Severe Thunderstorm Warning 17, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1028 PM EDT THU APR 11 2013

.SYNOPSIS...
A STRONG COLD FRONT WILL CROSS THE WESTERN CAROLINAS AND NORTHEAST
GEORGIA TONIGHT. DRY HIGH PRESSURE WILL THEN BUILD IN FROM THE WEST
AND PERSIST THROUGH THE WEEKEND. AN UPPER LEVEL DISTURBANCE WILL
DEVELOP OVER THE GULF COAST SUNDAY AND BRING MOISTURE BACK ACROSS
THE REGION THROUGH THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
0230 UTC UPDATE...THE CURRENT WATCHES ARE STILL IN EFFECT...NO
CHANGES WITH THIS UPDATE. A LINE OF MULTI-CELL/EMBEDDED SUPERCELL
STORMS ARE ENTERING THE SWRN EDGE OF THE CWFA ATTM. SEVERE/TORNADO
THREAT EXISTS WITH THIS LINE AS IT MOVES INTO EXTREME NE GA. A
COUPLE OF CELLS IN THE DOWNSTREAM CONVECTION HAVE BECOME SEVERE. THE
APPROACH OF THE MID/UPR SHORTWAVE SEEMS TO BE FINALLY ERODING THE
MID LVL CAP...AND ALLOWING FOR STRONGER UPDRAFTS...WHILE SHEAR ALSO
IMPROVES. NC MTNS TOR WATCH IN EFFECT TILL 2 AM...THE REST OF THE
AREA TILL 4 AM.

2330 UTC UPDATE...FORGOT TO SEND UPDATED AFD TO ACCOUNT FOR A
TORNADO WATCH FOR ALL OUR NC MTN COUNTIES UNTIL 06Z. A CLUSTER OF
SEVERE TSTMS ARE TRACKING NE ACRS N-CENTRAL GA/SE TN...AND WILL
ENTER THE NC MTNS WITHIN THE NEXT COUPLE HOURS. MEANWHILE...AS
EXPECTED...SCATTERED SHWRS/TSTMS CONTINUE TO INCREASE IN COVERAGE
OUT AHEAD OF THIS ACTIVITY ACRS THE CWFA. SO FAR..A FEW STORMS ACRS
THE MIDLANDS HAVE BEEN REACHING OBJECTIVE SEVERE CRITERIA ON RADAR.
ALSO...WITH THE FRONTAL BAND ENTERING GA...A NEW TORNADO WATCH WILL
BE ISSUED FOR THE REMAINDER OF OUR CWFA THRU 08Z. THE MAIN THREATS
STILL EXPECTED TO BE DAMAGING WINDS AND ISOLATED TORNADOES. WITH
THESE STORMS BEHIND HYBRID SUPERCELLS...LARGE HAIL IS ALSO A THREAT.

2030 UTC UPDATE...DELAYED TIMING OF THE INCREASING POPS FOR THE
REMAINDER OF THE AFTN/EARLY EVENING...PER RADAR TRENDS.
OTHERWISE...FCST LOOKS ON TRACK.

THIS AFTERNOON...SCT CONVECTIVE SHOWERS/STORMS HAVE DEVELOPED OVER
SRN GA AND SC IN WARM MOIST SOUTHERLY FLOW IN WARM SECTOR OF MIDWEST
CYCLONE. THIS ACTIVITY IS NOW BEGINNING TO SPREAD NORTHWARD INTO THE
SRN PORTION OF THE CWFA. CAPPING WARM LAYER ALOFT CURRENTLY SEEMS TO
BE INHIBITING ANY SEVERE WEATHER. AS SFC HEATS FURTHER AND THE CAP
WEAKENS WITH TROUGHING ALOFT...DEEP SFC BASED CONVECTION WILL BE
POSSIBLE. DEEP SHEAR OVER THE CWFA LOOKS TO BE TOO WEAK FOR
SUPERCELLS FOR MOST OF THE AFTERNOON...THOUGH FAVORABLE BRN AND EHI
FOR ROTATING UPDRAFTS WILL BE PRESENT WITH SOME CLOCKWISE TURNING
EVIDENT IN HODOGRAPHS. SEVERE WINDS NOT OUT OF THE QUESTION THOUGH
LARGE HAIL IS LESS OF A THREAT DUE TO THE MODEST INSTABILITY.

