Severe Thunderstorm Warning 170, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
246 PM EDT THU JUN 19 2014

.SYNOPSIS...
HIGH PRESSURE WILL WEAKEN AS AN UPPER RIDGE GRADUALLY BREAKS DOWN
TONIGHT AND FRIDAY. THIS SHOULD YIELD A GREATER COVERAGE OF SHOWERS
AND THUNDERSTORMS ACROSS THE ENTIRE AREA OVER THE WEEKEND. TYPICAL
SUMMERTIME WEATHER CONTINUES ACROSS THE REGION NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 215 PM EDT...ISOLD DEEP CONVECTION HAS KICKED OFF OVER THE
HIGHER MTNS...WITH CELLS LINED UP UPSTREAM ACRS THE GREAT TENN VALLEY
AS WELL...UNDER A WEAK SHORTWAVE ROUNDING THE RIDGE OVER THE SERN
STATES. ACTIVITY ALONG THE OLD OUTFLOW BDY ACRS FAR ERN KY AND SRN WV
STILL SAGGING SOUTH. LATEST MESO MODELS SHOW BOTH OF THESE LINEAR
FEATURES MOVING TOWARD OUR CWFA THRU THE REST OF THE AFTN. INFLOW
WINDS ARE WEAK...BUT INSTABILITY AHEAD OF THE LINES IS STRONG AS ONE
MIGHT EXPECT. IT LOOKS LIKE THE MESO GUIDANCE IS SUGGESTING MORE OF A
PROPAGATION INTO OUR AREA AND SUBSEQUENT REDEVELOPMENT ALONG REMNANT
BOUNDARIES. NONETHELESS...HIGHEST POPS REMAIN OVER THE MTNS WITH A
LATER INCREASE IN POPS OVER THE PIEDMONT AS ROUNDS OF STORMS FORM
ACRS THE AREA.

TONIGHT...MOST OF THE ENERGY WITH THE AFOREMENTIONED SHORTWAVE MOVES
OFF THE MID-ATLANTIC COAST BUT SOME WEAK DPVA MAY TRAIL IT...MOVING
SEWD ACRS THE CWFA THIS EVENING. A MINOR LLVL BOUNDARY IS SHOWN TO
MOVE SWD IN THE WAKE OF THE WAVE AS HIGH PRESSURE BUILDS SLIGHTLY S
AND E OUT OF THE GREAT LAKES AREA. SOME LINGERING MUCAPE IS SHOWN
THOUGH IT DIMINISHES AND IS INHIBITED AND WELL ELEVATED ANYWAY. IT
APPEARS MOST LIKELY THAT ANY REMAINING CONVECTION ALONG BOUNDARIES IN
OR INVOF THE FA WILL DIMINISH EXCEPT PERHAPS IN THE MTNS. LOWS WILL
BE NEAR NORMAL.

FRIDAY...FLOW ACRS THE SRN CONUS GENERALLY BECOMES MORE ZONAL.
NORTHERLY FLOW PERSISTS WITH LOW PRS OFF THE ATLANTIC COAST AND SOME
SEMBLANCE OF THE BOUNDARY REMAINING IN THE AREA...THOUGH ONLY
PROVIDING VERY WEAK CONVERGENCE. OVERALL...THE FA REMAINS UNDER
WEAKLY SHEARED BUT SEASONABLY HOT AND UNSTABLE CONDITIONS. LAPSE
RATES ARE SHOWN TO BE A LITTLE WEAKER THAN THOSE SEEN TODAY...WITH
LOWER CAPE VALUES DURING PEAK HEATING. VALUES HOWEVER REMAIN HIGH
ENOUGH TO EXPECT A SMALL SEVERE THREAT...FROM DOWNBURST WIND AND
HAIL.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 145 PM THURSDAY...CHANGES TO THE OVERALL PATTERN WILL BE
TYPICALLY SUBTLE DURING THE SHORT TERM PERIOD...AND ARE UNLIKELY TO
HAVE A GREAT DEAL OF IMPACT ON THE SENSIBLE WEATHER. THE UPPER RIDGE
IS FORECAST TO SLOWLY RETROGRADE TOWARD THE SOUTH CENTRAL CONUS AND
WEAKEN DURING THE PERIOD...PLACING THE SOUTHEAST AND MID-ATLANTIC
ALONG THE SOUTHERN PERIPHERY OF THE WESTERLIES...WITH A DEEP NW FLOW
ANTICIPATED ACROSS OUR AREA. WHILE THIS WILL THEORETICALLY RENDER
THE AREA MORE SUSCEPTIBLE TO ORGANIZED CONVECTION MOVING OUT OF THE
OHIO VALLEY REGION...BASED UPON WIND PROFILES...IT IS DOUBTFUL THAT
ANYTHING TOO ORGANIZED AND SELF-SUSTAINING WILL BE ABLE TO DEVELOP
UPSTREAM...AS ONE MAY NEED TO TRAVEL AS FAR NORTH AS THE CANADIAN
BORDER TO FIND ROBUST SHEAR. NEVERTHELESS...WITH A WEAK COLD FRONT
APPROACHING THE REGION...AND HALFWAY DECENT STEERING CURRENTS (MEAN
CLOUD BEARING WINDS ON THE ORDER OF 15-20 KTS...ABOVE CLIMO POPS
(GENERALLY 30-40 PERCENT DURING THE AFTERNOON/EVENING...20/30
PERCENT DURING THE EARLY MORNING HOURS) APPEAR WARRANTED THROUGH THE
PERIOD.

