Severe Thunderstorm Warning 394, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
251 PM EDT TUE AUG 5 2008

.SYNOPSIS...
THE UPPER LEVEL RIDGE WILL BEGIN TO BREAK DOWN IN MID WEEK...BUT
HOLD ON LONG ENOUGH TO BRING ONE MORE VERY HOT DAY ON WEDNESDAY.  A
WEAK COLD FRONT WILL MOVE SLOWLY SOUTH ACROSS THE AREA WEDNESDAY
NIGHT AND THURSDAY...FOLLOWED BY A SECOND COLD FRONT TO START THE
WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
THIS AFTERNOON...A WEAKENING LINE OF TSRA OVER EASTERN TN WILL TRACK
SE TOWARD THE NRN MTNS AND FOOTHILLS OF NORTH CAROLINA. THESE STORMS
DEVELOPED ALONG AN OLD GUST FRONT...LIFT ASSOCIATED WITH THE
BOUNDARY SHOULD WASH OUT AS IT MOVES INTO HIGHER TERRAIN.
HOWEVER...A FEW CELLS COULD EITHER TRACK OR DEVELOP OVER THE NRN
TIER OF THE CWA LATE THIS AFTERNOON INTO THE EARLY EVENING. I WILL
CONTINUE TO ADVERTISE SCHC POPS ACROSS THE NRN MTNS EAST INTO THE
FOOTHILLS. ANY COVERAGE OF DEEP CONVECTION SHOULD RAPIDLY DECREASE
AFTER SUNSET. TONIGHT...THICKENING DEBRIS CLOUDS WILL BUILD OVER THE
FORECAST AREA...RESULTING IN SLOWER COOLING THAN OBSERVED LATE
NIGHT. I WILL FORECAST LOW TEMPERATURES TONIGHT A DEGREE OR TWO
ABOVE VALUES OBSERVED THIS MORNING.

BY SUNRISE...MCS/S SHOULD BE ONGOING ACROSS THE LOWER OHIO RIVER
VALLEY. MCS ACTIVITY WILL SHIFT SOUTHEAST THROUGH THE REST OF THE
MORNING...POSSIBLY REACHING THE NC LINE BETWEEN 15-18Z. EAST OF THE
MTNS...TEMPERATURES SHOULD WARM INTO THE MID TO U90S OVER DEWPOINTS
IN THE MID 60S. AFTERNOON CAPE VALUES WILL LIKELY RANGE FROM
1000-2000 J/KG DURING THE AFTERNOON AND EARLY EVENING. CIN VALUES
WILL DECREASE TO NEAR ZERO BETWEEN 18-21Z...PROMOTING THE INITIATION
OF TSRA EAST OF THE MTNS AFTER 18Z. FORECAST SOUNDINGS INDICATE THAT
ADEQUATE WIND SHEAR WILL BE PRESENT WED AFTERNOON TO SUPPORT
MULTICELL STORM STRUCTURES...ESPECIALLY OVER THE I-40 CORRIDOR OF
NC. I WILL FORECAST HIGH CHC TO LIKELY POPS ACROSS THE NRN MTNS TO
30-40 PERCENT SOUTH AND EAST. SEVERAL STORMS MAY PRODUCE STRONG TO
SEVERE WINDS WITH LARGE HAIL.

FORECAST HIGH TEMPERATURES FOR WEDS MAY CHALLENGE THE RECORD HIGH
TEMPERATURES AT KGSP AND KAVL. SEE CLIMATE SECTION BELOW.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
AS OF 230 PM TUESDAY...UPPER LEVEL HEIGHTS WILL CONTINUE TO FALL
STEADILY ACROSS THE REGION WED NIGHT THROUGH THURSDAY. THE BEST DEEP
LAYER DIFFERENTIAL POSITIVE VORTICITY ADVECTION IN THE DEEPENING
TROUGH WILL ARRIVE ACROSS THE SOUTHERN APPALACHIANS BY 21Z THU AFTN.
THIS FORCING WILL COINCIDE WITH UPPER DIVERGENCE NEAR THE RIGHT
ENTRANCE REGION OF THE JETLET PUSHING SOUTH...AND CONTINUED LOW
LEVEL CONVERGENCE IN THE VICINITY OF THE FRONTAL ZONE DRAPED ACROSS
THE REGION. CLOUDS MAY BE MORE ABUNDANT TO LIMIT HEATING SOMEWHAT
THU AFTERNOON...BUT 700 TO 500 MB WIND FLOW INCREASING TO BETWEEN 30
AND 40 KT WILL KEEP THE SLIGHT RISK OF SEVERE THUNDERSTORMS GOING
THROUGH THE PERIOD.

