLING THE ERN CONUS SYNOPTIC
PATTERN DIFFERENTLY AND THE TIMING OF TWO ILL DEFINED SFC FRONTS OR
TROFS OF LOW PRESSURE EXPECTED TO AFFECT THE CWFA SUN THOUGH THE
PERIOD.

FOR NOW...WILL COUNT ON THE FIRST FRONT TO DEVELOP IN RESPONSE TO
RATHER STRONG HIGH PRESSURE MOVING SOUTH OUT OF CANADA SUN. THERE IS
A DEFINED N/S INSTABILITY GRADIENT ASSOCIATED WITH THIS FEATURE AND
THUNDER CHANCES WILL BE LIMITED TO THE SRN HALF OF THE CWFA SUN
NIGHT THROUGH MON. EXPECT THIS FRONT TO STALL OUT JUST TO THE
SOUTH...WHILE ANOTHER SFC BOUNDARY FORMS ACROSS THE OH VALLEY MON
NIGHT AND PUSHES INTO THE AREA DURING THE DAY TUE. THERE ISNT MUCH
UPPER SUPPORT WITH EITHER OF THESE FRONTS...PRETTY MUCH BACK DOOR
FRONTS...BUT DEEP CONVECTION PRODUCING STRONG TO SEVERE STORMS ARE
POSSIBLE EACH AFTERNOON MON AND TUE. THERE MAY ALSO BE A HYDRO
CONCERN WITH THE BOUNDARIES MERGING AND PERHAPS STALLING OVER THE
AREA. HOWEVER...ITS TOO EARLY TO TELL WHAT THE DEGREE OF THIS THREAT
WILL BE ATTM. WED COULD DRY OUT IN A RELATIVE SENSE WITH THE MODELS
DIVERGING A SUPPRESSIVE SFC HIGH SCENARIO. MAX TEMPS WILL GENERALLY
BE HELD A COUPLE DEGREES BELOW NORMAL THROUGH THE PERIOD...WITH MINS
AROUND NORMAL.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
AT KCLT...IFR CIG TO START THE TAF LIKELY TO HANG ON FOR AN HOUR OR
TWO AND MAY EVEN WORSEN BRIEFLY AS DEWPOINTS RISE PRIOR TO ONSET OF
MIXING. CIGS WILL SLOWLY LIFT WITH VFR CU TAKING OVER BY MIDDAY
ALONG WITH SW WINDS. FRONTAL BOUNDARY EXPECTED TO MOVE THRU IN THE
AFTN POTENTIALLY KICKING OFF NUMEROUS TSRA ACRS THE PIEDMONT. BEST
CHANCES 18-21Z THOUGH SOME ACTIVITY MAY OCCUR JUST BEFORE/AFTER THAT
PERIOD. ALSO...IF CIG PERSISTS LATER THAN EXPECTED THUNDER CHANCES
MAY BE REDUCED DUE TO INHIBITED WARMING. VFR CONDITIONS AND NW WINDS
WILL PREVAIL FOLLOWING FROPA...PERHAPS WITH SOME VERY LIGHT FOG FRI
MRNG.

ELSEWHERE...IFR CIGS SHOULD IMPROVE BY MID MORNING BUT A PATCHY
HIGHER DECK IS SEEN ON SATELLITE NEARBY...AND THIS MAY LIMIT ABILITY
OF SUN TO BURN OFF THE IFR DECK. COLD FRONT WILL MOVE THRU TODAY
FROM NW TO SE...WITH FROPA OCCURRING EARLY AFTN IN THE
MTNS/FOOTHILLS AND LATER IN THE PIEDMONT. GENERAL THINKING IS THAT
THE FRONT WILL BE TIMED TO KICK OFF THUNDERSTORMS THOUGH IT WILL NOT
NECESSARILY CLEAR OUT IMMEDIATELY BEHIND THE FRONT...AND CHANCES
REMAIN HIGHEST IN THE LOWER PIEDMONT WHERE INSTABILITY GREATEST.
FOCUSED ON PERIOD OF PEAK PRECIP CHANCES WITH TEMPOS...AND VC
MENTION SURROUNDING THAT PERIOD TO REFLECT LOWER CHANCES. ONCE
CONVECTION WANES AROUND SUNSET...VFR CONDITIONS AND NWLY WINDS
SHOULD PREVAIL FOR MUCH OF THE NIGHT...THOUGH RESTRICTIONS ARE
SUGGESTED BY GUIDANCE CONSENSUS IN THE MTNS BY EARLY FRI MRNG.

OUTLOOK...EXPECT CONDITIONS TO IMPROVE FOR THE WEEKEND AS HIGH
PRESSURE BUILDS IN BEHIND COLD FRONT.  WET CONDITIONS WILL RETURN
FOR THE START OF NEXT WEEK ASSOCIATED WITH ANOTHER FRONTAL PASSAGE.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-14Z
KCLT       HIGH  90%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH  82%     HIGH 100%     HIGH 100%     HIGH  81%
KAVL       MED   76%     HIGH 100%     HIGH 100%     HIGH  95%
KHKY       HIGH  84%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH  83%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH  84%     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...NONE.
NC...NONE.
SC...NONE.

&&

SYNOPSIS...SBK
NEAR TERM...ARK/WIMBERLEY
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...WIMBERLEY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
557 AM EDT THU AUG 1 2013

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-021000-
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-
557 AM EDT THU AUG 1 2013

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

.DAY ONE...TODAY AND TONIGHT.

A WEAK COLD FRONT WILL MOVE THROUGH THE REGION TODAY.
THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG AND AHEAD OF THIS
FEATURE. THE POTENTIAL EXISTS FOR A FEW OF THESE THUNDERSTORMS TO
PRODUCE DAMAGING WINDS AND BRIEF PERIODS OF HEAVY RAINFALL...
ESPECIALLY OVER THE PIEDMONT.

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

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

WIMBERLEY

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
939 AM EDT THU AUG 01 2013

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

0136 AM     FLASH FLOOD      2 ESE CALHOUN FALLS     34.08N 82.56W
07/10/2013                   ABBEVILLE          SC   911 CALL CENTER

            SENECA STREET IN CALHOUN FALLS FLOODED DUE TO CREEK

&&

PTANNER

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
942 AM EDT THU AUG 01 2013

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

0836 PM     FLASH FLOOD      BILTMORE FOREST         35.53N 82.54W
07/04/2013                   BUNCOMBE           NC   911 CALL CENTER

            SEVERAL STREETS FLOODED IN TOWN TO INCLUDE LYMAN
            RIVERSIDE DRIVE AMBOY ROAD..

&&

PTANNER

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
946 AM EDT THU AUG 01 2013

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

1030 PM     FLASH FLOOD      4 NE IRON STATION       35.49N 81.12W
07/09/2013                   LINCOLN            NC   911 CALL CENTER

            TRINITY FARMS NEIGHBORHOOD AMITY LANE BRIDGE WASHED OUT

&&

PTANNER