Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
228 PM EDT SUN MAY 6 2012

.SYNOPSIS...
A NEARLY STATIONARY FRONT WILL REMAIN OVER TENNESSEE AND GEORGIA
TONIGHT AND THEN LIFT NORTH AS A WARM FRONT BY MONDAY NIGHT.  EXPECT
A COLD FRONT TO APPROACH FROM THE MISSISSIPPI AND OHIO VALLEYS
TUESDAY AND REACH OUR REGION ON WEDNESDAY.  DRIER...COOLER HIGH
PRESSURE WILL BUILD ACROSS OUR AREA IN THE LAST HALF OF THE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 225 PM EDT...UPPER LEVEL HEIGHTS ARE RISING ACROSS THE REGION
THIS AFTN...BUT WITH A PESKY VORT MAXIMUM WRAPPING UNDER THE RIDGE
ACROSS THE SRN HALF OF THE FORECAST AREA THROUGH LATE DAY. ON
RADAR...THE WEAK PIEDMONT SHOWER ACTIVITY WITH THIS WAVE HAS ALREADY
PASSED SE OF THE AREA...SO ANY ADDITIONAL TRIGGERING FOR CONVECTION
SHOULD BE UPSLOPE FLOW INTO THE HIGHER TERRAIN THROUGH THE REST OF
THE PERIOD. THE FOCUS OF CONVECTION THIS AFTN WILL THUS BE ACROSS
THE SRN APPALACHIANS...WITH UPSLOPE TRIGGERING ON THE E SIDE...AND
WEAK WIND CONVERGENCE ACROSS THE REST OF THE MTN CHAIN. LAPS SFC
BASED CAPE VALUES HAVE POOLED IN THE 1000 TO 2000 J/KG RANGE IN THE
SRN MTNS THIS AFTN...HOWEVER...PROFILES DO NOT LOOK ESPECIALLY
FAVORABLE FOR SEVERE WEATHER GIVEN THE FAIRLY WEAK LAPSE RATES
ALOFT. BUT...WITH FREEZING LEVELS AROUND 12.5 KFT AND MINUS 20C
TEMPS AT 23 KFT ON LAPS SOUNDINGS...ANY 55 DBZ CORE HEIGHTS TO 23
KFT WOULD BE MARGINAL FOR LARGE HAIL. LOCALLY HEAVY RAINFALL SHOULD
BE THE BIGGER THREAT AS THERE IS VERY LITTLE STEERING FLOW UP THE
COLUMN THROUGH TONIGHT. WILL NEED TO KEEP AT LEAST ISOLD TO SCT
SHOWERS GOING OVER THE MTNS AS SE UPSLOPE PERSISTS OVERNIGHT...AND
PERHAPS IMPROVES. WIDESPREAD LOW STRATUS SHOULD DEVELOP THROUGHOUT
IN THE MOIST EASTERLY FLOW.

THE UPPER RIDGE WILL HOLD ON THROUGH THE DAY ON MONDAY. ALTHOUGH SFC
HIGH PRES WILL BE IN A CAD LIKE CONFIGURATION...THICKNESSES REMAIN
FAIRLY WARM AND THE SHOWER COVERAGE MAY BE SPOTTY. SOME BREAKS COULD
THUS DEVELOP THROUGH THE DAY ALLOWING TEMPS TO RECOVER INTO THE
UPPER 70S TO NEAR 80 OUTSIDE OF THE MTNS. THE BEST COMBINATION OF
INSTABILITY AND UPSLOPE FORCING WILL CONTINUE OVER THE
MTNS...ESPECIALLY IN SRN SECTIONS...THROUGH MON AFTN. LOW LEVELS
WILL REMAIN QUITE MOIST...BUT WITH INSTABILITY STILL LIMITED BY
CLOUD COVER AND UNIMPRESSIVE LAPSE RATES ALOFT.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 150 PM SUNDAY...A COMBINATION OF A VERY MOIST AIR MASS AND
SOUTHEAST UPSLOPE FLOW (ALBEIT WEAK) SHOULD RESULT IN CONVECTION
CONTINUING WELL INTO THE EVENING HOURS ACROSS THE WESTERN ZONES
MONDAY. THE FLOW WILL BEGIN TO TURN TOWARD THE SOUTHWEST LATE...SO A
GRADUAL DECREASE IN CONVECTION IS EXPECTED OVERNIGHT...ALTHOUGH
SHEARING MID-LEVEL VORT MAX WARRANTS CONTINUATION OF CHANCE POPS
OVER THE HIGHER TERRAIN THROUGH 12Z. AS THE VERY MOIST AIR MASS
DESTABILIZES DURING THE AFTERNOON...AND A LOW LEVEL CONFLUENT AXIS
SETS UP OVER THE HIGHER TERRAIN...CONVECTIVE CELLS SHOULD BECOME
NUMEROUS DURING THE AFTERNOON OVER THE HIGHER TERRAIN...AND 70 POPS
WILL BE CARRIED FROM THE AFTERNOON INTO THE EVENING...WITH POPS
TAPERING TO A CHANCE ACROSS THE EASTERN AND SOUTHERN ZONES.

