Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
452 PM EDT WED AUG 15 2012

.SYNOPSIS...
WEAK HIGH PRESSURE WILL LINGER ATOP THE REGION THROUGH FRIDAY. A
COLD FRONT IS THEN EXPECTED TO MOVE ACROSS THE AREA LATE FRIDAY AND
STALL OUT OVER THE CAROLINAS OVER THE WEEKEND. WEAK HIGH PRESSURE
RETURNS FOR THE FIRST PART OF NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AT 430 PM...WELL DEFINED VORT WILL CONTINUE TO TRIGGER DEEP
CONVECTION INTO THE EARLY EVENING ACRS THE NC PIEDMONT AND SC
UPSTATE. STILL EXPECT CHANCES TO BE EAST OF THE AREA BY 00Z. STILL
CAN NOT RULE OUT AN ISOLATED SVR STORM ACRS THE PIEDMONT
WHERE THE SPC MESOANALYSIS PAGE SHOWS SBCAPES CONTINUING IN THE
2000-2500 J/KG RANGE AND EFFECTIVE BULK SHEAR AROUND 40KTS.
WEAK HIGH PRESSURE WILL BUILD OVER THE AREA LATER THIS EVENING IN
THE WAKE OF THE VORT AND WILL ANTICIPATE GENERALLY CLEAR CONDITIONS
FOR THE OVERNIGHT. LOOKS LIKE MOUNTAIN VALLEY FOG IS A GOOD BET FOR
SEVERAL HOURS LATE TONIGHT INTO EARLY ON THU PER A CONSENSUS OF MOS
GUIDANCE.

PLENTY OF SUNSHINE ON THU WILL PUSH TEMPS TO NEAR OR SLIGHTLY ABOVE
AVERAGE. MODEL SOUNDINGS INDICATE A MID LEVEL WARM NOSE WHICH SHOULD
EFFECTIVELY CAP ANY CONVECTIVE CHANCES FOR THU AFTERNOON. USED A
BLEND OF BIAS CORRECTED MOS FOR THE TEMP FIELDS.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 130 PM EDT WEDNESDAY...THE SHORT TERM FCST PICKS UP AT 00Z ON
FRIDAY WITH A RELATIVELY FLAT UPPER RIDGE OVER THE SE CONUS. HEIGHTS
WILL BEGIN TO FALL AS THE DAY WEARS ON AND BROAD UPPER TROFFING DIGS
DOWN OVER THE EASTERN CONUS. UPPER TROFFING WILL PERSIST THRU
SATURDAY AND INTO THE MEDIUM RANGE AS A STEEP UPPER RIDGE MAINTAINS
ITSELF OVER THE WESTERN CONUS.

ON FRIDAY...EXPECT WEAK S TO SWLY LOW LVL FLOW DURING THE MORNING
AND AFTERNOON. WINDS VEER TO MORE NWLY AS A COLD FRONT APPROACHES
FROM THE OHIO RIVER VALLEY FRIDAY EVENING. THE FRONT IS EXPECTED TO
ESSENTIALLY LAY OVER THE FCST AREA EARLY SAT BUT NOT PUSH VERY FAR TO
THE SE BEFORE WASHING OUT. THE FIRST PART OF FRIDAY SHOULD BE DRY
WITH HIGH TEMPS A FEW DEGREES ABOVE CLIMATOLOGY. POPS RAMP UP RAMP
UP FROM NW TO SE OVER THE CWFA FRI AFTERNOON/EVENING. BY 00Z SAT...I
HAVE LIKELY VALUES OVER THE NC MTS AND PORTIONS OF THE FOOTHILLS
WITH HIGH END SOLID CHANCE ELSEWHERE. EXPECT HEALTHY INSTABILITY AND
LOW TO MID LVL MOISTURE WITH THE FRONTAL APPROACH. LATEST MODEL
SOUNDINGS DO GENERATE SOME BULK SHEAR OVER THE CWFA WITH THE
FROPA...BUT THE MAJORITY IS CONFINED ABOVE 3KM AGL AND IS NOT
PRESENT UNTIL THE LATE NIGHT/OVERNIGHT PERIOD. SO...WE WILL LIKELY
SEE WIDESPREAD CONVECTION DEVELOP LATE FRI INTO SAT OVER THE NW CWFA
WITH SOME MULTICELL TS POSSIBLE. THE TORNADO THREAT IS MINIMAL.

