Severe Thunderstorm Warning 31, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
251 PM EDT SUN MAY 19 2013

.SYNOPSIS...
A WEAK UPPER LEVEL TROUGH WILL SWING EAST OVER THE REGION THROUGH
MONDAY. THE FORECAST AREA WILL REMAIN IN A MOIST AND RATHER UNSTABLE
AIRMASS...BEFORE A COLD FRONT CROSSES THROUGH LATE IN THE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
CONVECTIVE COVERAGE CONTINUES TO INCREASE AS EXPECTED ACROSS THE NC
PIEDMONT THIS AFTERNOON WITHIN LOW LEVEL CONFLUENCE AXIS ACTING UPON
A MODERATELY UNSTABLE/VERY MOIST AIR MASS. FARTHER WEST...EXPANSIVE
CIRRUS SHIELD ASSOCIATED WITH TENN VALLEY CONVECTION...AS WELL AS
OUTFLOW FROM THIS MORNING/S CONVECTION HAS LARGELY STABILIZED THE
ATM ACROSS THE UPPER SAVANNAH RIVER VALLEY. MEANWHILE...TENN VALLEY
CONVECTION HAS MOSTLY BEEN STRUGGLING TO MAKE ITS WAY INTO THE
SOUTHERN APPALACHIANS...AS IT IS BEING FUELED BY THE VERY UNSTABLE
AIR TO ITS WEST/SOUTHWEST. HOWEVER...SCATTERED CONVECTION HAS BEGUN
INITIATING OVER THE HIGHER TERRAIN...LIKELY ASSISTED BY OUTFLOW
BOUNDARIES AS WELL AS DIFFERENTIAL HEATING ACROSS THE EDGE OF THE
CIRRUS SHIELD. WILL CONTINUE TO FEATURE LIKELY/CAT POPS THROUGH THIS
EVENING ACROSS WESTERN AREAS. LOCALLY HEAVY/PERHAPS EXCESSIVE
RAINFALL WILL BE THE PRIMARY THREAT...BUT SOME PULSE SEVERE STORMS
CANNOT BE RULED OUT. THE PRIMARY THREAT AREA FOR HEAVY RAIN MAY
PROVE TO BE THE I-77 CORRIDOR...AS PERSISTENT CONFLUENT ZONE COULD
SUPPORT REPEATED DEVELOPMENT/TRAINING OF CELLS.

AS THE WEAKENING UPPER TROUGH AXIS CONTINUES TO SLOWLY PUSH EAST
ACROSS THE AREA THIS EVENING...DRIER MID-LEVEL AIR WILL BEGIN TO
ADVECT INTO WESTERN ZONES...WHICH SHOULD ALLOW THE FOCUS FOR
CONVECTION TO SHIFT TO EASTERN AREAS. AN OVERALL DOWNWARD TREND IN
COVERAGE IS EXPECTED OVERNIGHT...ESPECIALLY ACROSS THE EASTERN
ZONES.