UPPER DIVERGENCE WILL LINGER INTO FRIDAY AS ADDITIONAL SHORTWAVES
MOVE ACROSS THE REGION THROUGH MIDDAY. DEEPER MOISTURE APPEARS TO
LINGER SOMEWHAT AS THE FRONTAL ZONE CONTINUES TO SLIDE SOUTH...SO
THE FORCING MAY PERMIT SCATTERED CONVECTIVE CONVERAGE TO CONTINUE
THURSDAY NIGHT...AND POSSIBLY LINGER INTO FRIDAY AFTERNOON ACROSS
THE SOUTHEAST PIEDMONT.

THE GFS MAY BE OVERDONE WITH THE AMPLITUDE OF THE ERN TROUGH ON
SATURDAY...BUT A GENERAL LONGWAVE TROUGH PATTERN SHOULD PERSIST INTO
THE WEEKEND. PROFILES WILL DRY OUT AND ANY POPS SHOULD BE CONFINED
TO ISOLATED DIURNAL CONVECTION GIVEN LIMITED INSTABILITY AND THE
LACK OF ANY APPARENT STRONG TRIGGERS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM TUESDAY...THE ECMWF CONTINUES TO BE THE HPC PREFERRED
MODEL FOR THE EXTENDED RANGE. THE GFS MODEL RUNS HAVE BEEN VERY
INCONSISTENT...LEADING TO A FORECAST BASED PRIMARILY ON THE ECMWF.
STARTING SUNDAY...THE FORECAST TENDS TO BE FAIRLY DRY WITH A WEAK
UPPER LEVEL RIDGE BEGINNING TO BUILD INTO THE AREA ON SUNDAY AND
THEN WEAKENING THROUGH THE BEGINNING OF THE WEEK. THIS WILL ALLOW
ANOTHER WEAK COLD FRONT TO APPROACH THE AREA FROM THE NORTH ON
TUESDAY. MOISTURE WILL BEGIN SURGING INTO THE AREA BY LATE DAY
MONDAY WHICH WILL INCREASE CLOUD COVER FOR THE REMAINDER OF THE
PERIOD. A COMBINATION OF MOISTURE AND THIS WEAK COLD FRONT WILL
BRING INCREASED CHANCES FOR PRECIPITATION MAINLY FOR THE MOUNTAINS
WITH A SLIGHT CHANCE LATE IN THE PERIOD FOR THE PIEDMONT OF THE
CAROLINAS. TEMPERATURES SHOULD REMAIN AT OR SLIGHTLY BELOW NORMAL
FOR THE FORECAST PERIOD.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
DEBRIS CLOUDS FROM THE OHIO RIVER VALLEY SHOULD CONTINUE TO SINK
SOUTHWARD AROUND THE EASTERN EDGE OF THE RIDGE THROUGH TONIGHT. AT
THE SFC...WEAK HIGH PRESSURE WILL REMAIN OFF TO THE SOUTHWEST WITH A LEE
TROF ACROSS THE CAROLINAS AND VIRGINA...RESULTING IN LIGHT SOUTHWEST
WINDS THROUGH 12Z WED. DEWPOINT DEPRESSIONS SHOULD REMAIN 3 DEGREES
OR GREATER OVERNIGHT...RESULTING IN LITTLE IF ANY FOG.

ON WED...A BACKDOOR COLD FRONT WILL SLIDE SOUTHWARD...POSSIBLY
REACHING THE NC/VA LINE BY WED EVENING. TSRA/SHRA WILL DEVELOP ALONG
AND AHEAD OF THE FRONT...MOVING INTO THE NC MTNS AROUND MIDDAY AND
DEVELOPING ACROSS THE FOOTHILLS AND PIEDMONT DURING THE AFTERNOON. IT
APPEARS THAT COVERAGE WILL NOT INCREASE SIGNIFICANTLY BEFORE
18Z...KEEPING THE TERMINALS DRY DURING THE AM. GUSTY NORTHWEST WINDS
MAY DEVELOP BETWEEN 16-18Z WITH DEEP MIXING AND INCREASING PRESSURE
GRADIENT.

OUTLOOK...TSTM CHANCES WILL BE ON THE INCREASE WEDNESDAY AFTERNOON
AND THURSDAY OUT AHEAD OF AN APPROACHING COLD FRONT. DRIER AIR WILL
OVERSPREAD THE REGION FRIDAY THROUGH SUNDAY.

&&

.CLIMATE...
HERE ARE THE DAILY RECORD HIGH TEMPERATURES FOR TODAY AND WEDNESDAY AND THE
YEAR IN WHICH THEY OCCURRED.

