Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1034 AM EDT THU AUG 9 2012

.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM WILL DEVELOP OVER THE GREAT LAKES TODAY
THROUGH FRIDAY. THE SYSTEM WILL PUSH A COLD FRONT ACROSS THE REGION
FROM THE WEST LATE FRIDAY. THE FRONT WILL PUSH SOUTH OF THE AREA
LATE SATURDAY...FOLLOWED BY DRY HIGH PRESSURE FOR SUNDAY INTO EARLY
NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM EDT...HIGH LEVEL CLOUDINESS HAS BEEN RATHER ABUNDANT
ACROSS THE REGION THIS MORNING AHEAD OF AN UPPER LEVEL SHORTWAVE
ACROSS TN. MAX TEMPS HAVE BEEN TRIMMED ABOUT A DEGREE MOST AREAS DUE
TO THE REDUCED INSOLATION. THE LIMITED SUNSHINE HAS ALSO HAD AN
IMPACT ON THE INSTABILITY...WITH CONVECTIVE INITIATION LIKELY A BIT
SLOWER TO START THAN YESTERDAY. STILL ANTICIPATE SCATTERED
TRIGGERING ALONG THE SRN/ERN MTN ESCARPMENTS AND ALONG THE RIDGES
BETWEEN NOON AND 2 PM...WITH ADDITIONAL ISOLD CELLS FORMING IN LOW
LEVEL MOIST SW FLOW FROM GA. COVERAGE SHOULD TAKE A BIT MORE TIME TO
RAMP UP ON OUTFLOWS ACROSS THE REST OF THE FOOTHILLS AND PIEDMONT
THROUGH LATE AFTN/EVENING. SOUNDINGS CONTINUE TO EXHIBIT 30+ K THETA
E LAPSES AND A FEW SEVERE MICROBURSTS OR LARGE HAIL REPORTS WILL BE
POSSIBLE LATER TODAY. GIVEN THE CONTINUED/IMPROVING WARM ADVECTION
FLOW AND MOISTURE TONIGHT...WILL NEED TO RETAIN ISOLD TO CHC POPS
INTO THE EARLY MORNING HOURS FRIDAY.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 315 AM THURSDAY...MODELS IN BETTER AGREEMENT ON THEIR HANDLING
OF THE DEVELOPING CYCLONE OVR THE GREAT LAKES. THE 00Z NAM IS JUST A
HAIR SLOWER WITH THE SYSTEM AND THE ASSOCIATED COLD FRONT. THE HPC
PREFERENCE IS THE NON-NAM CONSENSUS...WHICH ALLOWS FOR A NARROWING
OF THE WINDOW OF POPS WITH THE FRONT SLIGHTLY. THE STRONGEST FORCING
WILL REMAIN OVR THE GREAT LAKES...AND THE MODELS STILL SHOW MODEST
INSTBY AT BEST WITH RATHER WEAK SHEAR. SO KEEPING POPS AT LIKELY.
THE SEVERE THREAT STILL UNCERTAIN GIVEN THE FCST SNDGS. STILL THINK
THERE WILL BE SOME SORT OF LINE OF CONVECTION ALONG THE FRONT WHICH
MAY BE SEVERE IF THERE IS ENUF DESTABILIZATION AHEAD OF IT.

