Severe Thunderstorm Warning 170, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1104 AM EST WED NOV 24 2004

.SHORT TERM (REST OF TODAY)...
UPDATE WILL BE ISSUED SHORTLY TO COVER TORNADO WATCH 901 UNTIL 22Z.
NORTHERN SECTION OF THE SQUALL LINE SHOULD MOVE INTO NE GA AND THE
UPSTATE BY 1130AM. CAPES OVER NE GA AND THE UPSTATE REMAIN RATHER
WEAK WITH LAPS ESTIMATING VALUES OF 50-150 J/KG. HOWEVER...WIND
FIELDS ARE BECOMING MORE FAVORABLE AS HELICITY VALUES HAVE GRADUALLY
IMPROVED THIS MORNING...LATEST VAD WIND PROFILE HELICITIES ARE
AROUND 100 M2/S2 0-3 KM. WILL EXPECT CONDITIONS TO DESTABILIZE THIS
AFTERNOON OVER THE UPSTATE AS RICHER DWPTS AND TEMPS DEVELOP...CAPES
MAY REACH 500 J/KG. WILL EXPECT THE SEVERE THREAT TO REMAIN IN THE
CURRENT WATCH ARE TODAY...POSSIBLY EXPANDING INTO THE NC PIEDMONT
THIS AFTERNOON.

TEMPS OFF TO A SLOW START AND WILL UPDATE TEMPS CLOSER TO FLP
GUIDANCE. WILL UPDATE MAINLY TO CLEAN UP WORDING AND SUPPORT THE
WATCH.
&&

.PREVIOUS DISCUSSION...
THE FOLLOWING WAS ORIGINALLY ISSUED AT 635 AM EST WED NOV 24 2004

SHORT TERM (REST OF TODAY)...
BAND OF WAA RNFL HAS REALLY OVERTURNED THE LOWER LAYERS ACRS THE
NC FTHLS/PIEDMONT WITH JUST ABOUT EVERY 11Z MTR WELL ABOVE 1/4SM...
MOSTLY IN THE 2-3SM RANGE...SO WILL CANCEL DENSE FOG ADVISORY.

ALSO HAVE REFINED HEAVY CONVECTIVE RAIN THREAT IN GRIDS TODAY...
WITH HEAVY PCPN AXIS ACRS THE SW NC/NE GA MTNS EARLY THIS MORNING
SHIFTING GRADUALLY SE INTO THE UPSTATE/GA PIEDMONT AS THE MORNING
WEARS ON AND INTO THE AFTERNOON.

THE FOLLOWING WAS ORIGINALLY ISSUED AT 245 AM EST WED NOV 24 2004

SHORT TERM (TODAY THROUGH THURSDAY)...
SFC BNDRY TOOK A DIP TO THE SOUTHWEST YESTERDAY EVENING WITH WEAK
IN-SITU WEDGE IN PLACE...MAINLY THE RESULT OF FALLING PRESSURES TO
THE SW OF THE FRONT. AS OF 07Z...FRONT LOOKS TO BE BETWEEN GSP-AND
AND SHOULD GRADUALLY LIFT NORTH LATER THIS MORNING. INCREASE IN
WAA FLOW ABOVE THIS SFC FRONT HAS RESULTED IN AREAS OF DENSE FOG.
EVEN THOUGH DENSE FOG EXTENDS LOCALLY TO AROUND GSP METRO...WILL
LEAVE ADVISORY FOR NC FTHLS/PIEDMONT AS IS FOR NOW.