FOR MONDAY...DRIER AIR SHOULD SPELL MORE CLEARING/BETTER INSOLATION
AND THEREFORE IMPROVED INSTABILITY BY AFTERNOON...ESP ACROSS THE
WEST. AS A RESULT...CONVECTION SHOULD FIRE ACROSS THE HIGHER TERRAIN
DURING THE AFTERNOON. ALTHOUGH COVERAGE SHOULD BE LESS THAN TODAY...
IMPROVED INSTABILITY SHOULD LEAD TO MORE VIGOROUS UPDRAFTS...AND A
GREATER THREAT FOR ISOLATED PULSE SEVERE STORMS. TEMPS WILL BE ABOVE
NORMAL THROUGH THE PERIOD.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
SFC/UPPER RIDGE REMAINS FIXED OVER THE WRN CAROLINAS AND NE GEORGIA
MON NIGHT AND TUESDAY KEEPING THE REGION DEVOID OF ANY SIGNIFICANT
FORCING...WITH WEAK WINDS THROUGHOUT THE COLUMN. THOUGH THE THERMAL
GRADIENT IS QUITE WEAK IN THE LOW-MID LEVELS THERE IS SOME SLIGHT WAA
MON NIGHT...WHICH ALONG WITH SUBSIDENCE UNDER THE RIDGE LOOKS TO
PRODUCE ENOUGH CAPPING TO PRECLUDE ANY OVERNIGHT CONVECTION.
SOUNDINGS DO REMAIN SOMEWHAT FAVORABLE INTO MON EVENING MAINLY IN THE
ERN ZONES...BUT ALL ACTIVITY SHOULD DIMINISH BY MIDNIGHT OR SO.
SKIES SHOULD CLEAR ENOUGH TO ALLOW FOR QUICK HEATING ON TUE AND
BREAKOUT OF CONVECTION. FLOW WILL BE VERY WEAK THROUGH MOST OF THE
CLOUD LAYER AND STORMS WILL BE SLOW MOVING...AND SFC TEMPS SHOULD
SUPPORT SBCAPE OF 1500-2000 J/KG PER BOTH NAM AND GFS PROG SOUNDINGS.
HEAVY RAIN POSSIBLY CAUSING LOCALIZED FLOODING WILL BE A CONCERN...AS
WILL PULSE SEVERE STORM MODES PRIMARILY PRODUCING HAIL DUE TO THE
INSTABILITY. SOUNDINGS ARE ONLY MODESTLY DRY...BUT DCAPE OF 200-700 J
INDICATIVE OF SOME DAMAGING WIND RISK. ACTIVITY SHOULD HAVE
DIFFICULTY ORGANIZING ENOUGH TO PERSIST PAST SUNSET SO POPS AGAIN
DIMINISH TUE NIGHT. HIGHS TUESDAY WILL BE QUITE WARM WITH WEAK SLY
FLOW AT THE SFC AND INITIALLY MOSTLY SUNNY SKIES ALLOWING TEMPS TO
RISE A FEW DEGREES ABOVE NORMAL...INTO THE MID TO UPPER 80S ACROSS
MUCH OF THE AREA.

CONVECTIVE CIRRUS DEBRIS MAY REMAIN OVER MUCH OF THE AREA
OVERNIGHT...WITH INCREASING UPPER MOISTURE AHEAD OF CENTRAL US TROUGH
INTRODUCING MORE HIGH CLOUD COVER TOWARD DAYBREAK AND CONTINUING INTO
WED. THIS SHOULD LIMIT HEATING AND INSTABILITY MAKING TUE OF MORE
INTEREST FOR SIGNIFICANT STORMS...WITH THE ADDITIONAL MID-UPPER
MOISTURE ARRIVING AHEAD OF THE INCOMING TROUGH ALSO MAKING SEVERE
LESS LIKELY. THE TROUGH WORKS INTO THE WEST BY AFTN PERHAPS PROVIDING
SOME ADDITIONAL LIFT. WITH INSTABILITY ALREADY PRESENT THERE HAVE
INCLUDED LIKELY POPS NEAR THE TENN BORDER AND CHC ELSEWHERE...WITH
THE LKLYS WANING WITH THE INSTABILITY TOWARD SUNSET. TEMPS WILL BE A
BIT COOLER WED WITH HIGH CLOUDINESS AND SLIGHTLY LOWER THICKNESSES
HAVING AN IMPACT.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF MIDDAY SUNDAY...GFS/EC HAVE COME INTO BETTER AGREEMENT
REGARDING MID TO LATE WEEK PATTERN. MIDWEST CYCLONE SHIFTS INTO THE
NE CONUS...DRAGGING A COLD FRONT ACROSS THE OH/TN VALLEYS WHICH
WEAKLY PUSHES ACROSS OUR CWFA FRIDAY. ERN TROUGH DEVELOPS AS THE
FRONT PUSHES SOUTH. GFS HAS COME MORE IN LINE WITH THE EC SOLUTION
WHICH WAS ALSO SHOWN ON PREVIOUS RUNS...AND GFS ENSEMBLE MEMBERS ARE
SPREAD SOMEWHAT EVENLY AROUND THE GFS/EC CONSENSUS. MOST OF THE UPPER
ENERGY ASSOCIATED WITH THE MIDWEST SYSTEM REMAINS WELL TO OUR NORTH
THOUGH SOME TRAILING VORT MOVES ACROSS WED NIGHT/THU CONCURRENT WITH
SOME VERY WEAK LLVL WAA.  THIS MAY ALLOW SOME ELEVATED CONVECTION WED
NIGHT...IN FACT THAT IS PROBABLY THE BEST CASE FOR POPS DURING THE
EVENT WITH RELATIVELY DRY COLUMNS SHOWN ON PROG SOUNDINGS. FAIRLY
STEADY POPS CONTINUE UNTIL FROPA FRIDAY. LARGELY DRY FCST FRI NIGHT.

