Severe Thunderstorm Warning 38, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
255 PM EDT MON MAY 11 2015

.SYNOPSIS...
THE REMNANTS OF ANA WILL CONTINUE TO MOVE NORTHEAST ALONG THE
ATLANTIC COAST TONIGHT. ON TUESDAY...A WEAK COLD FRONT WILL CROSS
OUR AREA BEFORE STRONG HIGH PRESSURE BUILDS IN FROM THE NORTH AND
REMAINS THROUGH THURSDAY. ANOTHER COLD FRONT WILL APPROACH THE REGION
ON FRIDAY.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS OF 245 PM EDT MONDAY...NEGATIVELY TILTED UPPER TROF CONTINUES TO
EJECT THROUGH THE CENTRAL PLAINS WHILE A SERIES OF SHORTWAVE
IMPULSES SLIDE THROUGH THE MEAN FLOW ALOFT OVER THE MID MISSISSIPPI
AND LOWER OHIO VALLEY REGION LEADING TO RATHER ROBUST/EXPANDING
CONVECTION ALONG/AHEAD OF A SFC COLD FRONT.  CLOSER TO HOME...MODEST
DESTABILIZATION IN THE WARM SECTOR HAS OCCURRED AS EXPECTED WITH
MOST RECENT SPC MESOANALYSIS INDICATING UPWARDS OF 2-3K J/KG SBCAPE
AMIDST LITTLE TO NO CIN.  THUS...CONVECTION CONTINUES TO FIRE ACROSS
THE HIGH TERRAIN WHERE WEAK UPSLOPING HELPS TO INITIATE ENOUGH
LIFT.  FURTHER SOUTHEAST OVER PORTIONS OF NORTHEAST GA AND THE NC/SC
PIEDMONT REGIONS...THE AIRMASS REMAINS UNSTABLE WITH LITTLE IN THE
WAY OF TRIGGERING PRESENT.  NEVERTHELESS...SOUNDINGS DUE TO SHOW
CONVECTIVE TEMPERATURES AT KGSP/KCLT IN THE MID/UPPER 80S WITH
CURRENT OBSERVED TEMPERATURES NEARING THOSE VALUES.  THEREFORE AM
EXPECTING FURTHER EXPANSION OF CONVECTION INTO THESE REGIONS LATER
THIS AFTERNOON.  WITH PWAT VALUES EXCEEDING 1-2 STD DEVIATIONS ABOVE
NORMAL...AND STORM MOTIONS GENERALLY LESS THAN 5-7KTS...CONDITIONS
ARE FAVORABLE FOR ISOLATED MINOR FLASH FLOODING WITH THE HEAVIEST
STORMS.  IN ADDITION TO THE HEAVY RAINFALL...SOUNDINGS EXHIBIT
INVERTED V CHARACTERISTICS YIELDING AMPLE DCAPE AND THUS WET
MICROBURST POTENTIAL.  THEREFORE...WILL PLAN ON KEEPING CURRENT
WORDING IN THE HWO FOR THIS PACKAGE THAT HIGHLIGHTS ALL THESE
THREATS.

