Hail and Damaging Wind in North Carolina, August 23, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
229 PM EDT FRI AUG 23 2013

.SYNOPSIS...
A COLD FRONT WILL MOVE INTO THE REGION TONIGHT...TRIGGERING SHOWERS
AND THUNDERSTORMS BEFORE USHERING IN DRIER WEATHER FOR THE WEEKEND.
HIGH PRESSURE WILL BUILD BACK IN FOR THE FIRST PART OF THE
WEEK...BEGINNING A GRADUAL WARMING TREND. RETURNING SOUTHERLY FLOW
WILL GRADUALLY INCREASE MOISTURE ACROSS THE REGION...INCREASING
CHANCES FOR SHOWERS AND THUNDERSTORMS EACH AFTERNOON. A SERIES OF
COLD FRONTS WILL MOVE THROUGH THE REGION LATE IN THE WEEK ELEVATING
RAIN CHANCES FURTHER.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 230 PM EDT FRIDAY...A LINE OF SHOWERS AND THUNDERSTORMS HAS
DEVELOPED OVER THE WRN NC FOOTHILLS AND PIEDMONT. THE LINE IS BEING
FORCED BY LLVL SFC CONVERGENCE AND DIFFERENTIAL HEATING RESULTING
FROM THE APPROACH OF AN H5 SHORT WAVE WHICH THE RAP CURRENTLY HAS
LOCATED OVER NE TN AND SW VA. THE DEEP LAYER SHEAR ISN/T
STRONG...BUT THE AIRMASS AHEAD OF THE LINE IS QUITE UNSTABLE AND IT
ALREADY HAS A WELL ESTABLISHED REAR INFLOW JET PER THE TERMINAL
DOPPLER RADAR AT CHARLOTTE. THE NAM AND GFS BOTH STRENGTHEN SFC
CONVERGENCE AHEAD OF THE LINE. THEREFORE IT SHOULD CONTINUE TO MOVE
TO THE SOUTHEAST AND AT LEAST MAINTAIN ITSELF IF NOT GET STRONGER.
BUT IT SHOULD ALSO BUILD TO THE SOUTHWEST...OR NEW STORMS MAY
ORIGINATE OVER THE SC MTNS...AS THE LLVL WINDS BACK ACROSS MOST OF
THE UPSTATE AND EVEN INTO NE GA OVER THE NEXT COUPLE HOURS. AT THIS
RATE MOST LOCATIONS OVER THE FOOTHILLS AND PIEDMONT SHOULD GET INTO
THE ACT OVER THE NEXT 4 TO 6 HOURS AND POPS HAVE BEEN RAISED TO
LIKELY TO CATEGORICAL FOR THE REST OF THE DAY. DCAPE VALUES ARE HIGH
OVER THE UPSTATE...BUT DROP OFF RAPIDLY INTO NORTH CAROLINA. SO AS
THE LINE MOVE SOUTHWARD...IT/S TENDENCY TO PRODUCE STRONG OUTFLOW
SHOULD INCREASE.

STORMS SHOULD DIMINISH FROM NORTH TO SOUTH THIS EVENING. I THINK
THERE WILL ENOUGH CONVECTIVE DEBRIS AND MIXING EAST OF THE MTNS TO
PREVENT FOG FROM FORMING AGAIN. OVER THE MOUNTAINS WINDS ARE
EXPECTED TO DECOUPLE OVERNIGHT AS THE LLVL GRADIENT WINDS WILL BE
ORIENTED OUT OF THE NE...ORTHOGONAL TO THE HIGHER NC MTN CHAINS.
THEREFORE...THE MTN VALLEYS SHOULD SEE FOG AND STRATUS ONCE AGAIN.

COLD AIR DAMMING DEVELOPS FOR SATURDAY. THE MODELS STILL HAVE
1000-2000 SBCAPE VALUES OVER THE SOUTHERN ZONES. I/VE KEPT LOW END
CHANCE POPS ALONG THE UPPER SAVANNAH RIVER VALLEY AND OVER THE
SOUTHWEST AND CENTRAL NC MTNS. TYPICALLY IN THESE SITUATIONS MOST OF
THE DEVELOPMENT IS OVER THE SW MTNS AND ALONG THE EASTERN ESCARPMENT
OF THE BLUE RIDGE. CLOUDS MAY DISSIPATE IN THE DRIER AIR OVER THE
PIEDMONT AND ALONG THE TN LINE...WITH GENERALLY MOSTLY CLOUDY SKIES
EXPECTED ELSEWHERE.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AT 230 PM EDT FRIDAY...A STRONG UPPER HIGH WILL BE CENTERED OVER MO
ON SATURDAY NIGHT....WHILE A POSITIVELY TILTED UPPER TROUGH WILL BE
JUST OFF THE EAST COAST. THIS TROUGH MOVES FARTHER OFF THE EAST
COAST ON SUNDAY...WHILE THE UPPER RIDGE REMAINS CENTERED OVER MO. ON
MONDAY THE UPPER RIDGE RETROGRESSES INTO KS.

