Severe Thunderstorm Warning 321, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
252 PM EDT MON JUL 26 2010

.SYNOPSIS...
A WEAK STATIONARY FRONT WILL LINGER OVER THE CAROLINAS THROUGH
TUESDAY...BEFORE LIFTING NORTH AS A WARM FRONT EARLY WEDNESDAY. A
COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST BY THE END OF
THE WEEK.

&&

.NEAR TERM /THROUGH TUESDAY/...
AS EXPECTED...THUNDERSTORMS ARE INITIATING OVER THE MOUNTAINS AND
WRN FOOTHILLS WHERE THERE IS GOOD MOISTURE CONVERGENCE. THIS IS THE
RESULT OF NELY UPSLOPE FLOW CAUSED BY A BACK DOOR COLD FRONT. CAPE
VALUES IN THIS AREA HAVE INCREASED TO A VERY IMPRESSIVE 3000 TO 4000
J/KG. STORMS ARE ALSO FIRING JUST SOUTH OF THE FA ALONG THE SFC
PRESSURE MINIMUM ASSOCIATED WITH THE LLVL THERMAL RIDGE. THE STORMS
OVER THE MTNS AND FOOTHILLS SHOULD PUSH TO THE SE THIS EVENING AS
OUTFLOW BNDYS MOVE INTO HOT AIRMASS OVER THE FOOTHILLS AND WESTERN
PIEDMONT. FREEZING LEVELS ARE VERY HIGH THIS AFTERNOON...BUT DAPE
VALUES ARE RUNNING BETWEEN 800-1000 J/KG. SO A FAIRLY HIGH CORE
COULD STILL PRODUCE SEVERE WINDS. WHILE STORMS WILL TEND TO MOVE AS
GOOD COLD POOLS PROPAGATE TOWARD THE THERMAL RIDGE...THERE IS STILL
A CHANCE FOR SOME TRAINING AND LOCALIZED FLASH
FLOODING...PARTICULARLY ALONG AND A LITTLE WAYS EAST OF THE BLUE
RIDGE. BLENDED TOTAL PRECIPITABLE WATER VALUES ARE WELL OVER 2
INCHES IN A SE TO NW ORIENTED BAND ACROSS THE HEART OF THE FA. IF WE
HAD MORE GROUND MOISTURE I/D ENTERTAIN A FLASH FLOOD WATCH...BUT
WITH THE DRY CONDITIONS...I DON/T THINK FLOODING WILL BE WIDESPREAD
ENOUGH TO WARRANT A WATCH. AS FOR COVERAGE...LIKELY POPS SHOULD
COVER IT FOR NOW OWING TO THE WEAK SHEAR WHICH WILL HINDER STORM
ORGANIZATION. POPS WILL BE A LITTLE OVER THE NRN NC
PIEDMONT...FURTHER FROM THE LLVL CONVERGENCE AND THE HIGHEST CAPE
VALUES. STORMS MAY STILL COMBINE INTO A LARGE COMPLEX OVER THE SRN
HALF OF THE FA IN A FEW HOURS TIME...WHICH WOULD REQUIRE A BUMP INTO
THE CATEGORICAL RANGE.

THE LIGHT NE FLOW MAY ALSO KEEP STORMS GOING WELL AFTER
SUNSET...EVEN THOUGH MOST OF THE FA WILL INITIALLY BE WORKED OVER BY
CONVECTION THIS AFTERNOON AND EARLY EVENING.