CONVECTION IS EXPECTED TO DIMINISH WITH HEATING LOSS THIS
EVENING AS THE ABOVE MENTIONED COLD FRONT SLIDES THROUGH THE TN
VALLEY.  THE FRONT IS FCST TO ENTER THE HIGH TERRAIN OF WESTERN NC
AROUND 12Z TUESDAY WITH LITTLE FAN FARE...BEFORE SLIDING THROUGH
REMAINDER OF THE CWFA THROUGH THE MORNING.  SOME DESTABILIZATION
WILL OCCUR AHEAD OF THE FRONTAL AXIS AS IT SLIDES THROUGH THE
PIEDMONT REGIONS WITH LIFT ALONG THE FRONT PROVIDING A FOCUS FOR
CONVECTION.  THUS THUNDERSTORMS ARE IN THE FCST AGAIN ON TUESDAY
HOWEVER THE WITH ANY SEVERE WX EXPECTED TO RESIDE EAST OF THE REGION
WHERE SPC PLACES A MARGINAL RISK OVER THE COASTAL PLAINS OF NC/SC.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
200 PM EDT MONDAY...SHORT TERM LOOKS TO BE RATHER TRANQUIL AS
COLD FRONT SETTLES WELL SOUTH OF THE AREA AS DRY CP HIGH PRESSURE
BUILDS IN FROM THE NW. AN UPPER RIDGE IS FORECAST TO BUILD ACROSS
THE SE U.S. WED THROUGH THU. DEWPOINTS ARE FORECAST TO DROP WELL
INTO THE 40S ON WED WITH ONLY A SLOW RECOVERY ON THU INTO THE 50S AS
THE SURFACE HIGH MOVES TO THE COAST. HENCE...MOSTLY CLEAR CONDITIONS
WILL BE IN THE FORECAST TUE NIGHT THROUGH THURSDAY WITH TEMPS
LOWERING TO NEAR SEASONAL VALUES.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
215 PM EDT MONDAY...THE MEDIUM RANGE WILL BE UNSETTLED AS THE
AXIS OF THE UPPER HIGH INITIALLY MOVES EAST OF THE AREA ALONG THE
COAST. ALSO AS THE SURFACE HIGH MOVES INTO THE WESTERN
ATLANTIC...RETURN FLOW WILL TAP INTO GULF MOISTURE. MODEL TIME
HEIGHTS INDICATE THAT DEEP LAYER MOISTURE WILL ADVECT INTO THE
WESTERN CAROLINAS AND NE GA DURING FRIDAY AND REMAIN IN PLACE INTO
THE FIRST PART OF NEXT WEEK. WITH THE PERSISTENT DEEP MOISTURE IN
PLACE...MODELS AND ESPECIALLY THE GFS RESPOND WITH CONSIDERABLE QPF.
INSTABILITY IS FORECAST TO BE ON THE LOW SIDE INITIALLY ON FRI AS
PERHAPS IN-SITU CAD DEVELOPS. MODELS INDICATE THAT INSTABILITY WILL
THEN GRADUALLY INCREASE EACH AFTERNOON FROM SAT THROUGH MON.THE EC
SHOWS MORE OF A DIURNAL CYCLE TO THE QPF OVER THE WEEKEND WHICH
LOOKS MORE REASONABLE AND WILL TREND FROECAST THAT WAY. WILL RAMP UP
POPS TO CHANCE FRIDAY AFTERNOON. GUIDANCE THEN SUGGESTS THAT SOME
LIKLEY POPS WILL BE NEEDED SAT AND SUN AFTERNOONS OVER THE
MOUNTAINS. ON MONDAY...COVERAGE OF SHOWERS AND THUNDERSTORMS MAY
BECOME LESS IF UPPER RIDGE BUILDS BACK OVER THE REGION PER THE GFS.
INCREASED CLOUD COVER WILL KEEP TEMPS IN CHECK INITIALLY WITH A
REDUCED DIURNAL RANGE. MAX TEMPS ARE EXPECTED TO BE BELOW CLIMO
FRI...THEN INCREASE TO AROUND CLIMO SAT AND THEN ABOVE SUN AND MON
AS UPPER RIDGE REESTABLISHES ITSELF.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
AT KCLT...PREDOMINATELY VFR THROUGH THE PERIOD WITH THE EXCEPTION OF
POSSIBLE MVFR RESTRICTIONS RESULTING FROM AFTERNOON CONVECTION.
INITIALIZED TAF WITH MODEST SW WINDS UNDER FEW LLV CU AS LAPSE RATES
CONTINUE TO STEEPEN WITH HEATING.  FURTHER CU FIELD EXPANSION IS
EXPECTED THROUGH THE AFTERNOON...THUS PREVAIL LLV VFR CIGS AT 20Z
WITH A 4HR TEMPO FOR DEVELOPING AIRMASS TSRA YIELDING VRB 20KT
GUSTS.  ALL WX IS REMOVED NLT 01Z WITH MID LEVEL CLOUDS PREVAILING
UNDER BKN HIGH LEVEL CIGS WITH LIGHT WINDS THROUGH THE OVERNIGHT.
WINDS WILL INCREASE LATE IN THE PERIOD AS FRONTAL AXIS APPROACHES
FROM THE WEST...HOWEVER REMAINING SW WITH NO GUSTING.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE WITH AFTERNOON CONVECTION
LEADING TO POSSIBLE MVFR VISB RESTRICTIONS.  INITIALIZED ALL TAFS
WITH NO WX MENTION ASIDE FOR KAVL WHERE VCTS PREVAILED DUE TO
PROXIMITY OF CURRENT RADAR ECHOES.  NEVERTHELESS...ALL SITES HAVE
TEMPOS THIS AFTERNOON FOR ABOVE MENTIONED CONVECTION.
OTHERWISE...LOW VFR CIGS LIFT OVERNIGHT AS CONVECTION DIES DOWN AND
A COLD FRONT APPROACHES FROM THE WEST.  THUS...KEPT ALL TAFS VFR
WITH THE EXCEPTION OF LIGHT MVFR BR AT KAVL/KHKY AMIDST LIGHT/CALM
SSW FLOW.  WINDS WILL GRADUALLY START TO VEER WESTERLY NEAR PERIODS
END WITH KAVL BEING THE ONLY SITE WITH POST FROPA NW FLOW.  WINDS
WILL LIKELY BE GUSTY ALONG AND BEHIND THE FRONTAL PASSAGE ON
TUESDAY...HOWEVER BEYOND THIS TAF CYCLE.