ON SATURDAY...THE FRONT STALLS OUT OVER THE CAROLINAS WITH THE
BERMUDA HIGH STILL LARGELY IN CONTROL OF THE SYNOPTIC PATTERN JUST
TO OUR SOUTH. I MAINTAIN SOLID CHANCE POPS OVER THE CWFA THRU THE
DAY/EVENING AS MOISTURE PROFILES REMAIN FAVORABLE AND THE UPPER TROF
SHOULD PROVIDE SOME SUPPORT FOR LARGE SCALE ASCENT. MAX TEMPS SHOULD
BE ABOUT A CATEGORY LOWER COMPARED TO FRIDAY.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 1140 AM WEDNESDAY...THE MEDIUM RANGE GUIDANCE IS STILL IN GOOD
AGREEMENT THAT A LONG WAVE UPPER TROUGH WILL DEVELOP OVER THE
EASTERN CONUS SUN AND REMAIN IN PLACE THRU TUE. HEIGHTS RISE WED
AS THE TROF AXIS MOVES EAST AND ZONAL FLOW DEVELOPS OVER THE SERN
US. AT THE SURFACE...A FRONTAL BOUNDARY REMAINS STALLED TO OUR SOUTH
AND EAST SUN THRU TUE AS A SERIES OF LOW PRESSURE WAVES MOVE WEST TO
EAST ALONG THE FRONT. THE FRONT MOVES OFFSHORE OR DISSIPATES WED
WITH A MOIST SLY FLOW DEVELOPING OVER THE AREA. THE CANADIAN KEEPS
THE FRONT CLOSER TO OUR CWFA...THE ECMWF IS CLOSER TO THE COAST WITH
THE GFS IN THE MIDDLE. THE CANADIAN ALSO HAS MUCH STRONGER WAVES
MOVING ALONG THE FRONT THAT THE OTHER TWO MODELS. SINCE THE CANADIAN
APPEARS OVERDONE...HAVE TRENDED TOWARD THE GFS/ECMWF WITH A SLIGHT
EDGE TO THE ECMWF. THIS MEANS SCT GENERALLY DIURNAL POP EACH DAY...
WITH HIGHER POP AND LESS OF A DIURNAL TREND SUNDAY WHEN THE FRONT
AND ANY WAVES AND MOISTURE ARE CLOSER TO THE AREA. TUE COULD BE THE
DRIEST DAY WITH THE FRONT AND MOISTURE FARTHER EAST AND SOUTH. WED
WILL SEE A RETURN TO A MORE TYPICAL SCT AFT/EVE TSRA REGIME. TEMPS
WILL BE NEARLY STEADY BELOW NORMAL THRU THE PERIOD.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
AT KCLT...MAIN CONCERN IN THE NEAR TERM IS WHETHER ANY CONVECTION
WILL AFFECT THE AIRFIELD THIS AFTERNOON ASSOCIATED WITH A WEAK COLD
FRONT AND PASSING UPPER WAVE. MESO MODELS CONTINUE TO ADVERTISE SCT
TSRA MOVING NEAR THE AIRFIELD IN THE 18Z-20Z TIMEFRAME...SO WILL
CONTINUE THE TEMPO FOR TSRA FOR THAT PERIOD. OTHERWISE...LIGHT SW
WINDS WILL GRADUALLY SHIFT NW BY 20Z. CLOUDS WILL SCATTERED BY 00Z
BEHIND THE FRONT AND THEN ESSENTIALLY SKC FOR THE REMAINDER OF THE
TAF PERIOD.

ELSEWHERE...SCATTERED CONVECTION ASSOCIATED WITH A WEAK COLD FRONT
AND PASSING UPPER WAVE IS EXPECTED TO AFFECT ONLY THE NC AIRFIELDS.
WIL ADVERTISE A TEMPO AT KHKY 18Z-20Z AND VCTS AT KAVL TIL 19Z.
OTHERWISE...VFR CEILINGS WILL SCT ALL AREAS BY 00Z AND THEN
GENERALLY SKC. MOUNTAIN VALLEY FOG IS EXPECTED LATE TONIGHT
PRODUCIGN A PERIOD OF LIFT AT KAVL IN THE 10Z-13Z TIMEFRAME.
ALSO...A BRIEF PERIOD OF MVFR FOG POSSIBLE AT KAND AND KHKY.

OUTLOOK...HIGH PRESSURE WILL PRODUCE VFR CONDITIONS THROUGH FRIDAY
MORNING. A COLD FRONT WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS
THROUGH AREA FRIDAY AFTERNOON INTO FRI NIGHT. IT APPEARS THE FRONT
WILL LINGER IN THE AREA THROUGH THE WEEKEND WHICH MEANS AT LEAST
SCATTERED SHOWERS AND THUNDERSTORMS EACH DAY...MOST NUMEROUS DURING
THE AFTERNOON AND EVENING HOURS.

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...JPT
NEAR TERM...CSH/LG
SHORT TERM...RWH
LONG TERM...JPT
AVIATION...LG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
410 PM EDT WED AUG 15 2012

NCZ035>037-056-057-068>072-082-502-504-506-508-510-SCZ007>009-013-
014-162015-
ALEXANDER-IREDELL-DAVIE-CATAWBA-ROWAN-CLEVELAND-LINCOLN-GASTON-
MECKLENBURG-CABARRUS-UNION NC-GREATER CALDWELL-GREATER BURKE-
EASTERN MCDOWELL-GREATER RUTHERFORD-EASTERN POLK-SPARTANBURG-
CHEROKEE-YORK-UNION SC-CHESTER-
410 PM EDT WED AUG 15 2012

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

.DAY ONE...TONIGHT.

SCATTERED THUNDERSTORMS WILL MOVE EAST ACROSS THE FOOTHILLS AND
PIEDMONT OF NORTH CAROLINA...AND THE EASTERN UPSTATE OF SOUTH
CAROLINA INTO THE EVENING. A FEW OF THESE STORMS MAY BECOME
SEVERE...PRODUCING LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

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.

GAZ010-017-018-026-028-029-SCZ001>006-010>012-019-162015-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-GREATER OCONEE-
GREATER PICKENS-GREATER GREENVILLE-ANDERSON-ABBEVILLE-LAURENS-
GREENWOOD-
410 PM EDT WED AUG 15 2012

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

.DAY ONE...TONIGHT.

ISOLATED THUNDERSTORMS WILL MOVE SOUTHEAST ACROSS NORTHEAST
GEORGIA AND THE WESTERN UPSTATE OF SOUTH CAROLINA INTO THE
EVENING. THE MAIN THREAT FROM THESE STORMS WILL BE GUSTY WINDS AND
CLOUD TO GROUND LIGHTNING.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

NCZ033-048>053-058-059-062>065-501-503-505-507-509-162015-
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-
CALDWELL MOUNTAINS-BURKE MOUNTAINS-MCDOWELL MOUNTAINS-
RUTHERFORD MOUNTAINS-POLK MOUNTAINS-
410 PM EDT WED AUG 15 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA.

.DAY ONE...TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

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