DEEP SHEAR INCREASES STEADILY AHEAD OF A COLD FRONT WHICH WILL PUSH
ACROSS THE AREA LATE TONIGHT. THOUGH SFC BASED INSTABILITY WILL WANE
AROUND SUNSET SW WINDS ARE STRONG ENOUGH TO MAINTAIN A LLVL MIXED
LAYER AND ELEVATED INSTABILITY SO THUNDER IS STILL POSSIBLE...AND THE
INCREASING SHEAR WILL MAINTAIN DAMAGING WIND THREAT. NEAR THE
FRONT...LLVL COLD ADVECTION BRINGS THE MIXED LAYER BACK TO THE SFC
AND SFC BASED INSTABILITY RETURNS...ON THE ORDER OF A FEW HUNDRED J
OF CAPE. LENGTHENING AND CURVING HODOGRAPH INDICATES THREAT IS
ESPECIALLY STRONG NEAR THE FRONT. FROPA TIMED SIMILARLY ON GFS/NAM
AND SHOULD ENTER THE WRN ZONES AROUND MIDNIGHT...DEPARTING THE EAST
AROUND DAYBREAK. LINGERING MOISTURE BEHIND THE FRONT SHOULD MAINTAIN
SOME STRATUS/STRATOCU AND PERHAPS SOME SCT SHOWERS BUT THESE WILL
DEPART THE EASTERN ZONES BY MIDDAY.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 115 PM THURSDAY...A RATHER STRAIGHTFORWARD SYNOPTIC PATTERN
DEVELOPS THROUGH THE SHORT TERM. THE MODELS AGREE WELL WITH HEIGHTS
RISING AND THE H5 FLOW TRANSITIONING FROM BROADLY CYCLONIC TO
ANTICYCLONIC THROUGH 00Z MON. THERE WILL BE NO GOOD CHANCE OF PRECIP
THROUGH THE PERIOD AS DEEP LAYERED DRYING MOVES IN FROM THE NW AND
PERSISTS UNTIL UPPER/MID CLOUDS DEVELOP OUT OF THE SW BY MID DAY
SUN. SLIGHT POPS WERE MAINTAINED VERY LATE AROUND 21Z SUN AS
ISENTROPIC LIFT DEVELOPS ALONG WITH INCREASING MOISTURE FLUX. A LOOK
AT BL THETA/E SHOWS FAIRLY WEAK CAA FRI NIGHT...HOWEVER VERY GOOD
INSOLATION AND A DOWNSLOPING COMPONENT WILL OFFSET THE COOLING AND
ALLOW MAX TEMPS A COUPLE DEGREES ABOVE NORMAL. WITH THE INCREASING
UPPER CLOUDS SUN...INSOLATION WILL BE LIMITED YET H100/H85
THICKNESSES INCREASE BY 25 M FROM SAT AFTERNOON VALUES...THUS STILL
EXPECT A CONTINUED INCREASE IN MAXIMUM TEMPS...ABOUT 4-5 DEGREES
ABOVE NORMAL. MIN TEMPS WILL BE RIGHT AROUND NORMAL WITH PERHAPS
ENOUGH COOLING ACROSS THE HIGHER NC MTN TERRAIN TO PRODUCE PATCHY OR
AREAS OF FROST.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 200 PM THU...ALL MEDIUM RANGE MODELS CONTINUE TO FORECAST A
SOUTHERN STREAM WAVE TO MOVE ACROSS THE FORECAST AREA ON MONDAY.
ALSO...ALL THE MODELS SHOW SOME DEGREE OF QPF RESPONSE WITH THIS
FEATURE. THEREFORE...WILL CONTINUE WITH THE IDEA OF FEATURING
SCATTERED TYPE POPS BEGINING LATE SUNDAY NIGHT AND CONTINUING
THROUGH MONDAY. IT APPEARS THAT THE SOUTHERN PORTION OF THE AREA
MIGHT HAVE BETTER COVERAGE AND THIS WILL BE LIKELY BE REFINED WITH
LATER FORECASTS.

