Severe Thunderstorm Warning 48, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
427 PM EDT FRI MAY 23 2014

.SYNOPSIS...
A WEAK COLD FRONT WILL STALL OUT OVER GEORGIA TONIGHT. SURFACE HIGH
PRESSURE WILL THEN DRIFT EASTWARD FROM THE OHIO VALLEY TO THE
OFFSHORE ATLANTIC WATERS OVER THE WEEKEND. THE REGION IS EXPECTED TO
BE BACK UNDER THE INFLUENCE OF THE BERMUDA HIGH BY EARLY NEXT WEEK
WITH DEWPOINTS AND TEMPERATURES WARMING.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 425 PM EDT FRIDAY...SCATTERED CONVECTION WILL CONTINUE ACROSS
PORTIONS OF THE UPSTATE THROUGH THE REMAINDER OF THE AFTERNOON.  THE
ATM REMAINS UNSTABLE ALONG AND SOUTH OF INTERSTATE 85 WITH A
PLUME OF SBCAPE IN EXCESS 2500 JOULES ACROSS THE WESTERN UPSTATE AND
PORTIONS OF NORTHEAST GA...PER 20Z MESOANALYSIS.  WOULD NOT BE
SURPRISED TO SEE FURTHER INITIATION TO THE WEST ACROSS AREAS THAT
HAVE NOT BEEN WORKED OVER BY PAST/PRESENT CONVECTION...SPECIFICALLY
WEST OF I26 IN SC/GA WHERE CU FIELD REMAINS PREVALENT.
THUS...INCREASED POPS DRASTICALLY ACROSS THE UPSTATE TO ACCOUNT FOR
CONTINUED DEVELOPMENT THROUGH EARLY EVENING.  HAIL REMAINS THE
PRIMARY THREAT WITH ANY DEEPER CONVECTION AS MULTIPLE REPORTS OF
QUARTER TO TENNIS BALL SIZED HAIL HAVE BEEN RECEIVED.  NO CHANGES
PLANNED TO WATCH BOX AT THIS TIME.

PREVIOUS DISCUSSION...

AS OF 230 PM EDT...CONVECTION REMAINS LARGELY BENIGN ATTM WITH
MAINLY SCT CU OVER SOME OF THE MTNS AND WRN UPSTATE. UNDER STILL
BRISK MID-UPPER LEVEL NW FLOW...MTN WAVE CIRRUS CONTINUE TO KEEP
MCLDY SKIES OVER THE NC FOOTHILLS AND NW PIEDMONT. THESE AREAS WERE
HIT PRETTY HARD WITH OUTFLOW FROM THE TSTM CLUSTER THIS MORNING AND
APPEAR TO HAVE BEEN KEPT STABLE BY THIS AND TO SOME EXTENT THE
CIRRUS. S AND W OF THIS AREA ISOLATED TSRA ARE STILL
EXPECTED...WHERE 1500-2000 J OF UNCAPPED SBCAPE IS SHOWN ON SPC
MESOANALYSIS. INDEED A COUPLE OF CELLS ARE STARTING TO GO UP OVER
PICKENS COUNTY. THE 12Z NCEP HIRES WINDOW RUNS REINFORCE SUGGESTIONS
OF NUMEROUS HRRR AND RAP RUNS THAT ISOLD ACTIVITY WILL KICK OFF IN
THE SMOKIES AND IN THE UPSTATE EAST OF SPARTANBURG. WITH THE
AFOREMENTIONED INSTABILITY AND EFFECTIVE BULK SHEAR OF 35-45
KT...ALONG WITH SUBSTANTIAL DCAPE OVER 1000 J/KG...STORMS WILL BE
QUITE CAPABLE OF DMGG WIND/HAIL. SVR WATCH JUST ISSUED FOR THE SRN
TIER OF THE NC MTNS/FOOTHILLS...THE UPSTATE AND NE GA.