A MCV OVER MIDDLE TN WILL SLOWLY DRIFT TO THE EAST TONIGHT AND TUE.
THIS FEATURE IS CURRENTLY IS TRIGGERING INTENSE STORMS OVER MIDDLE
AND SRN TN...ONE OF THE BETTER EXAMPLES OF AN MCV INITIATING NEW
STORMS THAT I/VE SEEN IN A WHILE. THIS SHORT WAVE WILL SLOWLY CROSS
THE FA ON TUE. THIS SHOULD RESULT IN MORE SHOWERS AND TSTMS FROM THE
LATE MORNING HOURS INTO THE LATE AFTN AS THE WAVE CROSSES THE
REGION...WITH STORMS PUSHING EAST OF THE FA BY EARLY EVENING.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM MONDAY...THE DOMINATING UPPER RIDGE WILL GRADUALLY RELEASE
ITS GRIP ON THE FORECAST AREA DURING THE SHORT TERM. ALL OPERATIONAL
MODELS AND THE SREF AGREE THE RIDGE WILL SLOWLY RETROGRADE TO THE
W. THIS WILL OPEN THE DOOR FOR A WEAK COLD FRONT TO MOVE ACROSS
THE AREA ON THU. DURING THE PERIOD...STILL EXPECT CONVECTION TO
BE STRONGLY DIURNAL IN NATURE DUE WEAK UPPER SUPPORT AND STRONG
LOW LEVEL WARMING BOTH WED AND THU...AND CORRESPONDING DAYTIME
SPIKE IN CAPES. EXPECT SCATTERED TO NUMEROUS STORMS TO BE ONGOING
ACROSS THE PIEDMONT TUE EVENING...WITH PROBABLY ONLY WIDELY
SCATTERED COVERAGE LEFT OVER IN THE MOUNTAINS. EXPECT CONVECTION
TO WANE OVERNIGHT. ON WED...MODELS AGREE THAT SCATTERED TO
NUMEROUS STORMS WILL DEVELOP OVER THE MOUNTAINS BY EARLY
AFTERNOON...ADVECTING/REDEVELOPING ALONG COLD POOLS INTO THE
PIEDMONT BY LATE AFTERNOON. CONVECTION IS AGAIN EXPECTED TO WANE
OVERNIGHT...BUT DID INTRODUCE POPS LATE WED NIGHT IN THE TN BORDER
COUNTIES AS THE COLD FRONT APPROACHES. ON THU...BOTH GFS AND NAM
BRING THE WEAK COLD FRONT ACROSS THE AREA. HOWEVER...DESPITE
BETTER DIVERGENCE ALOFT...EXPECT THUNDERSTORM COVERAGE TO PROBABLY
BE SCATTERED AT BEST AS NW FLOW/DOWNSLOPE DEVELOPS LOWERING RH'S.
IN FACT THE NORTHERN UPSTATE MAY SEE A "GSP SPLIT" WITH ONLY
WIDELY SCATTERED COVERAGE. THE SOUTHERN PIEDMONT AREAS SHOULD SEE
THE BEST COVERAGE DURING THE MID TO LATE AFTERNOON. TEMPS SHOULD
REMAIN WELL ABOVE AVERAGE BOTH WED AND THU. MET GUIDANCE LOOKS
SIGNIFICANTLY TOO LOW FOR WED AS LOW LEVEL THICKESNESSES STILL
HIGH AND TEMPS SHOULD WARM QUICKLY PRIOR TO CONVECTION. UPSHOT IS
TRENDED MAX TEMPS CLOSER TO HOT MAV TEMPS. HOT TEMPS TO CONTINUE
ON THU DESPITE FRONT THANKS TO DOWNSLOPE.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 230 PM MONDAY...MEDIUM RANGE  WILL FEATURE NW UPPER FLOW
ACROSS THE REGION WITH A STRONG UPPER HIGH TO THE WEST OVER THE
SOUTH CENTRAL U.S. THE PERIOD BEGINS WITH THE FRONT TO THE SOUTH OF
THE FORECAST AREA WITH HIGH PRESSURE RIDGING OVER THE REGION FROM THE
NE. THEREFORE...EXPECT FRI TO BE A DRY DAY. THE SURFACE HIGH MOVES
EASTWARD ENOUGH ON SAT TO ALLOW WINDS TO COME AROUND TO THE SE WHICH
MAY GENERATE SOME SCATTERED MOUNTAIN CONVECTION SAT AFTERNOON
ESPECIALLY IN FAVORED UPSLOEP AREAS. THIS PATTERN EXPECTED TO HOLD
SUN AND MON WITH THE SE FLOW ADVECTING ATLANTIC MOISTURE OVER THE
AREA. THIS SHOULD FUEL WIDELY SCATTERED TO SCATTERED CONVECTION
EACH DAY FOCUSED DURING THE AFTERNOONS AND EVENINGS. STAYED CLOSE TO
HPC GUIDANCE FIELDS THROUGH THE PERIOD. TEMPS EXPECTED TO BE NEAR OR
SLIGHTLY ABOVE AVERAGE EACH DAY.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
AT KCLT...MOST OF OUR LOCAL MESOSCALE MODELS BRING WIDESPREAD
CONVECTION ACROSS THE AIRFIELD DURING THE COURSE OF THE AFTN AND
EVENING. THERE ARE STILL TIMING ISSUES...BUT BASED UPON WHERE
THUNDERSTORMS HAVE CURRENTLY DEVELOPED...WE HAVE ABOUT 3 HOURS UNTIL
OUTFLOW BOUNDARIES TRIGGER STORMS CLOSE ENOUGH TO CARRY IN AN
OBSERVATION. THEREFORE...THE CURRENT 21 TO 01 UTC TEMPO GROUP FOR
THUNDER STILL LOOKS GOOD. LATE TONIGHT THERE IS A PRETTY GOOD CHANCE
FOR IFR...OR LOWER...STRATUS TO DEVELOP. CHANCES LOOK EVEN BETTER TO
THE EAST. I/VE ADDED SCT008 TO THE TAF. IF THERE IS WIDESPREAD
RAIN...THE CHANCES WILL BE EVEN BETTER. TSTMS WILL DEVELOP ACROSS
THE REGION AGAIN IN THE AFTN...BUT THE BEST COVERAGE WILL BE JUST
OUTSIDE THE VALID PERIOD OF THE TAF.