OVER THE WEEKEND POSITION OF SFC HIGH AND UPPER TROUGH ARE INDICATIVE
OF CAD...ESPECIALLY ON THE GFS WHICH ALSO DEVELOPS A WEAK SUBTROPICAL
SYSTEM OFF THE SE COAST ENHANCING THE LLVL ELY FLOW IN THE WEDGE. CAD
LOOKS TO BE LOW IMPACT BEING ACCOMPANIED BY LITTLE MOISTURE.
RESULTING TEMPS ARE NEAR TO JUST BELOW NORMAL FOR THE WEEKEND. SOME
DIURNAL CONVECTION POSSIBLE ON SATURDAY WITH SLIGHTLY UNSTABLE
PROFILES SEEN MAINLY IN THE MTNS...BUT BY SAT NIGHT SUBSIDENCE
INVERSION WILL INHIBIT FURTHER CONVECTION...LEAVING DRY AND MCLR
CONDITIONS FOR SUN.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
AT KCLT...CONVECTION IS EXPANDING IN COVERAGE AND INTENSITY ACROSS
THE PIEDMONT THIS AFTERNOON IN A MODERATELY UNSTABLE AIR MASS. HAVE
BEGUN THE FORECAST WITH A VCSH...BUT INTRODUCED TEMPOS FOR TSRA FROM
19Z THRU 00Z. GUSTY WINDS AND IFR VISBY WILL LIKELY ACCOMPANY TS
THAT MAKE A DIRECT HIT ON THE AIRFIELD...BUT AM UNCERTAIN OF THIS
ATTM. CONVECTION SHOULD GRADUALLY TAPER OFF THIS EVENING...BUT
LOWERING CIGS/POSSIBLY REDUCED VISBY WILL MAKE FOR ADVERSE AVIATION
WEATHER LATE TONIGHT INTO EARLY MONDAY.

ELSEWHERE...CONVECTION WILL BE A LITTLE SLOWER TO DEVELOP AS THE
ATMOSPHERE IS A LITTLE MORE STABLE WEST OF THE NC PIEDMONT.
NEVERTHELESS...CONVECTION MOVING SOUTHEAST OUT OF EAST TENN MAY
RESULT IN NEW CONVECTION DEVELOPING ACROSS WESTERN NC AND UPSTATE SC
BY LATE AFTERNOON/EARLY EVENING. CONVECTION SHOULD GRADUALLY TAPER
OFF THIS EVENING...BUT LOWERING CIGS/POSSIBLY REDUCED VISBY WILL
MAKE FOR ADVERSE AVIATION WEATHER LATE TONIGHT INTO EARLY MONDAY.

OUTLOOK...SCATTERED SHOWERS AND THUNDERSTORMS...AND ASSOCIATED
RESTRICTIONS...ARE EXPECTED TO CONTINUE DURING THE WEEK...BUT SHOULD
BECOME MORE FOCUSED DURING THE AFTERNOON AND EVENING.

CONFIDENCE TABLE...