AFTER THE WAVE EXITS TO THE EAST MONDAY NIGHT...AN UPPER RIDGE IS
FORECAST TO DEVELOP OVER THE SE STATES AND LINGER THROUGH MIDWEEK. I
LIKE THE ECM DEPICTION OF THE SENSIBLE WEATHER IN THE TUE/WED
TIMEFRAME WHICH DEPICTS ESSENTIALLY DIURNAL TYPE SHOWERS/TSTORMS
WHICH FITS THE CONCEPTUAL MODEL OF THE EXPECTED WEATHER PATTERN.
HENCE WILL FORECAST SCATTERED AFTERNOON SHOWERS/TSTORMS...BUT KEEP
THEM CONFINED TO THE MOUNTAINS. ON THU...A COLD FRONT WILL APPROACH
FROM THE WEST AND PERHAPS MOVE THROUGH THE AREA BY LATE IN THE DAY
PER THE GFS. THE ECM IS SLOWER AND HPC HAS TAKEN A COMPROMISE
SOLUTION WHICH STILL RAMPS UP CHANCE POPS ACROSS THE AREA ON THU.
TEMPERATURES WILL BE NEAR SEASONAL LEVELS ON MONDAY AND THEN WARM TO
WELL ABOVE NORMAL ON TUE/WED AND THEN BACK TO NEAR NORMAL FOR THU
DUE TO CLOUDS AND PRECIP.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
AT KCLT...NO MAJOR CHANGES TO THE TAF FOR 00Z. STILL LOOKS LIKE TWO
ROUNDS OF SHOWERS/THUNDERSTORMS TO AFFECT THE FIELD DURING THE
PERIOD. THE FIRST BATCH IS EXPANDING IN COVERAGE ACRS CENTRAL SC
ATTM...AND LIFTING NWD. THIS ACTIVITY WILL AFFECT CLT IN THE 01-04Z
TIME FRAME...AND BE SCATTERED IN NATURE (SO WILL KEEP JUST A TEMPO
FOR TS). THE SECOND ROUND OF STORMS WILL BE ASSOCIATED WITH A COLD
FROPA PROVIDING STRONG FORCING IN THE 04-09Z TIME FRAME. WILL GO
PREVAILING TSRA FOR THIS ACTIVITY...AS IT SHOULD BE MORE SOLID IN
COVERAGE. TRAILING STRATIFORM RAIN/EMBEDDED TS WILL LIKELY LINGER
THRU ABOUT 12Z. IFR/MVFR CIGS SHUD GRADUALLY IMPROVE FRI
MORNING...AS DRY W/NWLY FLOW WILL FILTER IN BEHIND THE FRONT. THE
SFC WINDS WILL STAY SWLY AND BECOME SOMEWHAT GUSTY AS SKIES CLEAR
FRIDAY AFTN.