A COLD FRONT TO OUR SOUTH WILL DRIFT FARTHER SOUTH ACROSS FL
SATURDAY NIGHT AND SUNDAY...WHILE DRIER AIR AND HIGH PRESSURE SPREAD
ACROSS THE CAROLINAS AND GA FROM THE NE. MODEL TIME HEIGHTS SHOW A
THINNING...LINGERING LAYER OF MOISTURE AT AROUND 850 MB BEHIND THE
FRONT. WITH JUST A WEAK EASTERLY UPSLOPE FLOW DEVELOPING AS WIDNS
VEER IN THE LOW LEVELS...ONLY VERY SMALL POPS WILL BE CARRIED LATE
MONDAY. TEMPERATURES WILL RUN BELOW NORMAL THROUGH THE PERIOD...WITH
A SLIGHT WARMING TREND ON MONDAY AS HEIGHTS RISE ALOFT WITH THE
PROGRESSION OF THE ATLANTIC TROUGH.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 200 PM EDT FRIDAY...OVERALL A MUCH DRIER PATTERN FOR THE
EXTENDED THAN WHAT WE HAVE SEEN IN THE PAST FEW WEEKS. AN UPPER
RIDGE WILL BE FIRMLY ENTRENCHED OVER THE CENTRAL PLAINS BY MONDAY
NIGHT WHILE A SURFACE RIDGE WILL SHIFT SOUTHEASTWARD TOWARDS THE
ATLANTIC TO TAKE ON BERMUDA HIGH CHARACTERISTICS. THIS WILL SET UP A
WEAK SOUTHEASTERLY FLOW REGIME AT THE SURFACE...AND BY WEDNESDAY A
HIGH IN THE NORTHEAST WILL ALLOW A WEAK WEDGE TO BUILD IN OVER THE
APPALACHIANS AND ADVECT IN MODERATELY DRIER AIR. ANY CONVECTION WILL
FOLLOW A DIURNAL PATTERN...AND THEN WILL BE LIMITED MAINLY TO AREAS
OF UPSLOPE FLOW. AN EXPANDING SURFACE HIGH OVER THE GREAT LAKES WILL
PUSH MULTIPLE FRONTAL BOUNDARIES SOUTHWARD THROUGH THE CWA BY THE
END OF THE WEEK...INCREASING RAIN CHANCES ONCE AGAIN. RISING HEIGHTS
DUE TO THE UPPER LEVEL RIDGE WILL ALLOW HIGH TEMPERATURES TO
MODERATE BACK TO NORMAL LEVELS...IN THE MID TO HIGH 80S...FOR MOST
OF NEXT WEEK.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...A LINE OF THUNDERSTORMS IS ORGANIZING 40 TO 50 MILES
NORTHWEST OF THE AIRFIELD. IT SHOULD CONTINUE MOVING SOUTHEAST AND
WILL LIKELY ACCELERATE A LITTLE AS IT DOES. TEMPO THUNDER HAS BEEN
MOVED UP AN HOUR...FROM 19-22 UTC. STORMS ARE SHOWING 30-35KT
INBOUNDS ON TDWR. THE LINE SHOULD STRENGTHEN SOME AS IT APPROACHES
AND I/VE ADDED A PERIOD OF 35 KT GUSTS TO THE TAF. I WENT
VARIABLE...THOUGH THE STRONGEST WINDS ARE LIKELY TO BE ORIENTED OUT
OF THE NORTH. SCT SHRA AND A FEW TSTMS WILL PERSIST INTO THE LATE
EVENING HOURS. LATER TONIGHT AN MVFR STRATO-CU DECK MAY MOVE IN AS
THE TRUE SFC OLD FRONT ARRIVES. THE RAP AND OUR LOCAL WRF ARW DO
THIS AND I/VE ADDED A PERIOD OF MVFR CIGS FROM 09-14 UTC TONIGHT AND
TWRW. WINDS WILL VEER FROM NW TO NE AS THE FRONT MOVES THROUGH.