FRIDAY NIGHT AND SATURDAY...WITH THE UPPER LOW SPINNING NORTH OF THE
REGION...AND ANOTHER SHORT WAVE TROUGH DROPPING OUT OF THE PLAINS...
THE MID-LEVEL TROUGH AXIS/SURFACE FRONT TAKES ITS TIME PUSHING
THROUGH THE AREA. IN FACT...BOTH MODELS FEATURE QUITE A BIT OF QPF
ACROSS THE SOUTHEAST HALF OF THE FORECAST AREA AFTER 12Z SATURDAY.
SO SOLID CHC POPS ALONG AND SOUTH OF I-85 STILL LOOKS GOOD.
HOWEVER...MODELS SHOW LITTLE RESPONSE IN THE HIGH TERRAIN WHERE
SUBSIDENCE BEHIND THE TROF AXIS STRENGTHENS. SO CUT POPS BACK IN THE
MTNS. TEMPS WILL BE BELOW NORMAL BOTH DAYS...WITH LOWS NEAR NORMAL
FRIDAY NIGHT BUT NOTICEABLY COOLER (AND DRIER) SATURDAY NIGHT.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 330 AM THURSDAY...AS LOW PRESSURE SYSTEM OCCLUDES AND BEGINS
TO LIFT NORTH OVR THE GREAT LAKES INTO SRN ONT...STRONG HEIGHT RISES
DEVELOP OVR THE CWFA FOR SUNDAY. THE GFS FCST SNDGS SHOW STRONG
SUBSIDENCE INVERSION OVR THE HIGH TERRAIN. SO TWEAKED POPS SUCH THAT
SUNDAY IS A DRY DAY. TEMPS WILL REMAIN ABOUT A CATEGORY BELOW NORMAL
TO NORMAL. FROM MONDAY THRU WEDNESDAY...UPR FLOW FLATTENS OUT TO
QUASI-ZONAL...WITH WEAK TROFINESS LINGERING OVR THE ERN CONUS. BOTH
THE 00Z GFS AND ECMWF SHOW A WEAK...RELATIVELY DRY COLD FRONT
PASSAGE ON TUESDAY...THEN DRY NWLY FLOW FOR WEDNESDAY. TEMPS
REMAIN NEAR NORMAL WITH RELATIVELY LOW POPS.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
AT KCLT...BROKEN HIGH LEVEL CLOUDS ARE LIMITING THE INCREASE IN
INSTABIILTY AROUND THE KCLT VICINITY LATE THIS MORNING. STILL
ANTICIPATE SOME CONVECTIVE DEVELOPMENT FROM THE SW AS MOISTURE
SLOWLY INCREASES ACROSS THE REGION. WITH THE 15Z UPDATE...WILL
FEATURE TEMPO TSRA STARTING 21Z...SINCE ACTIVITY SHOULD ARRIVE A BIT
LATER THAN YESTERDAY. MID TO HIGH LEVEL DEBRIS CLOUDS SHOULD LINGER
INTO THE NIGHT RESULTING IN ONLY LIMITED CHANCES OF VSBY
RESTRICTIONS FOR FRIDAY MORNING.

ELSEWHERE...LINGERING IFR SHOULD SLOWLY LIFT AND SCATTER AT KAVL AND
KAND THIS MORNING. ALL THE MESOSCALE MODELS FEATURE SOME DEGREE OF
SCATTERED CONVECTION FORMING ALONG THE ERN ESCARPMENT OF THE MTNS OR
ARRIVING FROM THE SW IN INCREASINGLY MOIST FLOW EARLY THIS AFTN.
CONFIDENCE REMAINS HIGHEST FOR TSRA AT KAVL...WITH A TEMPO GROUP
FEATURED FROM 18Z TO 22Z. WILL RETAIN VCTS MENTION AT THE OTHER TAF
SITES WHERE CONFIDENCE IS LOWER AS INSTABILITY IS SLOW TO INCREASE
UNDER HIGH LEVEL CLOUDINESS. MID AND HIGH CLOUDS FROM EVENING
CONVECTIVE DEBRIS AND AHEAD OF THE UPSTREAM TROUGH WILL PERSIST
OVERNIGHT FOR ALL LOCATIONS. RESTRICTIONS WILL DEVELOP AGAIN AT
KAVL.

OUTLOOK...A COLD FRONT WILL APPROACH FROM THE NW ON FRIDAY TO
INCREASE THUNDERSTORM COVERAGE THROUGH FRI NIGHT. DRIER HIGH PRES
WILL RETURN OVER THE WEEKEND AND LINGER INTO EARLY NEXT WEEK.

AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...

WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

SYNOPSIS...ARK
NEAR TERM...HG
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...HG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
510 AM EDT THU AUG 9 2012

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-100915-
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-
510 AM EDT THU AUG 9 2012

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

.DAY ONE...TODAY AND TONIGHT.

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THE REGION
THIS AFTERNOON AND EVENING. SOME OF THE STORMS WILL BE CAPABLE OF
PRODUCING LOCALLY DAMAGING WIND GUSTS AND LARGE HAIL.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

A STRONG COLD FRONT WILL APPROACH THE REGION LATE FRIDAY. THERE
IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ASSOCIATED WITH THE
FRONT. DAMAGING WIND GUSTS WILL BE THE PRIMARY THREAT.

.SPOTTER INFORMATION STATEMENT...

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
139 PM EDT THU AUG 9 2012

NCZ051-058-091830-
GRAHAM-SWAIN-
139 PM EDT THU AUG 9 2012

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN GRAHAM AND WESTERN
SWAIN COUNTIES THROUGH 230 PM EDT...

AT 135 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR TAPOCO...OR 11 MILES NORTHWEST OF
ROBBINSVILLE...MOVING NORTHEAST AT 10 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  FONTANA VILLAGE...

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

LAT...LON 3542 8401 3545 8399 3548 8392 3553 8388
      3553 8383 3554 8380 3555 8379 3547 8371
      3535 8394 3541 8403

LANE