Damaging Winds in North Carolina, August 10, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
209 PM EDT SAT AUG 10 2013

.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL PERSIST ACROSS THE REGION THROUGH
TUESDAY. A COLD FRONT IS EXPECTED TO MOVE OVER THE REGION LATE
TUESDAY. EXPECT COOLER TEMPERATURES LATE IN THE WEEK AS CANADIAN
HIGH PRESSURE PUSHES THE FRONT TO NEAR THE GULF COAST.

&&

.NEAR TERM /THROUGH SUNDAY/...
AS OF 150 PM EDT...STRONG INSOLATION E OF THE MTNS THIS AFTN HAS
PUSHED SFC BASED CAPE VALUES TO A ROBUST 3000 TO 4500 J/KG GIVEN THE
MID 70S DEWPOINTS IN MOST AREAS. WIDESPREAD COVERAGE HAS ALREADY
TRIGGERED ALONG THE ERN SLOPES OF THE MTNS AND WESTERLY STEERING
FLOW AND OUTFLOWS SHOULD ALLOW THIS TO PROPAGATE EWD THROUGH THE MID
TO LATE AFTN. COVERAGE AND RAINFALL INTENSITY SHOULD REMAIN HIGHEST
ACROSS WRN NC AND THE GA/SC MTNS GIVEN THE ORIENTATION OF THE DEEPER
MOISTURE PLUME EVIDENT ON WATER VAPOR IMAGERY. STILL ANTICIPATE THAT
COVERAGE WILL WANE FAIRLY QUICKLY THIS EVENING WITH THE LOSS OF
DAYTIME HEATING IN SPITE OF THE WEAK SURFACE FRONT DRAPED NORTH OF
THE AREA. ANOTHER ROUND OF MORNING LOW CLOUDS...PATCHY FOG TOWARD
DAYBREAK...AND MIN TEMPS WELL ABOVE NORMAL APPEARS ON TAP FOR SUNDAY
MORNING.

IT NOW APPEARS THAT THE SFC COLD FRONT STRETCHING FROM KY THROUGH VA
THIS AFTN WILL GENERALLY REMAIN N OF THE FORECAST AREA OR WASH OUT
THROUGH SUNDAY. EXPECT MAINLY JUST A SFC TROUGH TO SET UP ACROSS THE
REGION. LOW LEVEL CONVERGENCE SHOULD STILL PROVIDE ENOUGH FORCING
FOR NUMEROUS NW TO SCT SE COVERAGE BY SUN AFTN...WITH THE FOCUS
AGAIN BEING THE MTNS EARLY...THEN ALONG THE PIEDMONT TROUGH AXIS
THROUGH THE AFTN HOURS. THERE WILL CONTINUE TO BE A 0 TO 6 KM SHEAR
GRADIENT FROM HIGHER VALUES ACROSS THE NRN FRINGE NEAR 25 KT...TO
LOWER VALUES NEAR 10 TO 15 KT ACROSS THE FAR S. THIS SUGGESTS THAT
THE BEST POTENTIAL FOR ISOLD SEVERE LATE TODAY AND AGAIN ON SUNDAY
AFTN WILL BE THE NC FOOTHILLS/PIEDMONT. HYDRO CONCERNS WILL CONTINUE
TO BE A PROBLEM JUST ABOUT ANYWHERE TRAINING DEVELOPS...BUT FOCUSED
CONVECTION ALONG THE ERN SLOPS OF THE MTNS WILL PROVIDE THE MOST
AMPLE OPPORTUNITY FOR TRAINING AND ISOLD FLASH FLOODING. WILL
CONTINUE TO CAP MAX TEMPS SUN AFTN BELOW MOST GUIDANCE GIVEN RECENT
PERFORMANCE IN THIS AIRMASS.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AS OF 100 PM EDT SATURDAY...LOOKS TO BE A FAIRLY ACTIVE SHORT RANGE
FORECAST PERIOD ACROSS THE AREA AS BROAD SCALE UPPER TROF PERSISTS.
BY EARLY SUNDAY EVENING...DIURNALLY FORCED CONVECTION WILL LIKELY BE
ONGOING ACROSS MUCH OF THE CWFA.  EXPECTING MUCH OF THIS ACTIVITY TO
PERSIST INTO THE OVERNIGHT HOURS OF MONDAY MORNING AS DAYTIME
HEATING INDUCED INSTABILITY WILL BE SLOW TO DISSIPATE.
FURTHERMORE...WESTERLY UPSLOPE FLOW ALONG THE HIGH TERRAIN WILL AID
IN PERSISTENCE OF SHOWER AND OR THUNDERSTORMS ACTIVITY.