GRADUAL DIMINISHMENT IN CONVECTIVE COVERAGE IS ANTICIPATED ACROSS
THE AREA TUESDAY NIGHT. HOWEVER...HEIGHTS WILL BEGIN TO FALL
UPSTREAM TUESDAY NIGHT...AS A STRONG SHORT WAVE TROUGH SWINGS ACROSS
THE MIDWEST...DRIVING A SLOW-MOVING COLD FRONT TOWARD THE AREA BY
DAYBREAK WEDNESDAY. THERE IS NOT A GREAT DEAL OF LOW LEVEL FORCING
ASSOCIATED WITH THE FRONT...AND LITTLE IN THE WAY OF UPPER SUPPORT
TO INTERACT WITH IT...SO I FEEL THAT THE BEST COVERAGE OF CONVECTION
SHOULD STILL BE STRONGLY TIED TO THE DIURNAL HEATING CYCLE.
THEREFORE...WILL RAMP UP POPS QUICKLY DURING THE DAY ON WEDNESDAY...
WITH MOST AREAS GETTING A 50-70% CHANCE BY AFTERNOON.

MAX TEMPS SHOULD BE AROUND NORMAL THROUGH THE PERIOD...OWING TO HIGH
COVERAGE OF CONVECTION/EXTENSIVE CONVECTIVE DEBRIS. MEANWHILE...LOWS
SHOULD BE WELL ABOVE NORMAL IN THE VERY MOIST AIR MASS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 150 PM SUNDAY...THERE IS GOOD AGREEMENT IN THE DAYS 5 THROUGH
7 PERIOD WITH SOME DIFFERENCES AT THE END.  AT THE START OF THE
PERIOD THERE WILL BE ONGOING CONVECTION AT 00Z THURSDAY CONSIDERING
400 TO 1000 CAPE ALONG AND SOUTH OF INTERSTATE 85.  THAT MOVES OUT
RATHER QUICKLY AND DRYING FROM THE WEST OCCURS LATE WEDNESDAY NIGHT
WITH HIGH PRESSURE CROSSING THE MID AND UPPER MISS VALLEY THURSDAY.
WITH THE GRADIENT BETWEEN THE DEPARTING LOW OVER THE MID ATLANTIC
AND THE HIGH TO THE WEST...WIND COULD BE BREEZY OVER THE MOUNTAINS
ON THURSDAY.  THE HIGH WILL BE CENTERED NEAR OUR REGION ON FRIDAY
PROVIDING DRY WEATHER WITH CALM TO LIGHT WIND.  THE MODELS AGREE
THAT A TROUGH WILL DROP DOWN ACROSS THE MISS VALLEY BY LATE IN THE
WEEKEND AS IT HEADS OUR WAY.  CLOUDINESS SHOULD BEGIN TO INCREASE
SATURDAY NIGHT INTO SUNDAY.  SURFACE FRONT SHOULD BE ACROSS OHIO
VALLEY BY LATE SUNDAY.  BOTH GFS AND ECMWF HAVE EASTERN GULF
CONVECTION LATE SUNDAY AND MOVES SOME OF THAT NE TOWARD US TO START
THE WEEK. FOR NOW...HAVE SLIGHT POPS INCREASING A BIT GOING INTO
SUNDAY NIGHT MAINLY OVER NC MOUNTAINS. TEMPERATURES WILL BE NEAR OR
SLIGHTLY BELOW NORMAL.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
AT KCLT...ANY MID DAY SHOWERS ASSOCIATED THE PASSAGE OF A WEAK UPPER
VORT UNDER THE RIDGE HAVE MOVED SOUTH OF THE KCLT VICINITY. ANY
ADDITIONAL CONVECTIVE TRIGGERING THIS AFTN SHOULD BE MAINLY
OROGRAPHICALLY FORCED NEAR THE MTNS. THUS WILL NOT FEATURE PRECIP OR
TS AT KCLT THROUGH THE PERIOD. THE MAIN FORECAST ISSUE WILL BE
CLOUDS...AS GOOD CONSENSUS EXISTS ON THE CURRENT VFR CIGS LOWERING
TO MVFR BY AROUND 05Z...THEN IFR OR LOWER BY 08Z. MODEL PROFILES ARE
A BIT MIXED ON THE POTENTIAL FOR LIFR OR VLIFR CIGS IN THE MOIST
EASTERLY FLOW...SO WILL KEEP THE FORECAST AT IFR FOR NOW. CIGS
SHOULD SLOWLY RECOVER THROUGH THE LATE MORNING HOURS TO LOWER VFR
CIGS NEAR THE END OF THE PERIOD. WILL KEEP WINDS ENE AT 10 KT THIS
AFTN AND LIGHT OVERNIGHT...BUT WITH A SUBTLE SWITCH TO LIGHT ESE
AFTER 16Z.