HIGH PRESSURE BEGINS TO BUILD ACRS THE GREAT LAKES AND OHIO VALLEY
THRU TONIGHT. COLD FRONT CONTINUES TO BE PROGGED TO PUSH SWD THRU
MOST OF THE NC MTNS AND PIEDMONT BY DAYBREAK...PUSHING THROUGH THE
ERN SC PIEDMONT THEREAFTER. IN THE WAKE OF THE FRONT THINGS REMAIN
STABLE THROUGH THE DAY. HOWEVER...WITH A FAIRLY FLAT UPPER RIDGE
REMAINING OVER THE GULF STATES...THE FRONT DOES NOT APPEAR TO FULLY
IMPACT THE SAVANNAH RIVER VALLEY AND WRN UPSTATE. HOWEVER SUBSIDENCE
ALOFT APPEARS TO BE ENOUGH TO WEAKEN LAPSE RATES TO THE POINT THAT
ONLY LIMITED CONVECTION WILL BE POSSIBLE IN THIS AREA. GFS AND NAM
CONTINUE TO PRODUCE HEFTY SBCAPE VALUES OVER 1000 J/KG WEST OF
GSP...BUT SREF PROBS SUGGEST VALUES MOST LIKELY WILL NOT GET THIS
HIGH. I WILL INCLUDE A SCHC FOR DIURNAL SHWRS/TSTMS ALONG THE SRN
ESCARPMENT AND AREAS JUST SOUTH WHERE THE BEST INSTABILITY IS
SUGGESTED. HIGHS WILL BE NEAR NORMAL IN THE MORE CONTINENTAL AIRMASS
BUT WITH BRIGHT SUNSHINE.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM FRIDAY...ONLY SUBTLE CHANGES ARE EXPECTED TO THE
OVERALL UPPER PATTERN FROM SUNDAY INTO MONDAY...MEANING WE SHOULD
REMAIN UNDER A NW FLOW ALOFT BUT THAT HEIGHTS SHOULD RISE A BIT AS
THE TROF OFF THE EAST COAST DEAMPLIFIES. THIS PATTERN WILL ALLOW THE
CENTER OF SURFACE HIGH PRESSURE TO MIGRATE FROM THE MIDWEST/OH
VALLEY REGION TO A POSITION OFF THE SOUTHEAST COAST ON SUNDAY. ONCE
THIS HAPPENS...WE CAN EXPECT SOME RETURN OF MOISTURE FROM THE SOUTH
AND SOME WEAK WARM ADVECTION. THAT WILL PUT THE WESTERN CAROLINAS
AND NE GEORGIA BACK INTO A REGIME WHERE MAINLY DIURNAL SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE. PRECIP CHANCES WERE LIMITED TO A
SLIGHT CHANCE ACROSS MOST OF THE AREA SUNDAY OWING TO THE LACK OF
DEVELOPMENT SEEN IN THE NAM...BUT THEN WERE ALLOWED TO GO UP TO A
CHANCE ACROSS MOST OF THE REGION MONDAY AS MOISTURE AND INSTABILITY
WERE INCREMENTALLY BETTER. TEMPS WILL CREEP UP A BIT FOR SUNDAY...
AND THEN RISE ABOUT A CATEGORY HIGHER FOR MONDAY...AROUND 80 IN THE
MTN VALLEYS AND MIDDLE 80S E OF THE MTNS.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z ON
TUESDAY WITH THE PERSISTENT UPPER RIDGE ANCHORED OVER THE CENTRAL
CONUS AND AN EMBEDDED H5 LOW DRIFTING SLOWLY EASTWARD OVER THE
SOUTHERN PLAINS. SIMULTANEOUSLY...A CLOSED UPPER LOW IS EXPECTED TO
DROP DOWN OVER EXTREME NORTHERN NEW ENGLAND AND REMAIN OVER THAT
REGION FOR MOST OF THE PERIOD. IN TERMS OF THE SYNOPTIC PATTERN
EVOLUTION OVER OUR REGION...WE DONT EXPECT ANY SIG CHANGES THRU DAY
7 WITH THE DOMINANT UPPER RIDGE REMAINING IN PLACE THRU THE PERIOD.

AT THE SFC...WE BEGIN THE PERIOD UNDER LIGHT SLY FLOW WITH A TYPICAL
BERMUDA HIGH IN PLACE TO OUR EAST. EARLY IN THE DAY...A FAIRLY
ROBUST LOW DEEPENS OVER EXTREME NORTHERN NEW ENGLAND AND BRINGS A
SWATH OF COOLER AND DRIER AIR TOWARDS THE FCST AREA. THE MODELS
DIFFER ON HOW FAR SOUTH THIS LOW WILL MAKE WITH THE GFS BRINGING IT
QUITE A BIT FARTHER SOUTH THAN THE ECMWF AND CMC MODELS. I WILL
CONTINUE TO PUT MORE EMPHASIS ON THE ECMWF AND CMC SOLUTIONS FOR THE
TIME BEING AND THUS I DONT EXPECT THE COOLER/DRIER AIR TO PENETRATE
AS FAR SOUTH AS THE GFS SUGGESTS. ONCE THIS LOW MOVES WELL
OFFSHORE...ANOTHER CANADIAN HIGH TRIES TO PUSH SOUTHWARD AND INTO
THE REGION...HOWEVER ITS LOOKING LIKE IT WILL DISSIPATE FAIRLY QUICKLY
ONCE IT MAKES TO THE CAROLINAS.