UPPER LVL AND ASSOCIATED SFC RIDGE CENTERED OVER THE WESTERN
ATLANTIC MIGRATES SLIGHTLY TO THE WEST BY MONDAY MORNING.  AS A
RESULT...LOW LEVEL FLOW ACROSS THE SOUTHERN APPALACHIANS WILL SHIFT
TO MORE OF A NORTHWESTERLY COMPONENT DURING THE DAY MONDAY ENHANCING
UPSLOPE LIFT ALONG THE HIGH TERRAIN.  FURTHERMORE...MODELS ARE IN
GOOD AGREEMENT WITH INSTABILITY AXIS REMAINING ACROSS THE EASTERN
ZONES ON MONDAY.  HOWEVER...SOUNDINGS DO INDICATE A FAIR AMOUNT OF
MOISTURE IN THE MID LEVELS INDICATING THAT HEATING COULD BE DAMPENED
SOMEWHAT DUE TO CLOUD COVER.  MENTIONED LIKELY POPS ACROSS THE
MOUNTAINS OF NC IS ASSOCIATION WITH UPSLOPE LIFTING...AND CHANCE
POPS ELSEWHERE DUE TO POSSIBLE DAYTIME HEATING INDUCED CONVECTION.
EXPECTING ACTIVITY TO PERSIST FOR A FEW HOURS BEYOND SUNSET MONDAY
EVENING BEFORE DYING OFF AS THE BOUNDARY LAYER COOLS.

AMPLIFYING UPPER TROF WILL INTERACT WITH EAST/WEST ORIENTED STALLED
FRONTAL BOUNDARY ACROSS KY/VA ON TUESDAY.  THIS BOUNDARY WILL
FINALLY MOVE INTO THE REGION ON TUESDAY AFTERNOON THUS PROVIDING A
FOCUS FOR ENHANCED THUNDERSTORM ACTIVITY.  THERE IS SOME
DISCONTINUITY BETWEEN MODELS WITH RESPECT TO THE AMOUNT OF
INSTABILITY THAT WILL BE PRESENT ACROSS THE REGION ON TUESDAY.  NAM
GUIDANCE WHICH IS NORMALLY THE MOST AGGRESSIVE KEEPS THE AXIS OF
GREATER CAPE ALONG AND EAST OF THE I85 CORRIDOR...WHILE THE GFS
PLACES IT FURTHER TO THE NORTHWEST.  THIS IS LIKELY DUE TO
THE GFS BEING SLIGHTLY SLOWER WITH THE BOUNDARY PROGRESSION INTO THE
REGION WHICH ALLOWS FOR MORE HEATING.  EITHER WAY WOULD NOT BE
SURPRISED TO SEE A FEW STORMS REACH STRONG TO SEVERE LIMITS ON
TUESDAY AS SHEAR INCREASES IN PROXIMITY TO THE FRONT. THUS...CARRIED
LIKELY POPS ACROSS THE ENTIRE REGION INTO TUESDAY EVENING.
TEMPERATURES THROUGH THE PERIOD WILL BE NEAR OR JUST SLIGHTLY BELOW
NORMAL.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 245 AM SATURDAY...EXTENDED RANGE MODELS CONTINUE TO INDICATE
THAT A BROAD AREA OF CANADIAN HIGH PRESSURE WILL BEGIN TO BUILD
SOUTHWARD ACROSS THE GREAT LAKES REGION ON TUESDAY. THE OLD
STATIONARY FRONT WILL BE PICKED UP BY A SECONDARY COLD FRONT...TRACK
SE ACROSS THE CWA TUESDAY AND TUESDAY NIGHT. IN ADDITION...THE MID
LEVEL TROF AXIS IS TIMED TO REACH THE OHIO RIVER VALLEY BY TUESDAY
EVENING. THE TIMING OF THE TROF MAY RESULT IN THE AFTERNOON/EARLY
EVENING PASSAGE OF A WEAK MID S/W OVER THE SOUTHERN APPALACHIANS.
THE COMBINATION OF WEAK TO MARGINAL INSTABILITY...SFC FROPA...AND
MID LEVEL SUPPORT WILL FAVOR AT LEAST NUM MTN TSRA AND SCT/NUM
FOOTHILL AND PIEDMONT TSRA TUES AND TUESDAY NIGHT.

