Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
255 PM EDT WED JUL 18 2012

.SYNOPSIS...
HIGH PRESSURE WILL WEAKEN AND SHIFT SOUTH OVER THE NEXT FEW DAYS.
THIS WILL ALLOW A FRONTAL BOUNDARY OVER THE OHIO VALLEY TO DROP
SOUTH...INTO THE CAROLINAS LATE FRIDAY. THE FRONT WILL REMAIN
OVER OR JUST SOUTH OF THE REGION THROUGH THE WEEKEND AND DISSIPATE
ON MONDAY.

&&

.NEAR TERM /THROUGH THURSDAY/...
AT 230 PM EDT WEDNESDAY...THE WEAK UPPER LOW OVER GA WILL LIFT NORTH
AND FILL OVER SC TONIGHT AND FRIDAY...WHILE A TROUGH TO THE NORTH
AMPLIFIES. CONVECTION DEVELOPING THIS AFTERNOON IS EXPECTED TO
INCREASE IN COVERAGE...THEN GRADUALLY DIMINISH THIS EVENING AS
HEATING ABATES. MODELS SOUNDINGS ARE SUPPORTIVE OF GUSTY WINDS A ND
HAIL...WITH SLOW MOVING STORMS PRODUCING LOCALLY HEAVY RAINFALL.
MINIMUM TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL IN A MOIST AIR
MASS.

IMPULSES MOVING THROUGH THE BASE DO THE AMPLIFYING TROUGH ON
THURSDAY WILL SUPPORT GREATER POPS THAN IN PREVIOUS DAYS. ACTIVITY
IS EXPECTED TO GET GOING EARLIER THAN USUAL IN THE MOUNTAINS...WITH
SUBSTANTIAL COVERAGE BY MIDDAY. ONCE AGAIN... MODEL SOUNDINGS ARE
SUPPORTIVE OF PULSE SEVERE THUNDERSTORMS...AND LIGHT STEERING
CURRENTS WILL SUPPORT HEAVY RAINFALL ACCUMULATIONS. A COLD FRONT
APPROACHING FORM THE NORTH WILL STILL BE IN VA...TOO FAR AWAY TO
HAVE AN IMPACT THROUGH THURSDAY AFTERNOON. MAXIMUM TEMPERATURES WILL
BE ABOVE NORMAL AS TROUGH AMPLIFICATION AND FALLING HEIGHTS ALOFT
TAKE PLACE LATER IN THE DAY. THE COMBINATION OF WARMTH AND MOISTURE
WILL DRIVE THE HEAT INDEX TO NEAR 100 AGAIN ON THURSDAY IN THE
PIEDMONT...SEVERAL DEGREES BELOW THE ADVISORY CRITERIA OF 105
DEGREES.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 250 PM WEDNESDAY...EXPECT CONVECTION THU NITE TO BE MAINLY
DIURNAL...BUT ISOLATED CELLS COULD LINGER IN THE MTNS OVERNIGHT.
LOWS WILL BE ABOVE NORMAL.

A SHORT WAVE DIVES INTO THE OH VALLEY FRIDAY PUSHING A COLD FRONT
SOUTH TOWARD THE AREA. THIS WAVE SLOWLY MOVES SOUTH AND EAST TOWARD
THE VA TIDEWATER AND MID-ATLANTIC AREA. THE SFC FRONT WILL SLOWLY
PUSH INTO THE AREA ON SATURDAY. MOISTURE WILL BE COPIOUS AHEAD OF
AND ALONG THE FRONT. QG FORCING WILL BE WEAK...BUT LOW LEVEL
CONVERGENCE ALONG THE FRONT WILL BE DECENT...ALONG WITH UPPER LEVEL
DIVERGENCE ASSOCIATED WITH AN UPPER JET. THEREFORE...EXPECT NUMEROUS
SHOWERS AND THUNDERSTORMS FRIDAY...WITH NUMEROUS COVERAGE I-85 AND
SOUTH AND GOOD CHC NORTH SATURDAY. CONVECTION WILL STILL SHOW A
DIURNAL TREND...BUT WILL NOT DIMINISH UNTIL LATE AT NITE. WITH A
VERY MOIST AIR MASS AND SLOW MOVING STORMS...HEAVY RAIN WILL BE
POSSIBLE.

