Severe Thunderstorm Warning 90, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1029 AM EDT FRI MAY 28 2010

.SYNOPSIS...
A WEAK COLD FRONT WILL SLOWLY APPROACH FROM THE NORTH TODAY
AND MOVE SOUTHWARD THROUGH THE AREA ON SATURDAY. A STRONGER COLD
FRONT WILL APPROACH THE REGION FROM THE NORTHWEST EARLY NEXT WEEK
WITH WEAK HIGH PRESSURE MOVING IN BEHIND THE FRONT.

&&

.NEAR TERM /THROUGH TONIGHT/...
SCATTERED MORNING CONVECTION SOUTHERN AND WESTERN PORTIONS OF NC
PIEDMONT AND FOOTHILLS HAS NOT PRODUCED SIGNIFICANT WIND OR HAIL...
BUT IT INDICATES THE POTENTIAL FOR STRONG CONVECTIVE STORMS LATER
TODAY. CURRENT MESOANALYSIS PLACES HIGHEST CAPES OVER UPSTATE SC AND
JUST EAST OF MOUNTAINS IN NC. THIS HAS GENERAL AGREEMENT WITH
NUMERICAL GUIDANCE FOR THE SAME TIME.  AS LATE MORNING PROGRESSES
INTO AFTERNOON... MIXING AND WIND FLOW RESULT IN A REARRANGEMENT OF
LOW LEVEL MOISTURE SO THAT CAPES DECREASE OVER UPSTATE SC AND
INCREASE IN AN ARC ALONG SPINE OF SOUTHERN APPALACHIANS EASTWARD
ALONG NORTHERN PERIPHERY OF OUR CWA THEN SOUTHEASTWARD JUST EAST OF
CWA. SURFACE HEATING WILL PROMOTE THE DEVELOPMENT OF THUNDERSTORMS
AND CAPE WILL SUPPLY FUEL FOR STRONG UPDRAFTS. WEAK UPSLOPE FLOW
APPEARS LIKELY TO CONTRIBUTE TO FAIRLY WIDESPREAD COVERAGE OVER
HIGHER TERRAIN. SURFACE FEATURES DIFFICULT TO PIN DOWN... BUT THERE
IS STILL EVIDENCE OF WEAK NORTH-SOUTH BOUNDARY JUST TO EAST OF CWA.
BOUNDARY COULD MOVE INTO EASTERN CWA AS MID-ATLANTIC SURFACE HIGH
PRESSURE SYSTEM DRIFTS SOUTHEASTWARD. SOUTHEAST/ONSHORE SURFACE FLOW
WIL RESULT IN POOLING OF DEW POINTS IN THE VICINITY OF BOUNDARY
WHICH WILL CONTRIBUTE TO HIGHER CAPES. MID AND UPPER LEVEL RIDGE
RIGHT OVER THE AREA... SO WINDS ALOFT WILL BE VERY LIGHT.
MULTICELLULAR SEVERE CONVECTION PRODUCING DOWNBURSTS AND HAIL APPEARS
QUITE POSSIBLE BUT LACK OF STRONG WINDS AND SHEAR SHOULD LIMIT
POTENTIAL FOR MORE ORGANIZED CONVECTIVE SYSTEMS. ANOTHER OUTCOME OF
AFTERNOON AND EVENING CONVECTION WILL BE POTENTIAL FOR LOCALLY HEAVY
RAIN IN SLOWLY MOVING STORMS... ESPECIALLY OVER OR NEAR MOUNTAINS
WHERE UPSLOPE WILL AUGMENT CONVERGENCE AND VERTICAL MOTION.

PREVIOUS DISCUSSION APPLICABLE TO TONIGHT...
CONVECTION SHOULD BE MAINLY DIURNAL TONIGHT AS INSTABILITY WEAKENS
WITH COOLING AND MID/UPPER SUPPORT WANES AS WEAK RIDGING BUILDS IN.
CANNOT RULE OUT LINGERING SHOWERS OR STORMS THO. ANY SEVERE OR
FLOODING THREAT SHOULD END DURING THE EVENING AS WELL. LOWS WILL BE
AROUND 5 DEGREES ABOVE NORMAL.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 315 AM FRIDAY...THE CLOSED UPPER LOW WILL CONTINUE TO SPIN SW
OF THE FA AND SLOWLY DRIFT SOUTHWARD ACROSS CENTRAL MS. THE MAIN
SURFACE FEATURE IS IN THE FORM OF A BOUNDARY THAT SINKS SOUTHWARD
ACROSS THE FA WITH DEEP LAYER MOISTURE SITUATED WEST TO EAST ACROSS
THE CAROLINAS AND INTO THE DEEP SOUTH. CONVERGENCE ALONG THIS
REMNANT BOUNDARY AS WELL AS SOME UPSLOPE FLOW WILL ALLOW FOR
SCATTERED TO NUMEROUS COVERAGE OF SHOWERS AND THUNDERSTORMS TO
DEVELOP IN THE LATE MORNING/EARLY AFTERNOON. BEST COVERAGE IS
EXPECTED TO BE IN THE SOUTHERN ESCARPMENT AREAS AND I HAVE PAINTED A
STRIPE OF LIKELY POPS THERE. ELSEWHERE...EXPECT SCATTERED CONVECTION
TO CONTINUE THROUGH THE AFTERNOON AND EVENING...EVENTUALLY FAVORING
MORE OF THE WESTERN HALF OF THE FA IN THE LATE EVENING AND
OVERNIGHT. INSTABILITY IS EXPECTED TO BE LESS ON SATURDAY THAN ON
FRIDAY WITH MORE CONSIDERABLE CLOUD COVER AND WARMER PROFILES SO A
LESSER SEVER THREAT EXISTS. STILL...A FEW STRONG TO SEVERE STORMS
WILL BE POSSIBLE WITH ISOLATED HEAVY RAINFALL IN THE WEAK STEERING
FLOW ENVIRONMENT.