WEDNESDAY THROUGH FRIDAY...THE GFS AND ECMWF INDICATE THAT THE
WESTERN CAROLINAS AND NE GA WILL REMAIN UNDER A MID LEVEL TROF. AT
THE SFC...BOTH SOLUTIONS INDICATE THAT THE COLD FRONT WILL STALL
SOMEWHERE ACROSS THE CENTRAL TO EASTERN CAROLINAS. LLVL ENE WINDS
WILL LIKELY PERSIST WITHIN THE FA THROUGH THE PERIOD. HOWEVER...H85
WINDS ARE FORECAST TO REMAIN FROM THE SE. THIS PATTERN COULD RESULT
IN ABUNDANT CLOUD COVER SUPPORTED BY WEAK LLVL ISENTROPIC LIFT. IN
ADDITION...WEAK INSTABILITY WITH THE REGION OF ISENTROPIC LIFT MAY
YIELD SCT SHRA AND ISO TSRA. THE WEATHER HEADLINE FOR MID TO LATE
NEXT WEEK WILL BE THE DAY TIME TEMPERATURES...FORECAST TO RANGE 6 TO
10 DEGREES BELOW NORMAL.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KCLT...CONVECTIVE COVERAGE IS FILLING IN ALONG A LINE STRETCHING
FROM THE NW PIEDMONT OF NC TO THE UPSTATE SC MOUNTAINS. THE
COMBINATION OF GOOD INSOLATION AND HIGH DEWPOINTS IN THE MID 70S HAS
CREATED STRONG CAPE ACROSS THE REGION...AND TEMPO TSRA AT KCLT SEEMS
A GOOD BET 20Z TO 00Z AS THIS ACTIVITY STEERS EAST. WILL ALSO
ADVERTISE SOME GUSTS TO 30 KT WITH ANY TSRA AS WELL AS BRIEF
RESTRICTIONS. COVERAGE WILL WANE RAPIDLY THIS EVENING...WITH MAINLY
FEW STRATUS/STRATOCUMULUS AROUND ALONG WITH POSSIBLY BRIEF MVFR VSBY
TOWARD DAYBREAK. BRIEF MVFR CIGS WILL BE POSSIBLE WITH HEATING
SUNDAY MORNING...WHILE ANY RENEWED CONVECTION SHOULD HOLD OFF UNTIL
THE AFTN HOURS.

ELSEWHERE...FAIRLY SOLID COVERAGE IS INDICATED ON RADAR ALONG THE
ERN ESCARPMENT OF THE MTNS THIS AFTN...AND THIS ACTIVITY SHOULD
STEER EASTWARD IN ROBUST CAPE VALUES RUNNING 3000 TO 5000 J/KG GIVEN
THE RICH LOW LEVEL DEWPOINTS. ANTICIPATE TEMPO TSRA
THROUGHOUT...WITH BRIEF WIND GUSTS IN THE 20 TO 30 KT RANGE MAINLY
19Z TO 23Z...EXCEPT IMMEDIATELY AT KAVL. ANTICIPATE RESTRICTIONS
WITH ANY TSTMS...POSSIBLY IFR...WITH ADDITIONAL IFR TO MVFR
RESTRICTIONS FORMING OVERNIGHT IN PLACES THAT RECEIVE HEAVY
RAINFALL. THE MOST EXTENDED DAYBREAK IFR CONDITIONS SHOULD AFFECT
KAVL IN THE FRENCH BROAD VALLEY. EXPECT BRIEF MVFR CIGS WITH HEATING
SUNDAY MORNING THEN VFR CIGS BEFORE THE NEXT ROUND OF TSRA GETS
GOING TOWARD THE END OF THE TAF PERIOD.