OUTLOOK...A COLD FRONT WILL CROSS THE AREA ON TUESDAY...POSSIBLY
BRINGING ANOTHER ROUND OF DIURNAL SHRA AND TSRA. DRIER AIR WILL MOVE
IN ON WEDNESDAY...BUT THE FRONT MAY STALL JUST TO THE
SOUTH...POSSIBLY ALLOWING UNSETTLED CONDITIONS TO RETURN TO THE AREA
LATE IN THE WEEK.

CONFIDENCE TABLE...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH  96%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     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...CDG
SHORT TERM...LG
LONG TERM...LG
AVIATION...CDG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
514 AM EDT MON MAY 11 2015

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-121000-
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-
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-CHESTER-GREENWOOD-
514 AM EDT MON MAY 11 2015

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

.DAY ONE...TODAY AND TONIGHT.

THUNDERSTORMS ARE IN THE FORECAST TODAY AND TONIGHT. SOME OF
THESE THUNDERSTORMS COULD BE SEVERE...PRODUCING LARGE HAIL OR
DAMAGING WINDS. HEAVY RAINFALL COULD OCCUR WITH SOME OF THE
THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

..TUESDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..WEDNESDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..THURSDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..FRIDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..SATURDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..SUNDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

07

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
206 PM EDT MON MAY 11 2015

NCZ052-053-064-065-505-507-111830-
RUTHERFORD MOUNTAINS NC-BUNCOMBE NC-MCDOWELL MOUNTAINS NC-
TRANSYLVANIA NC-HENDERSON NC-HAYWOOD NC-
206 PM EDT MON MAY 11 2015

...A CLUSTER OF THUNDERSTORMS WILL IMPACT PORTIONS OF NORTHWESTERN
RUTHERFORD...NORTHEASTERN TRANSYLVANIA...SOUTHEASTERN BUNCOMBE...
SOUTHWESTERN MCDOWELL...SOUTHEASTERN HAYWOOD AND NORTHERN HENDERSON
COUNTIES UNTIL 230 PM EDT...

AT 204 PM EDT...DOPPLER RADAR WAS TRACKING A CLUSTER OF
THUNDERSTORMS 8 MILES SOUTH OF WEST ASHEVILLE...NEAR THE ASHEVILLE
AIRPORT...MOVING SLOWY NORTHEAST. HALF INCH HAIL...WIND GUSTS UP TO
40 MPH AND VERY HEAVY RAINFALL WILL BE POSSIBLE WITH THESE STORMS.