ON SUNDAY...DEEP LAYER DRYING IS PROGGED ON THE NAM (THE FAVORED
MODEL SOLUTION) MAINLY ACROSS EASTERN PORTIONS OF THE FA. THE UPPER
SAVANNAH RIVER VALLEY AND THE FAR WESTERN MOUNTAINS WILL BE CLOSE TO
THE EASTERN EXTENT OF THE DEEPER MOISTURE AND AS SUCH WILL CARRY
HIGHER POPS DURING THE AFTERNOON AND EVENING. THROUGH SUNDAY
NIGHT...THE UPPER LOW WILL GRADUALLY WEAKEN AND BEGIN TO SLOWLY
SHIFT EASTWARD OPENING UP AS A BAGGY TROF AROUND 12Z MONDAY.

TEMPERATURES ON SATURDAY WILL BE FAIRLY CLOSE TO NORMAL AS MOSTLY
CLOUDY SKIES REDUCE INSOLATION AND WORK TO KEEP TEMPS DOWN IN THE
VICINITY OF THE BOUNDARY. BY SUNDAY...LESS EXTENSIVE CLOUD COVER AND
INCREASED LOW LEVEL THICKNESSES ALLOW TEMPS TO WARM BACK INTO THE
MID AND UPPER 80S OUTSIDE THE MOUNTAINS.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 315 AM FRIDAY...LITTLE CHANGE WAS MADE TO THE GOING FORECAST.
BAGGY TROF FROM THE UPPER LOW OVER THE DEEP SOUTH WILL PERSIST
THROUGH ABOUT TUESDAY BEFORE FINALLY PUSHING EAST OF THE FA. THE
UPPER FLOW BRIEFLY TAKES ON A ANTICYCLONIC CURVATURE BEFORE THE NEXT
TROF BEGINS TO MOVE ACROSS THE DEEP SOUTH AND TOWARDS THE FA LATE IN
THE PERIOD. AT THE SURFACE...ONE FRONT WILL MOVE INTO THE SOUTHERN
APPALACHIANS FROM THE WEST ON TUESDAY...WASH OUT ACROSS THE REGION
ON WEDNESDAY...WITH INCREASING MOISTURE AND RETURN FLOW SETTING UP
OUT AHEAD OF THE NEXT AND MORE SIGNIFICANT BOUNDARY APPROACHING
THURSDAY AND THURSDAY NIGHT. THEREFORE...THE FORECAST REFLECTS ABOVE
NORMAL TEMPERATURES WITH DIURNAL SLIGHT CHANCE TO CHANCE POPS FOR
CONVECTION EACH AFTERNOON AND EVENING.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
AT KCLT...LIGHT NORTHEAST WINDS WITH SCT LOW VFR CLOUD AND BKN CI
EXPECTED THRU THE MORNING. WINDS LESS THAN 8 KTS WILL EVENTUALLY
VEER TO S FRIDAY AFTERNOON AS VFR LVL CU CIGS DEVELOP. INCREASED
CHANCES FOR LATE DAY TSTMS WILL EXIST ON FRIDAY AND CONTINUE THRU
THE EVENING. WINDS BECOME SE BY LATE AFTERNOON.

ELSEWHERE...LIGHT NORTHEAST WINDS WITH SCT LOW VFR CLOUD AND BKN CI
EXPECTED THRU THE MORNING. SCATTERED TO WIDESPREAD SHOWERS AND
TSTMS ARE EXPECTED THIS AFTERNOON AND CONTINUE INTO THE EVENING.
WINDS BECOME SLY FOR THE AFTERNOON THEN SE TO NE BY LATE AFTERNOON
OR DURING THE EVENING.