ELSEWHERE...TSTMS ARE DEVELOPING OVER THE MTNS...AND THE OUTFLOW
BOUNDARIES WILL GRADUALLY START TO TRIGGER STORMS OUT INTO THE
FOOTHILLS AND PIEDMONT. CONVECTION SHOULD BE FAIRLY WIDESPREAD
ACROSS THERE REGION ACCORDING TO OUR MESOSCALE MODELS AND I HAVE
TEMPO THUNDER IN AT MOST SITES. AT KAVL AND KHKY STORMS WERE ALREADY
IN THE VICINITY. IT/LL TAKE ANOTHER 2 TO 3 HOURS BEFORE THEY AFFECT
THE UPSTATE SITES. LOW CLOUDS LOOK POSSIBLE OVER TOWARD KCLT...BUT
THEY LOOK LESS LIKELY AT SITES FARTHER TO THE WEST. THE EXCEPTION IS
KAVL. IF THEY SEE HEAVY RAIN...OR IS SKIES CLEAR FOR A WHILE
OVERNIGHT...THEY SHOULD REACH THEIR CROSSOVER TEMPS AND LOW CIGS
WOULD THEN BE A GOOD BET...AND PERHAPS DENSE FOG. TSTMS WILL DEVELOP
ACROSS THE REGION AGAIN TMRW AFTN.

OUTLOOK...EXPECT AT LEAST SCT SHWRS/TSTMS EACH AFTN AND EVE THRU THE
WEEK. CHANCE OF MRNG FOG WILL BE HIGHER WHERE RAIN FALLS...ESP IN
MTN VALLEYS.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

SYNOPSIS...SBK
NEAR TERM...MCAVOY
SHORT TERM...LG
LONG TERM...LG
AVIATION...MCAVOY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
331 PM EDT MON JUL 26 2010

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-271945-
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-
331 PM EDT MON JUL 26 2010

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED ACROSS THE REGION
LATE THIS AFTERNOON INTO THIS EVENING. THE MAIN THREAT FROM THESE
STORMS WILL BE HEAVY RAIN AND FREQUENT LIGHTNING. THUNDERSTORMS
WILL HAVE THE TENDENCY TO AFFECT THE SAME LOCATION MULTIPLE
TIMES...A PROCESS KNOWN AS TRAINING. WHERE THIS OCCURS...THERE
WILL BE A THREAT OF FLASH FLOODING...THOUGH THE DRY GROUND SHOULD
KEEP FLOODING FROM BECOMING WIDESPREAD ENOUGH TO WARRANT A WATCH.
THE STRONGEST STORMS WILL ALSO THE HAVE POTENTIAL TO PRODUCE
DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

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