ELSEWHERE...THE BEST POTENTIAL FOR TSRA OR SHRA LATE THIS
AFTN/EVENING WILL BE NEAR KAVL AS UPSLOPE FLOW AND WEAK WIND
CONVERGENCE PROVIDE THE BEST FORCING IN AND NEAR THE MTNS. CIGS
SHOULD BE MAINLY VFR...BUT WITH CLOUD HEIGHTS LOWERING THROUGH MVFR
TO IFR DURING THE EARLY MORNING HOURS IN MOIST EASTERLY FLOW.
SCATTERED SHOWERS COULD CONTINUE THROUGH THE OVERNIGHT HOURS IN THE
MTNS AS THE SE UPSLOPE FLOW IN THE BOUNDARY LAYER PERSISTS...BUT
WILL END THE VICINITY MENTION BY 03Z FOR NOW. VERY SLOW RECOVERY IN
THE CIGS TO LOWER VFR IS EXPECTED THROUGHOUT ON MONDAY MORNING AS
MOIST SE UPSLOPE FLOW CONTINUES.

OUTLOOK...SHOWER AND THUNDERSTORM COVERAGE WILL INCREASE TUE THROUGH
WED AS A COLD FRONT APPROACHES FROM THE WEST. MAINLY NIGHTTIME
FOG/STRATUS PROBLEMS ARE EXPECTED...EXCEPT FOR RESTRICTIONS IN
THUNDERSTORMS AT ANY HOUR. MUCH DRIER CONDITIONS WILL ARRIVE THU
THROUGH FRI BEHIND THE PASSING COLD FRONT.

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...DEO
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...DEO
AVIATION...HG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
233 PM EDT SUN MAY 6 2012

NCZ035>037-056-057-068>072-082-SCZ008-009-013-014-071845-
ALEXANDER-IREDELL-DAVIE-CATAWBA-ROWAN-CLEVELAND-LINCOLN-GASTON-
MECKLENBURG-CABARRUS-UNION NC-CHEROKEE-YORK-UNION SC-CHESTER-
233 PM EDT SUN MAY 6 2012

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

GAZ010-017-018-026-028-029-NCZ033-048>053-058-059-062>065-501>510-
SCZ001>007-010>012-019-071845-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-MADISON-YANCEY-
MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-NORTHERN JACKSON-MACON-
SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-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-ANDERSON-ABBEVILLE-LAURENS-GREENWOOD-
233 PM EDT SUN MAY 6 2012

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS THE
SOUTHERN APPALACHIANS THIS AFTERNOON AND EVENING. ISOLATED
THUNDERSTORMS COULD ALSO DEVELOP IN NEARBY NORTH CAROLINA FOOTHILL
LOCATIONS...THROUGHOUT THE WESTERN UPSTATE...AND ACROSS NORTHEAST
GEORGIA. THE THUNDERSTORMS WILL BE VERY SLOW MOVING AND COULD
PRODUCE LOCALLY EXCESSIVE RAINFALL...WITH ISOLATED FLOODING
RESULTING. CLOUD TO GROUND LIGHTNING STRIKES WILL ALSO ACCOMPANY
ANY THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ASKED TO RELAY ANY REPORTS OF FLOODING TO THE
NATIONAL WEATHER SERVICE.

GERAPETRITIS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
403 PM EDT SUN MAY 6 2012

NCZ048-049-053-062030-
BUNCOMBE-MADISON-YANCEY-
403 PM EDT SUN MAY 6 2012

...A STRONG THUNDERSTORM WILL AFFECT EASTERN MADISON...NORTHERN
BUNCOMBE AND WESTERN YANCEY COUNTIES THROUGH 430 PM EDT...

AT 402 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 4 MILES EAST OF MARS HILL...OR 11 MILES EAST OF
MARSHALL...MOVING NORTH AT 5 MPH.

THIS STORM WILL BE NEAR...
  MARS HILL...

HEAVY RAIN...PEA SIZE HAIL...AND WIND GUSTS OF 30 TO 40 MPH ARE
EXPECTED WITH THIS STORM.

LAT...LON 3601 8240 3576 8235 3572 8257 3596 8267
      3597 8259 3596 8256 3598 8254 3599 8249

RB