OUTLOOK...A COLD FRONT WILL REMAIN OVER THE AREA ON SAT AND WITH A
MOIST UPGLIDE FLOW EXPECT SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS AGAIN SAT AFTERNOON/EVENING. MVFR/IFR RESTRICTIONS IN
EITHER SHOWERS/STRATUS/FOG WILL CONTINUE INTO SUNDAY MORNING...WITH
IMPROVING CONDITIONS SUNDAY AFTERNOON.

&&

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

&&

SYNOPSIS...JPT
NEAR TERM...LGL/RWH
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...RWH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1040 AM EDT FRI MAY 28 2010

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-291445-
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-
1040 AM EDT FRI MAY 28 2010

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

.DAY ONE...TODAY AND TONIGHT.

THUNDERSTORM COVERAGE WILL INCREASE ACROSS THE REGION THIS
AFTERNOON. SOME THUNDERSTORMS MAY BECOME SEVERE...PRODUCING LARGE
HAIL AND DAMAGING WIND GUSTS DURING THE AFTERNOON AND TONIGHT.
SOME OF THE THUNDERSTORMS COULD ALSO PRODUCE VERY HEAVY
RAINFALL... RESULTING IN LOCALIZED FLOODING.

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

MORE THUNDERSTORMS ARE EXPECTED ACROSS THE AREA ON SATURDAY.
THOUGH THE THREAT OF SEVERE THUNDERSTORMS IS LESS THAN ON
FRIDAY...A COUPLE OF THESE STORMS COULD BECOME STRONG ENOUGH TO
PRODUCE LARGE HAIL AND DAMAGING WIND GUSTS.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...TORNADOES OR FLASH FLOODING TO OUR OFFICE.

LGL

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
844 AM EDT FRI MAY 28 2010

NCZ068-506-508-281330-
CLEVELAND-EASTERN MCDOWELL-GREATER RUTHERFORD-
844 AM EDT FRI MAY 28 2010

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN RUTHERFORD...
NORTHWESTERN CLEVELAND AND SOUTHEASTERN MCDOWELL COUNTIES THROUGH 930
AM EDT...

AT 836 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR LAWNDALE...OR 11 MILES NORTH OF SHELBY...
MOVING WEST AT 15 MPH.

* OTHER LOCATIONS AFFECTED INCLUDE BUT ARE NOT LIMITED TO BOSTIC...
  THERMAL CITY...SUNSHINE...SPINDALE...RUTHERFORDTON...FERO...
  POLKVILLE...KINGSTOWN AND CASAR.

CLOUD TO GROUND LIGHTNING...PEA SIZE HAIL...AND WIND GUSTS UP TO 40
MPH ARE EXPECTED WITH THIS STORM.

LAT...LON 3554 8157 3536 8158 3534 8207 3556 8206
      3559 8203

JPT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1042 AM EDT FRI MAY 28 2010

NCZ049-050-505-281515-
MCDOWELL MOUNTAINS-MITCHELL-YANCEY-
1042 AM EDT FRI MAY 28 2010

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL MCDOWELL...SOUTHEASTERN
MITCHELL AND SOUTHEASTERN YANCEY COUNTIES THROUGH 1115 AM EDT...

AT 1036 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 4 MILES SOUTHWEST OF MARION...MOVING NORTHWEST AT
10 MPH.

* OTHER LOCATIONS AFFECTED INCLUDE BUT ARE NOT LIMITED TO WOODLAWN...
  OLD FORT...SPRUCE PINE...MOUNT MITCHELL STATE PARK...CELO AND
  BUSICK.

DANGEROUS CLOUD TO GROUND LIGHTNING...PEA SIZE HAIL...AND WIND GUSTS
OF 30 TO 40 MPH ARE EXPECTED WITH THIS STORM.

LAT...LON 3596 8207 3574 8198 3570 8204 3569 8204
      3566 8205 3562 8217 3586 8233

JPT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1128 AM EDT FRI MAY 28 2010

NCZ503>505-281600-
BURKE MOUNTAINS-GREATER BURKE-MCDOWELL MOUNTAINS-
1128 AM EDT FRI MAY 28 2010

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN MCDOWELL AND WESTERN
BURKE COUNTIES THROUGH NOON EDT...

AT 1126 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR MORGANTON...MOVING NORTHWEST AT 15 MPH.

* OTHER LOCATIONS AFFECTED INCLUDE BUT ARE NOT LIMITED TO TABLE
  ROCK...MORGANTON...GLEN ALPINE...WOODLAWN AND ASHFORD.

SMALL HAIL...AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS
STORM.

LAT...LON 3581 8164 3565 8175 3569 8186 3572 8187
      3577 8194 3574 8199 3578 8208 3587 8202
      3587 8199 3591 8199 3591 8195 3594 8196
      3597 8194

JPT