THE WEAK COLD FRONT MAY BACK DOOR ITS WAY THROUGH THE AREA BY THE
END OF THE WEEKEND...POSSIBLY KNOCKING TEMPS DOWN TO NEAR...OR
SLIGHTLY BELOW CLIMO ACROSS THE NC PIEDMONT...IN ADDITION TO
PROVIDING A FOCUS FOR INITIATION OF AFTERNOON/EVENING SHOWERS AND
STORMS. OVERALL...TYPICAL EARLY SUMMER WEATHER APPEARS IN STORE THIS
WEEKEND...WITH PERHAPS SLIGHTLY HIGHER COVERAGE OF CONVECTION THAN
IS TYPICAL.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 1245 PM THURSDAY...NO BIG CHANGES WERE MADE TO THE FCST IN THE
MEDIUM RANGE.

THE UPPER PATTERN WILL BE PROGRESSIVE...WITH RELATIVELY FLAT FLOW
ACRS THE ERN CONUS. THE WESTERLIES/POLAR JET WILL STAY WELL NORTH OF
THE CWFA. SO EXPECT PRIMARILY DIURNALLY-DRIVEN CONVECTION EVERY DAY
THRU LATE NEXT WEEK. THE OPERATIONAL GFS AND ECWMF DIVERGE QUITE A
BIT BY MIDWEEK...WITH THE GFS EARLIER AND DEEPER WITH A LONGWAVE
TROF ACRS THE MIDWEST TO THE GREAT LAKES. THE ECMWF KEEPS STRONGER
RIDGING ALONG THE EAST COAST. THE GFE/ECMWF ENSEMBLE MEANS WERE A
COMPROMISE AND PREFERRED BY WPC. THIS KEEPS ANY SIGNIFICANT/SYNOPTIC
FRONTAL BOUNDARIES TO OUR NORTH AND WEST THRU THURSDAY. I BLENDED
THE WPC/CONS/BCCONSALL WITH OFFICIAL...WHICH RESULTS IN ONLY SMALL
CHANGES. BEST COVERAGE OF CONVECTION WILL BE ACRS THE MTNS EACH DAY.
TEMPS WILL CONTINUE TO BE SLIGHTLY ABOVE NORMAL THRU THE MEDIUM
RANGE.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
AT KCLT...WINDS SHOULD SHIFT TO THE NW BY MID AFTN...IF NOT
SOONER...AS LOW PRESSURE DEVELOPS FURTHER S ALONG THE VA/NC COAST.
THEY WILL PREVAIL NORTHERLY INTO FRIDAY. CONVECTION ALLOWING MODELS
ARE CURRENTLY HANDLING UPSTREAM TSRA WELL AND SUPPORT PRECIP CHANCES
IN TEMPO RANGE LATE AFTN AND EARLY EVENING. ANY TSRA SHOULD BE MODT
TO HEAVY AND WELL CAPABLE OF MVFR VSBY...AND GUSTY WINDS. FOLLOWING
THE END OF CONVECTION...A VFR CLOUD DECK WILL LIKELY PERSIST AS A
WEAK BOUNDARY SAGS SWD THRU THE REGION. RESTRICTIONS FROM AM FOG NOT
LIKELY...BUT IF PROLONGED RAIN OCCURS THIS AFTN SOME PATCHY FOG
COULD DEVELOP.

ELSEWHERE...SHRA/TSRA WILL CONTINUE TO DEVELOP OVER THE MTNS THIS
AFTN...WITH ADDITIONAL ACTIVITY POSSIBLY MOVING IN FROM EAST TN
LATER BENEATH A WEAK SHORTWAVE. CHANCES ARE BEST OVER THE MTNS AND
ADJACENT FOOTHILLS...SO TEMPO TSRA INCLUDED AS AT KCLT. ELSEWHERE
VCTS LOOKS SUFFICIENT. MTN VALLEY FOG EXPECTED AT DAYBREAK
PARTICULARLY IF TSRA AFFECT THOSE AREAS THIS AFTN. GUIDANCE ALSO
HITS KAND WITH FOG. WINDS WILL GENERALLY BECOME NORTHERLY THIS AFTN
AND CONTINUE TO PREVAIL NLY THRU 18Z FRI...IF THEY DO NOT GO CALM
OVERNIGHT.

OUTLOOK...ISOLATED TO SCATTERED AFTERNOON AND EVENING THUNDERSTORMS
ARE EXPECTED THROUGH THE REMAINDER OF THE WEEK...WITH THE GREATEST
COVERAGE ACROSS THE MTNS. RESTRICTIONS MAY OCCUR DURING TSRA AND
ALSO IN THE MTN VALLEYS EACH MORNING WHERE LOW CLOUDS AND FOG MAY
FORM OVER AREAS OF RECENT RAINFALL.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH  95%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH  83%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH  95%     HIGH  95%

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...ARK
NEAR TERM...WIMBERLEY
SHORT TERM...JDL
LONG TERM...ARK
AVIATION...WIMBERLEY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
606 AM EDT THU JUN 19 2014

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-201015-
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-
606 AM EDT THU JUN 19 2014

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 WESTERN
CAROLINAS AND NORTHEAST GEORGIA AGAIN...MAINLY THIS AFTERNOON. ALL
OF THE STORMS WILL PRODUCE FREQUENT CLOUD TO GROUND LIGHTNING AND
TORRENTIAL RAIN. THE ATMOSPHERE IS EXPECTED TO BECOME MODERATELY
UNSTABLE THIS AFTERNOON...WHICH SHOULD ALLOW FOR SEVERAL OF THE
STORMS TO BECOME SEVERE WITH LARGE HAIL AND DAMAGING WIND GUSTS.
WESTERN NORTH CAROLINA WILL HAVE A SLIGHTLY BETTER LIKELIHOOD OF
SEVERE WEATHER. THE STORMS SHOULD WEAKEN AND DIMINISH THIS
EVENING.

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

..FRIDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.
..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.

.SPOTTER INFORMATION STATEMENT...

NONE.

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