LOCATIONS IMPACTED INCLUDE...
BREVARD...EAST ASHEVILLE...ARDEN...ASHEVILLE AIRPORT...SKYLAND...
BLACK MOUNTAIN...MILLS RIVER...FLETCHER...SWANNANOA AND ETOWAH.

LAT...LON 3551 8210 3518 8285 3528 8292 3530 8292
      3531 8295 3535 8298 3571 8224
TIME...MOT...LOC 1804Z 240DEG 49KT 3545 8258

LG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
231 PM EDT MON MAY 11 2015

NCZ052-053-059-063>065-505-507-111915-
RUTHERFORD MOUNTAINS NC-BUNCOMBE NC-SOUTHERN JACKSON NC-
MCDOWELL MOUNTAINS NC-TRANSYLVANIA NC-HENDERSON NC-HAYWOOD NC-
NORTHERN JACKSON NC-
231 PM EDT MON MAY 11 2015

...A CLUSTER OF THUNDERSTORMS WILL IMPACT PORTIONS OF NORTHWESTERN
RUTHERFORD...EAST CENTRAL JACKSON...CENTRAL TRANSYLVANIA...
SOUTHEASTERN BUNCOMBE...SOUTHWESTERN MCDOWELL...SOUTHEASTERN HAYWOOD
AND NORTHERN HENDERSON COUNTIES UNTIL 315 PM EDT...

AT 230 PM EDT...DOPPLER RADAR WAS TRACKING A CLUSTER OF THUNDERSTORMS
11 MILES WEST OF BREVARD...OR 6 MILES SOUTHWEST OF BLACK BALSAM
AREA...MOVING SLOWLY NORTHEAST.

HALF INCH HAIL AND VERY HEAVY RAINFALL RATES UP TO 2 INCHES PER HOUR
WILL BE POSSIBLE WITH THESE STORMS.

LOCATIONS IMPACTED INCLUDE...
EAST ASHEVILLE...BREVARD...HENDERSONVILLE...WEST ASHEVILLE...DOWNTOWN
ASHEVILLE...ARDEN...ASHEVILLE AIRPORT...SKYLAND...BLACK MOUNTAIN AND
MILLS RIVER.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL MAY FLOOD AREAS WITH POOR DRAINAGE...SUCH AS
DITCHES AND UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED
ROADS. WATER LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO RISE
RAPIDLY. SEEK HIGHER GROUND IF THREATENED BY FLOOD WATERS.

&&

LAT...LON 3551 8210 3549 8211 3511 8297 3531 8308
      3569 8232
TIME...MOT...LOC 1830Z 240DEG 48KT 3525 8293

LG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
238 PM EDT MON MAY 11 2015

NCZ051-059-062-111900-
SWAIN NC-NORTHERN JACKSON NC-MACON NC-
238 PM EDT MON MAY 11 2015

...A STRONG THUNDERSTORM WILL IMPACT PORTIONS OF NORTHWESTERN
JACKSON...SOUTHEASTERN SWAIN AND NORTH CENTRAL MACON COUNTIES UNTIL
300 PM EDT...

AT 237 PM EDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 5
MILES NORTHWEST OF SYLVA...OR NEAR CHEROKEE...MOVING SLOWY
NORTHEAST.

DIME SIZE HAIL...WIND GUSTS UP TO 40 MPH AND VERY HEAVY RAINFALL
RATES UP TO 2 INCHES PER HOUR WILL BE POSSIBLE WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE...
SYLVA...DILLSBORO...CHEROKEE...COWEE...WHITTIER AND ALARKA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL MAY FLOOD AREAS WITH POOR DRAINAGE...SUCH AS
DITCHES AND UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED
ROADS. WATER LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO RISE
RAPIDLY. SEEK HIGHER GROUND IF THREATENED BY FLOOD WATERS.

&&

LAT...LON 3523 8343 3533 8352 3551 8330 3541 8319
TIME...MOT...LOC 1837Z 240DEG 48KT 3543 8329

LG