THROUGHOUT THE MORNING...MAIN SOURCE OF LIFT WILL BE FROM
AFOREMENTIONED WAA...SO WOULD EXPECT A CONTINUED INCREASE IN WAA
SHOWER CVRG. SLUG OF DEEP OMEGA AND MOISTURE STILL PROGGED TO
DRAMATICALLY INCREASE ACRS THE CWFA THIS AFTERNOON ALL WITHIN BROAD
DIFFLUENT FLOW ESE OF STRONG 130+ KT UPPER JET AXIS. ETA MODEL
TIMEHEIGHTS INDICATE STRONG ADVECTION OF MID-LVL LOW-THETA-E AIR
INTO THE CWFA THIS AFTERNOON... INDICATIVE OF COLD FRONT ALOFT. SO
WHAT WE ARE LOOKING AT IS THE LIKELIHOOD OF A STRONGLY FORCED SQUALL
LINE EVOLVING EASTWARD WITHIN A STRONGLY SHEARED WIND FIELD. 60+ DEG
F SFC DWPTS SHOULD SURGE NORTH ACRS THE PIEDMONT BY THIS AFTERNOON
AND EVEN THOUGH THIS WOULD EQUATE TO BEST INSTABILITY DEVELOPING
ACRS THE SOUTHEASTERN 1/2 OF THE CWFA...STRONG GRADIENT WINDS AND
HEAVY RAIN THREAT COULD TOPPLE SOME TREES IN THE MTNS. AXIS OF HIGH
PWATS AND SFC MOISTURE CONVERGENCE DOES BEND NNE TOWARD THE CWFA
TODAY...AND EVEN THOUGH PROBABILITY OF HVY RAIN SEEMS HIGH...OUTSIDE
OF THE EXTREME SW...ANTECEDENT CONDS NOT TERRIBLY THREATENING AT
THIS POINT TO CONCLUSIVE SAY A FFA WOULD BE NEEDED.

FOR TONIGHT AND THANKSGIVING DAY...WILL TAPER POPS FROM CATEGORICAL
TO CHC WEST TO EAST DURING THE EVENING HOURS AS SFC COLD FRONT
SWEEPS ACRS. LEAVING LOW CHC POPS IN THE TENNESSEE BORDER COUNTIES
WITH A PERIOD OF DEEPER RH THROUGH THURSDAY MORNING. GENERALLY
FOLLOWED MAGNITUDE OF GFS WITH RESPECT TO CAA AND PARTIAL THICKNESS
VALUES TUMBLING TO CRITICAL VALUES THURSDAY MORNING. NW FLOW
MOISTURE TO BECOME INCREASINGLY SHALLOW BY AFTERNOON ALLOWING POPS
TO FALL TO NEAR ZERO BY SUNSET.

LONG TERM (THURSDAY NIGHT THROUGH TUESDAY)...
INHERITED DRY FCST CWFA WIDE THURSDAY NIGHT STILL ON TRACK AS
MIXING RAPIDLY DIMINISHES BY 12Z FRIDAY WITH SFC RIDGE AXIS
BUILDING IN. NO CHANGES MADE PAST FRIDAY MORNING.

AVIATION...
IN SITU WEDGE HAS RESULTED IN SOLID LIFR CIGS AND VSBYS BASICALLY
ALONG AND N OF I85 THIS MORNING. CONDITIONS ARE A LITTLE MORE
VARIABLE SOUTH OF THE BNDRY. RIGHT NOW KAND IS 6SM W/A 200 FOOT CIG
FOR EXAMPLE WHILE KGSP IS 1/4SM. WL PLAY CONDITIONS TO SLOWLY
IMPROVE AS THE WARM FRONT MOVES THROUGH...THOUGH MOIST LLVLS AND
WEAK UPGLIDE THROUGH THE DAY WL LIKELY KEEP AT LEAST MVFR CIGS IN
PLACE. FAIRLY STRONG SIGN ON THE ETA THAT COLD FRONT ALOFT WILL
SWEEP ACROSS THE CWFA BETWEEN 1800 AND 0000 UTC. CONSIDERING THE
STRONG FORCING...WL GO WITH A TEMPO GROUP FOR TSRA ALL TAF SITES FOR
THE AFTN AND EARLY EVENING HOURS. CONDITIONS WL IMPROVE BEHIND THE
CONVECTION...BUT WIND SHIFT W/SFC COLD FRONT WL LIKELY NOT AFFECT
TAF SITES UNTIL AFTER 0600 UTC THU...SAVE FOR KAVL. &&
&&