OUTLOOK...DEEP MOISTURE AND HIGH COVERAGE OF SHRA/TSRA WILL CONTINUE
THROUGH SUNDAY AFTN/EVENING AS A COLD FRONT MOVES SWD TOWARD THE
REGION FROM THE N. THE BOUNDARY MAY LINGER IN THE AREA THROUGH EARLY
NEXT WEEK...YIELDING DIURNAL SCT TO NUMEROUS TSTMS AND OVERNIGHT
RESTRICTIONS.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH  97%     MED   78%
KGSP       HIGH 100%     HIGH 100%     HIGH  97%     MED   78%
KAVL       HIGH  85%     HIGH  97%     MED   75%     HIGH  80%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  85%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   78%
KAND       HIGH 100%     HIGH 100%     HIGH  91%     MED   68%

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...DEO
NEAR TERM...HG
SHORT TERM...CDG
LONG TERM...NED
AVIATION...HG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
535 AM EDT SAT AUG 10 2013

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-110945-
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-
535 AM EDT SAT AUG 10 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 TO NUMEROUS THUNDERSTORMS WILL DEVELOP ACROSS THE
WESTERN CAROLINAS AND NORTHEAST GEORGIA THIS AFTERNOON AND
EVENING. THUNDERSTORM COVERAGE WILL BE THE GREATEST ACROSS THE
NORTH CAROLINA MOUNTAINS AND FOOTHILLS. A COUPLE OF THESE STORMS
MAY PRODUCE FLASH FLOODING AND DAMAGING WIND GUSTS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

SCATTERED TO NUMEROUS THUNDERSTORMS WILL DEVELOP ACROSS THE REGION
AGAIN ON SUNDAY. SEVERAL OF THESE STORMS MAY PRODUCE DAMAGING WIND
GUSTS AND EXCESSIVE RAINFALL.

.SPOTTER INFORMATION STATEMENT...

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

NED

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1110 AM EDT SAT AUG 10 2013

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

0545 PM     TSTM WND DMG     2 S UNION GROVE         35.99N 80.87W
08/09/2013                   IREDELL            NC   EMERGENCY MNGR

            A TWO STORY FARMHOUSE DAMAGED. SEVERAL TREES DOWN AROUND
            THE PROPERTY. TIN BLOWN FROM THE ROOF 1500 FEET ACROSS A
            SOYBEAN FIELD.

&&

OUTLAW

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1148 AM EDT SAT AUG 10 2013

GAZ010-NCZ062-101700-
MACON-RABUN-
1148 AM EDT SAT AUG 10 2013

...A STRONG THUNDERSTORM WILL AFFECT RABUN AND SOUTHERN MACON
COUNTIES THROUGH 100 PM EDT...

AT 1144 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR TITUS...OR 7 MILES EAST OF HIAWASSEE...
MOVING EAST AT 15 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  NACOOHE LAKE...
  LAKE RABUN...
  LAKEMONT...
  CLAYTON...
  MOUNTAIN CITY...
  PINE MOUNTAIN...

WIND GUSTS UP TO 40 MPH...AND TORRENTIAL RAIN 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 3488 8366 3500 8353 3510 8360 3516 8322
      3513 8319 3509 8315 3506 8317 3499 8310
      3494 8311 3488 8324 3482 8327 3482 8331
      3472 8335 3475 8343 3473 8351 3475 8355
      3482 8359 3483 8366

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
137 PM EDT SAT AUG 10 2013

NCZ036-101815-
IREDELL-
137 PM EDT SAT AUG 10 2013

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN IREDELL COUNTY THROUGH
215 PM EDT...

AT 134 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES EAST OF LOVE VALLEY...OR 15 MILES EAST OF
TAYLORSVILLE...MOVING SOUTHEAST AT 20 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  HARMONY...
  HARMONY...

WIND GUSTS UP TO 40 MPH...AND TORRENTIAL RAIN 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 3586 8070 3581 8072 3593 8101 3600 8100
      3603 8102 3606 8101 3606 8069

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
209 PM EDT SAT AUG 10 2013

NCZ504-506-101900-
EASTERN MCDOWELL-GREATER BURKE-
209 PM EDT SAT AUG 10 2013

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN MCDOWELL AND
SOUTHWESTERN BURKE COUNTIES THROUGH 300 PM EDT...

AT 208 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES NORTHEAST OF GLENWOOD...OR 4 MILES
SOUTHEAST OF MARION...MOVING SOUTHEAST AT 5 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  DYSARTSVILLE...

SMALL HAIL...WIND GUSTS UP TO 40 MPH AND TORRENTIAL RAIN ARE EXPECTED
WITH THIS STORM.

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 3569 8172 3558 8180 3558 8182 3554 8185
      3553 8193 3563 8206 3566 8205 3576 8196
      3576 8194