            19-01Z        01-07Z        07-13Z        13-19Z
KCLT       MED   69%     HIGH  85%     HIGH  86%     MED   78%
KGSP       HIGH  88%     MED   73%     MED   75%     MED   70%
KAVL       HIGH  87%     MED   72%     MED   69%     HIGH  80%
KHKY       HIGH  83%     HIGH  80%     HIGH  97%     MED   70%
KGMU       HIGH  86%     MED   69%     MED   63%     MED   65%
KAND       HIGH  96%     MED   71%     MED   75%     MED   74%

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...JDL
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...JDL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1120 AM EDT SUN MAY 19 2013

GAZ010-017-018-026-028-029-201530-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-
1120 AM EDT SUN MAY 19 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NUMEROUS SHOWERS AND THUNDERSTORMS PRODUCING HEAVY RAINFALL WILL
CONTINUE TO MOVE ACROSS PORTIONS OF NORTH GEORGIA THIS AFTERNOON
AND EVENING. MORE THAN FOUR INCHES OF RAIN FELL EARLY THIS MORNING
ACROSS PORTIONS OF THE NORTHEAST GEORGIA PIEDMONT...AND ANY
ADDITIONAL HEAVY RAINFALL COULD POSE A THREAT FOR FLASH FLOODING.
THIS AREA WILL BE CLOSELY MONITORED FOR A POSSIBLE FLASH FLOOD
WATCH THROUGH EARLY AFTERNOON. IN ADDITION TO THE FLOODING THREAT...A
FEW STORMS MAY BECOME BRIEFLY SEVERE...WITH DAMAGING WINDS AND
LARGE HAIL BEING THE PRIMARY THREAT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

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>059-062>065-068>072-082-501>510-
SCZ001>014-019-201530-
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-
1120 AM EDT SUN MAY 19 2013

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NUMEROUS TO WIDESPREAD SHOWERS AND SCATTERED THUNDERSTORMS WILL
DEVELOP ACROSS THE AREA THIS AFTERNOON. MANY OF THESE SHOWERS AND
STORMS WILL PRODUCE VERY HEAVY RAINFALL. LOCALIZED FLASH FLOODING
WILL BE POSSIBLE IN AREAS THAT SEE REPEATING OR PARTICULARLY SLOW
MOVING THUNDERSTORMS. IN ADDITION...A FEW STORMS MAY BECOME
BRIEFLY SEVERE...WITH DAMAGING WINDS AND LARGE HAIL BEING THE
PRIMARY THREAT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

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.

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
155 PM EDT SUN MAY 19 2013

NCZ052-191845-
HAYWOOD-
155 PM EDT SUN MAY 19 2013

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN HAYWOOD COUNTY THROUGH
245 PM EDT...

AT 148 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR WATERVILLE...OR 17 MILES SOUTH OF NEWPORT...
MOVING EAST AT 15 MPH.

DIME SIZE HAIL...AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS
STORM.

LAT...LON 3580 8297 3575 8296 3574 8292 3562 8285
      3563 8282 3557 8277 3551 8280 3565 8320
      3567 8318 3569 8322 3574 8320 3577 8316
      3580 8308 3578 8299

KRENTZ

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
257 PM EDT SUN MAY 19 2013

NCZ048-191930-
MADISON-
257 PM EDT SUN MAY 19 2013

...A STRONG THUNDERSTORM WILL AFFECT WESTERN MADISON COUNTY THROUGH
330 PM EDT...

AT 256 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 2 MILES NORTHWEST OF HOT SPRINGS...OR 13 MILES
NORTHWEST OF MARSHALL...MOVING SOUTHEAST AT 10 MPH.

* OTHER LOCATIONS AFFECTED INCLUDE BUT ARE NOT LIMITED TO HOT
  SPRINGS.

PENNY SIZE HAIL...AND WIND GUSTS UP TO 50 MPH ARE EXPECTED WITH THIS
STORM.

FREQUENT LIGHTNING IS OCCURRING WITH THIS STORM. IF OUTDOORS...TRY TO
GET INDOORS OR INTO A HARD TOPPED VEHICLE. OTHERWISE...STAY AWAY FROM
OPEN AREAS AND ISOLATED HIGH OBJECTS SUCH AS TREES. WHEN INDOORS...
STAY AWAY FROM WINDOWS AND DOORS AND AVOID USING WIRED ELECTRONIC
DEVICES. TRY TO UNPLUG UNNECESSARY APPLIANCES BEFORE THE STORM
APPROACHES.

LAT...LON 3589 8277 3586 8283 3587 8289 3588 8291
      3591 8292 3593 8292 3596 8288

MCAVOY