ELSEWHERE...A LINE OF THUNDERSTORMS WILL DROP SOUTHEAST ACROSS THE
NC AND SC PIEDMONT THIS AFTERNOON AND EVENING. THE QUESTION IS HOW
FAR TO THE SOUTHWEST THE LINE WILL BUILD. THE MODELS HAVE GOOD
CONVERGENCE WELL INTO THE UPSTATE...SO I THINK THE LINE WILL BUILD
TO THE SOUTHWEST AND I/VE ADDED TEMPO THUNDER IN AT KGMU/KGSP
STARTING AT 20 UTC. THE LINE IS PRACTICALLY ON TOP OF HKY AND THEY
HAVE A TEMPO FOR THE NEXT COUPLE HOURS. I/M NOT AS CONFIDENT OF KAND
AND TEMPO WAS LEFT OUT OF THAT SITE. KAVL WILL PROBABLY SEE
SOMETHING SO THEY GOT A TEMPO AS WELL. LATER TONIGHT MVFR CIGS WILL
DEVELOP OVER NC...BUT THEY MAY NOT MAKE IT INTO THE UPSTATE.
THEREFORE NO MVFR CIGS WERE CARRIED AT THE SOUTH CAROLINA TAF SITES.
AT KAVL THE WINDS SHOULD BE COME LIGHT LATE TONIGHT AS THE FRONT IS
MOVING IN FROM THE NE. THIS WILL SUPPORT ANOTHER NIGHT WITH STRATUS
AND FOG. WINDS WILL BECOME RATHER BRISK OUT OF THE NORTHEAST AFTER
SUNRISE. I WOULDN/T BE SURPRISED TO SEE SOME GUSTS UP TO 20 KTS OVER
THE UPSTATE AND AT KCLT.

OUTLOOK...A DRIER PATTERN IS EXPECTED AS HIGH PRESSURE GRADUALLY
BUILDS IN FROM THE NORTH OVER THE WEEKEND.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH  85%     HIGH  85%
KGSP       HIGH 100%     HIGH 100%     HIGH  80%     HIGH  97%
KAVL       HIGH 100%     MED   77%     LOW   51%     LOW   56%
KHKY       HIGH 100%     HIGH  94%     LOW   42%     HIGH  81%
KGMU       HIGH 100%     HIGH 100%     HIGH  83%     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...VISIN
NEAR TERM...MCAVOY
SHORT TERM...JAT
LONG TERM...VISIN
AVIATION...MCAVOY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
229 AM EDT FRI AUG 23 2013

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-240630-
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-
229 AM EDT FRI AUG 23 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 COLD FRONT WILL PUSH INTO THE AREA FROM THE NORTH THIS AFTERNOON
INTO TONIGHT. SCATTERED THUNDERSTORMS ARE EXPECTED ALONG AND AHEAD
OF THE FRONT...WITH A FEW POSSIBLY PRODUCING LARGE HAIL AND
DAMAGING WIND GUSTS. ISOLATED FLASH FLOODING WILL BE POSSIBLE WITH
SOME OF THE HEAVIER DOWNPOURS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

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.

CDG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
134 PM EDT FRI AUG 23 2013

NCZ035-036-056-057-231815-
ALEXANDER-CATAWBA-IREDELL-ROWAN-
134 PM EDT FRI AUG 23 2013

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL IREDELL...EASTERN
CATAWBA...NORTHWESTERN ROWAN AND SOUTHERN ALEXANDER COUNTIES THROUGH
215 PM EDT...

AT 132 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR SCOTTS...OR 8 MILES NORTHWEST OF
STATESVILLE...MOVING SOUTHEAST AT 10 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  LOOKOUT SHOALS LAKE...
  CLAREMONT...
  NEWTON...
  STATESVILLE...
  TROUTMAN...

WIND GUSTS UP TO 40 MPH...AND TORRENTIAL RAINFALL 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 3569 8061 3555 8101 3555 8115 3584 8132
      3587 8108 3594 8077

JPT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
217 PM EDT FRI AUG 23 2013

NCZ036-056-057-069>072-231900-
CABARRUS-CATAWBA-GASTON-IREDELL-LINCOLN-MECKLENBURG-ROWAN-
217 PM EDT FRI AUG 23 2013

...A STRONG THUNDERSTORM WILL AFFECT EASTERN LINCOLN...NORTHEASTERN
GASTON...NORTHERN MECKLENBURG...NORTHWESTERN CABARRUS...SOUTHERN
CATAWBA...SOUTHERN IREDELL AND WESTERN ROWAN COUNTIES THROUGH 300 PM
EDT...

AT 216 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES NORTHEAST OF TERRELL...OR 12 MILES SOUTH
OF STATESVILLE...MOVING SOUTHEAST AT 20 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  DENVER...
  LAKE NORMAN...
  MOORESVILLE...
  DAVIDSON...
  CORNELIUS...
  CHINA GROVE...

WIND GUSTS UP TO 40 MPH...AND TORRENTIAL RAINFALL 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 3546 8044 3530 8072 3526 8110 3566 8135
      3563 8108 3569 8081 3574 8061

JPT