ELSEWHERE...SCATTERED SHRA/TSRA ARE INCREASING IN COVERAGE THIS
EVENING ACRS THE REGION...BUT HAVE REMAINED GARDEN VARIETY SO FAR.
WILL HANDLE THIS ACTIVITY WITH TEMPO GROUPS FOR THE NEXT 2-4 HOURS.
THERE MAY BE BRIEF LULL IN ACTIVITY...ESP IN THE UPSTATE BEFORE A
MORE SOLID LINE OF TSRA CROSSES THE AREA FROM WEST TO EAST IN THE
03-08Z TIME FRAME. WILL GO WITH PREVAILING TSRA AT ALL SITES.
TRAILING STRATIFORM RAIN/EMBEDDED TS WILL LINGER DURING PRE-DAWN
HOURS...THEN CLEAR OUT BY DAYBREAK. STRATUS SHUD IMPROVE FRIDAY
MORNING...AS DRY AIR FILTERS IN BEHIND THE FRONT. VFR CONDITIONS
WITH SOMEWHAT GUSTY SW WINDS (NW AT KAVL) EXPECTED FRIDAY AFTN.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD INTO THE REGION THROUGH THE
WEEKEND.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-02Z
KCLT       MED   62%     MED   69%     HIGH  95%     HIGH 100%
KGSP       MED   62%     MED   75%     HIGH 100%     HIGH 100%
KAVL       MED   63%     MED   76%     HIGH  94%     HIGH 100%
KHKY       MED   66%     MED   66%     HIGH  98%     HIGH 100%
KGMU       MED   60%     MED   73%     HIGH 100%     HIGH 100%
KAND       LOW   58%     MED   77%     HIGH  96%     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...LG
AVIATION...ARK

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
832 PM EDT THU APR 11 2013

GAZ010-017-018-026-028-029-NCZ035>037-056-057-068>072-082-501>510-
SCZ001>014-019-130045-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-ALEXANDER-IREDELL-
DAVIE-CATAWBA-ROWAN-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-
832 PM EDT THU APR 11 2013

...TORNADO WATCH 101 IN EFFECT UNTIL 4 AM EDT FRIDAY...

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

.DAY ONE...TONIGHT.

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

   TORNADO WATCH.

.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...TORNADOES OR FLASH FLOODING TO OUR OFFICE.

NCZ033-048>053-058-059-062>065-130045-
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-
832 PM EDT THU APR 11 2013

...TORNADO WATCH 100 IN EFFECT UNTIL 2 AM EDT FRIDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA.

.DAY ONE...TONIGHT.

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

   TORNADO WATCH.

.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...TORNADOES OR FLASH FLOODING TO OUR OFFICE.

ARK

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1006 PM EDT THU APR 11 2013

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

0958 PM     TSTM WND DMG     MAIDEN                  35.58N 81.21W
04/11/2013                   CATAWBA            NC   TRAINED SPOTTER

            REPORTS OF TREES DOWN NEAR MAIDEN

&&

MOORE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1046 PM EDT THU APR 11 2013

GAZ010-NCZ062-063-120330-
MACON-RABUN-SOUTHERN JACKSON-
1046 PM EDT THU APR 11 2013

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN RABUN...
SOUTHEASTERN MACON AND SOUTHERN JACKSON COUNTIES THROUGH 1130 PM
EDT...

AT 1043 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES SOUTH OF SKY VALLEY...OR 6 MILES
NORTHEAST OF CLAYTON...MOVING NORTHEAST AT 25 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  PINE MOUNTAIN...
  HIGHLANDS...
  CASHIERS...

INTENSE LIGHTNING AND WIND GUSTS OF 40 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.

PLEASE REPORT DAMAGING WINDS...HAIL...OR FLOODING TO THE NATIONAL
WEATHER SERVICE GREENVILLE SPARTANBURG BY CALLING TOLL FREE...1...
800...2 6 7...8 1 0 1...OR BY POSTING ON OUR FACEBOOK PAGE...OR TWEET
IT USING HASHTAG NWSGSP. YOUR MESSAGE SHOULD DESCRIBE THE EVENT AND
SPECIFIC LOCATION WHERE IT OCCURRED.

LAT...LON 3523 8322 3525 8314 3510 8302 3507 8305
      3505 8305 3503 8301 3500 8310 3499 8310
      3496 8312 3483 8336 3497 8346

LANE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1051 PM EDT THU APR 11 2013

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

1004 PM     TSTM WND DMG     6 WSW STATESVILLE       35.75N 80.99W
04/11/2013                   IREDELL            NC   911 CALL CENTER

            TREES DOWN NEAR THE INTERSECTION OF OLD MOUNTAIN ROAD AND
            US HIGHWAY 70.

&&

MOORE