TUESDAY 8/5

GREENVILLE-SPARTANBURG  99  1954
       CHARLOTTE       100  1954
       ASHEVILLE        92  2002

WEDNESDAY 8/6

GREENVILLE-SPARTANBURG  98  2007
       CHARLOTTE       102  1956
       ASHEVILLE        90  1991

&&

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

&&

SYNOPSIS...DEO
NEAR TERM...NED
SHORT TERM...HG
LONG TERM...JS
AVIATION...NED
CLIMATE...NED

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
349 PM EDT TUE AUG 5 2008

GAZ010-017-NCZ033-048>053-058-059-062>065-501-503-505-507-509-
SCZ001>003-062000-
RABUN-HABERSHAM-AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-
GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
HENDERSON-CALDWELL MOUNTAINS-BURKE MOUNTAINS-MCDOWELL MOUNTAINS-
RUTHERFORD MOUNTAINS-POLK MOUNTAINS-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-
349 PM EDT TUE AUG 5 2008

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

AN ISOLATED THUNDERSTORM WILL BE POSSIBLE ACROSS THE MOUNTAINS
THROUGH EARLY EVENING. ANY THUNDERSTORM CAN PRODUCE DANGEROUS
CLOUD TO GROUND LIGHTNING.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

A COLD FRONT WILL SLOWLY SINK SOUTHWARD TOWARD THE REGION ON
WEDNESDAY...THEN CONTINUE TO MOVE ACROSS THE FORECAST AREA THROUGH
THURSDAY NIGHT. SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP
ACROSS THE REGION WEDNESDAY AND THURSDAY AFTERNOON AND
EVENING...WITH A FEW OF THESE STORMS BECOMING SEVERE. HAIL AS
LARGE AS PENNIES AND DAMAGING WIND GUSTS WILL BE THE PRIMARY
THREATS ASSOCIATED WITH THE STRONGEST STORMS THAT DEVELOP.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

GAZ018-026-028-029-NCZ035>037-056-057-068>072-082-502-504-506-508-
510-SCZ004>014-019-062000-
STEPHENS-FRANKLIN-HART-ELBERT-ALEXANDER-IREDELL-DAVIE-CATAWBA-ROWAN-
CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-UNION NC-
GREATER CALDWELL-GREATER BURKE-EASTERN MCDOWELL-GREATER RUTHERFORD-
EASTERN POLK-GREATER OCONEE-GREATER PICKENS-GREATER GREENVILLE-
SPARTANBURG-CHEROKEE-YORK-ANDERSON-ABBEVILLE-LAURENS-UNION SC-
CHESTER-GREENWOOD-
349 PM EDT TUE AUG 5 2008

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

HOT AND HUMID CONDITIONS WILL CONTINUE THROUGH THE LATE
AFTERNOON...WITH HEAT INDEX VALUES RISING TO BETWEEN 100 AND 103
FOR A COUPLE OF HOURS...ESPECIALLY ACROSS THE UPSTATE OF SOUTH
CAROLINA AND NORTHEAST GEORGIA.

AN ISOLATED THUNDERSTORM WILL BE POSSIBLE THROUGH EARLY
EVENING...MAINLY OVER LOCATIONS JUST EAST OF THE MOUNTAINS. THE
MAIN THREAT WITH ANY THUNDERSTORMS WOULD BE A FEW CLOUD TO GROUND
LIGHTNING STRIKES.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

HOT AND HUMID CONDITIONS ARE EXPECTED AGAIN ON WEDNESDAY AFTERNOON
WITH HEAT INDEX VALUES RISING TO THE 100 TO 105 DEGREE RANGE FOR A
COUPLE OF HOURS ACROSS PIEDMONT AREAS IN THE WESTERN CAROLINAS AND
NORTHEAST GEORGIA.

A COLD FRONT WILL SLOWLY SINK SOUTHWARD TOWARD THE REGION ON
WEDNESDAY...THEN CONTINUE TO MOVE ACROSS THE FORECAST AREA THROUGH
THURSDAY NIGHT. SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP
ACROSS THE REGION WEDNESDAY AND THURSDAY AFTERNOON AND
EVENING...WITH A FEW OF THESE STORMS BECOMING SEVERE. HAIL AS
LARGE AS PENNIES AND DAMAGING WIND GUSTS WILL BE THE PRIMARY
THREATS ASSOCIATED WITH THE STRONGEST STORMS THAT DEVELOP.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

HG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
417 PM EDT TUE AUG 5 2008

SCZ001-002-004-005-052115-
GREATER OCONEE-GREATER PICKENS-OCONEE MOUNTAINS-PICKENS MOUNTAINS-
417 PM EDT TUE AUG 5 2008

...A STRONG THUNDERSTORM WILL AFFECT EASTERN OCONEE AND SOUTHERN
PICKENS COUNTIES THROUGH 515 PM EDT...

AT 412 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR LAKE KEOWEE...OR 9 MILES NORTHEAST OF
WALHALLA...MOVING SOUTHEAST AT 7 MPH.

THIS STORM WILL BE NEAR...
  NORRIS BY 515 PM EDT.

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

KRENTZ