AT ANY RATE...NO MAJOR CHANGES WERE NEEDED TO THE SENSIBLE FCST. I
DID INCREASE POPS OVER SOME PORTIONS OF THE CWFA TO SOLID CHANCE FOR
WIDELY SCT DIURNAL SHOWERS AND TS FOR WED AND THURS. OTHERWISE...I
CARRY A SLIGHT TO SOLID CHANCE FOR SH AND TS EACH DAY OF THE PERIOD.
IN ADDITION...IT IS TOO EARLY TO MENTION ANY THREAT OF SVR OR WELL
ORGANIZED CONVECTION AT THIS POINT. TEMPS SHOULD START OUT 5 TO 10
DEGREES ABOVE NORMAL FOR LATE MAY AND GRADUALLY DROP THRU THE PERIOD
WITH HIGHS RIGHT AROUND NORMAL BY NEXT FRIDAY.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...FOLLOWING THE CONVECTION WHICH MOVED THRU THIS MORNING AND
LEFT BEHIND COOLER AND MORE STABLE AIR...THREAT OF TSRA THIS AFTN
APPEARS TO HAVE BEEN MITIGATED TO THE POINT THAT A TEMPO IS NO
LONGER WARRANTED. HOWEVER...THERE IS STILL A VERY SMALL CHANCE A
STORM COULD AFFECT THE FIELD WITH GUSTY WINDS AND POSSIBLY HAIL. A
FEW LOW VFR CU ARE LIKELY TO PERSIST AT ANY RATE. GENERALLY NW WINDS
WILL PRECEDE OVERNIGHT ARRIVAL OF BACKDOOR COLD FRONT...WHICH SHOULD
BRING WINDS N TO NNE AND VIRTUALLY CLEAR SKIES. PROFILES LOOK
UNFAVORABLE FOR FOG WITH LLVL DRYING IN THE WAKE OF THE FRONT.

ELSEWHERE...ISOLD SHRA/TSRA ARE EXPECTED THIS AFTN IN THE MTNS OF SW
NC...SC AND GA...AS WELL AS IN THE AREA GENERALLY SOUTH OF I-85. THE
TSRA WILL BE CAPABLE OF VERY GUSTY WINDS AND HAIL. THIS ACTIVITY
WILL BE DIURNALLY DRIVEN AND SHOULD NOT PERSIST INTO THE EVENING.
WINDS GO NORTHERLY OVERNIGHT AS COLD FRONT PUSHES IN. SHOULD REMAIN
TOO DRY FOR FOG EXCEPT PERHAPS IN MTN VALLEYS. THE FRONT MAY HANG UP
OVER THE SAVANNAH RIVER VALLEY AND CAUSE WINDS TO RETURN TO SW AFTER
DAYBREAK AT KAND/KGMU/KGSP. CONFIDENCE ON THIS IS LOW SO NO MENTION
WAS MADE IN THE TAF.

OUTLOOK...DRY HIGH PRESSURE BUILDS IN SATURDAY. VERY ISOLATED
SHRA/TSRA ARE POSSIBLE SAT/SUN AFTNS. AFTN CONVECTION COVERAGE IS
EXPECTED TO INCREASE SOMEWHAT FOR MONDAY AND TUESDAY...AS DEEPER
MOISTURE RETURNS.

CONFIDENCE TABLE...

            20-02Z        02-08Z        08-14Z        14-20Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     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...JPT
NEAR TERM...CDG/WIMBERLEY
SHORT TERM...PM
LONG TERM...JPT
AVIATION...WIMBERLEY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
411 AM EDT FRI MAY 23 2014

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-240815-
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-
411 AM EDT FRI MAY 23 2014

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 MOVING SLOWLY SOUTHWARD THROUGH THE REGION TODAY WILL
GENERATE ISOLATED TO SCATTERED THUNDERSTORMS...MAINLY THIS
AFTERNOON AND EVENING. ALTHOUGH THE COVERAGE OF THE THUNDERSTORMS
IS NOT EXPECTED TO BE VERY WIDESPREAD...JUST ABOUT ANY
THUNDERSTORM THAT DEVELOPS LATE TODAY WILL HAVE THE POTENTIAL TO
PRODUCE BRIEF BUT DAMAGING WIND GUSTS AND HAIL THE SIZE OF
QUARTERS. IN ADDITION...BRIEF HEAVY DOWNPOURS AND FREQUENT CLOUD
TO GROUND LIGHTNING WILL ACCOMPANY ANY THUNDERSTORM. THE GREATEST
COVERAGE OF THUNDERSTORMS LATE TODAY WILL BE ALONG AND SOUTHEAST
OF INTERSTATE 85...ESPECIALLY ACROSS THE CHARLOTTE METRO AREA AND
THE EASTERN UPSTATE OF SOUTH CAROLINA.

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

..SATURDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..SUNDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..MONDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..TUESDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..WEDNESDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..THURSDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE ASKED TO RELAY ANY REPORTS OF LARGE HAIL OR
DAMAGING WINDS TO THE NATIONAL WEATHER SERVICE.

HG

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