HIGHS FRIDAY STILL NEAR TO SLIGHTLY ABOVE NORMAL...THEN DROPS BELOW
NORMAL SATURDAY. LOWS FRIDAY NITE ABOVE NORMAL.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 1245 PM WEDNESDAY...THE LATEST GUIDANCE KEEPS A STATIONARY
FRONT OVER THE AREA SUNDAY. THE FRONT BEGINS TO WASH OUT MONDAY AS
THE BERMUDA HIGH POKES BACK INTO THE REGION FROM THE EAST.
HOWEVER...A SHEAR AXIS AND A BAND OF DEEP MOISTURE WILL REMAIN OVER
THE AREA MONDAY IN THE WEAKNESS BETWEEN THE BERMUDA HIGH AND THE
STRONG RIDGE OVER THE CENTRAL CONUS. THE RIDGE AND THE BERMUDA HIGH
MERGE TUESDAY AS A TROF MOVES OFF SHORE OF NEW ENGLAND...BUT THE
DEEP MOISTURE AND A LEE TROF REMAIN OVER MUCH OF THE SERN US. THE
CENTER OF THE RIDGE IS PUSHED SOUTH INTO THE GULF WEDNESDAY...BUT
RIDGE AXIS REMAINS OVER OUR AREA...AS ANOTHER TROF DROPS FROM CANADA
INTO THE NRN PLAINS. THIS HELPS PUSH A BACK DOOR COLD FRONT TOWARD
THE AREA DURING THE DAY.

ALTHOUGH A GOOD CHANCE OF CONVECTION AGAIN ON SUNDAY...GUIDANCE
DIFFERS ON BETTER CHANCES FOR ONE AREA OR ANOTHER. THEREFORE...HAVE
GONE WITH CHC POP FOR NOW. OTHERWISE...MAINLY DIURNAL CHC POP MON
THRU WED WITH THE MOISTURE AND WEAK FORCING IN PLACE. ABOVE NORMAL
LOWS AND BELOW NORMAL HIGHS AGAIN SUNDAY...THEN THE HEAT BUILDS WITH
THE RIDGE. HIGHS RISING INTO THE MID 90S BY WED WITH LOW TO MID 70S
EACH MORNING.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
AT KCLT...SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON. BASED THE
SLOWER THAN ANTICIPATED DEVELOPMENT...CONFIDENCE IS A LOWER FOR A
RESTRICTION...AND NONE WILL BE CARRIED AT THIS TIME. TS WITH A LOW
VFR CIG WILL BE CARRIED. LIGHT SW WINDS WILL PERSIST. A CONSENSUS OF
GUIDANCE DOES NOT SUPPORT DAYBREAK FOG ON THURSDAY. ALTHOUGH THE
CHANCE OF PRECIPITATION WILL INCREASE ON THURSDAY MORNING AS A FRONT
APPROACHES FORM THE NORTH...CHANCES ARE STILL TOO LOW MENTION A
RESTRICTION.

ELSEWHERE...CONVECTION WILL DEVELOP THIS AFTERNOON...WITH THE BEST
COVERAGE IN THE MOUNTAINS. A TEMPO FOR THUNDERSTORM BASED MVFR
RESTRICTIONS WILL BE CARRIED AT KAVL...WHILE FOOTHILLS SITES GET TS
AND A LOW VFR CIG WITH CB. LIGHT WINDS WILL REMAIN FROM THE SW TO
WSW...EXCEPT AT KAVL WHERE THEY WILL CHANNEL UP THE VALLEY FORM THE
NW. AT THIS TIME GUIDANCE PLACES FOG IN THE MOUNTAIN VALLEYS SW OF
KAVL. BASED ON THE TRENDS FROM THIS MORNING...FOG WILL BE CARRIED AT
KAVL AND KAND AS WELL. CHANCES FOR CONVECTION INCREASE ON THURSDAY
AS A FRONT APPROACHES FROM THE NORTH...BUT CONFIDENCE IS TOO LOW TO
CARRY A RESTRICTION.

OUTLOOK...SCATTERED THUNDERSTORMS WILL CONTINUE LATE
THURSDAY...ESPECIALLY OVER THE NC MOUNTAINS. A WEAK COLD FRONT WILL
REACH THE AREA ON FRIDAY...REMAINING INTO THE WEEKEND...AND
INCREASING THE CHANCE OF THUNDER...LOW CIGS...AND FOG.

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...PAT
NEAR TERM...JAT
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...JAT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
407 PM EDT WED JUL 18 2012

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-192015-
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-
407 PM EDT WED JUL 18 2012

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

.DAY ONE...TONIGHT.

NUMEROUS SLOW MOVING THUNDERSTORMS WILL CONTINUE TO DEVELOP OVER
THE REGION THROUGH THE EVENING. A FEW OF THE THUNDERSTORMS WILL
PRODUCE SMALL AREAS OF WIND DAMAGE AND HAIL UP TO THE SIZE OF
QUARTERS. LOCALLY VERY HEAVY RAINFALL IS ALSO POSSIBLE WITH THE
STRONGER STORMS AND FLOODING OF POOR DRAINAGE AREAS MAY DEVELOP.
MANY OF THE STORMS WILL PRODUCE FREQUENT CLOUD TO GROUND LIGHTING.

THE EFFECTS OF HEAVY RAIN AND SATURATED SOILS WILL ENHANCE THE
THREAT OF FALLING TREES.

.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.

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