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

SHORT TERM (UPDATE)...NED

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
645 AM EST WED NOV 24 2004

GAZ010-017-018-026-028-029-NCZ033>037-048>059-062>072-082-SCZ001>014-
019-251145-
ABBEVILLE SC-ALEXANDER NC-ANDERSON SC-AVERY NC-BUNCOMBE NC-BURKE NC-
CABARRUS NC-CALDWELL NC-CATAWBA NC-CHEROKEE SC-CHESTER SC-
CLEVELAND NC-DAVIE NC-ELBERT GA-FRANKLIN GA-GASTON NC-GRAHAM NC-
GREATER GREENVILLE SC-GREATER OCONEE SC-GREATER PICKENS SC-
GREENVILLE MOUNTAINS SC-GREENWOOD SC-HABERSHAM GA-HART GA-HAYWOOD NC-
HENDERSON NC-IREDELL NC-LAURENS SC-LINCOLN NC-MACON NC-MADISON NC-
MCDOWELL NC-MECKLENBURG NC-MITCHELL NC-NORTHERN JACKSON NC-
OCONEE MOUNTAINS SC-PICKENS MOUNTAINS SC-POLK NC-RABUN GA-ROWAN NC-
RUTHERFORD NC-SOUTHERN JACKSON NC-SPARTANBURG SC-STEPHENS GA-
SWAIN NC-TRANSYLVANIA NC-UNION SC-UNION NC-YANCEY NC-YORK SC-
645 AM EST WED NOV 24 2004

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

.DAY ONE...

HEAVY SHOWERS AND EMBEDDED THUNDERSTORMS WILL THREATEN THE REGION
INTO THIS EVENING. THUNDERSTORMS THIS AFTERNOON MAY CONTAIN DAMAGING
WIND GUSTS. FOR FURTHER DETAILS...PLEASE REFER TO THE LATEST SPECIAL
WEATHER STATEMENT...SPSGSP...ISSUED BY THIS OFFICE.

.DAYS TWO THROUGH SEVEN...

LINGERING SHOWERS...POSSIBLY MIXED WITH SNOW AT THE HIGHER
ELEVATIONS...MAY BE SEEN ACROSS THE TENNESSEE BORDER COUNTIES
THANKSGIVING MORNING...OTHERWISE A PARTLY CLOUDY AND WINDY HOLIDAY
IS ON TAP.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE TODAY.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
735 AM EST WED NOV 24 2004

NCZ051-058-062-241330-
GRAHAM NC-MACON NC-SWAIN NC-
735 AM EST WED NOV 24 2004

AT 730 AM EST...WEATHER RADAR SHOWED A SHORT LINE OF STRONG
THUNDERSTORMS APPROACHING GRAHAM COUNTY NORTH CAROLINA FROM THE
SOUTHWEST.  RADAR INDICATES STRONG GUSTY WINDS WITH THIS LINE...AND
THE WIND COULD GUST TO 50 MPH AS THE LINE MOVES THROUGH.  AREAS ALONG
THE SKYWAY WILL BE AFFECTED FIRST...THEN THE LINE WILL MOVE ACROSS
AREAS FROM FONTANA TO ROBBINSVILLE...AND SOUTH TO THE MACON LINE.

IF THE STORMS STRENGTHEN...A SEVERE THUNDERSTORM WARNING MAY BECOME
NECESSARY FOR SOME AREAS.  LISTEN FOR LATER STATEMENTS...AND POSSIBLY
WARNINGS.

JONES

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1101 AM EST WED NOV 24 2004

GAZ010-017-018-026-028-029-SCZ001-002-004-005-010-241800-
ANDERSON SC-ELBERT GA-FRANKLIN GA-GREATER OCONEE SC-
GREATER PICKENS SC-HABERSHAM GA-HART GA-OCONEE MOUNTAINS SC-
PICKENS MOUNTAINS SC-RABUN GA-STEPHENS GA-
1101 AM EST WED NOV 24 2004

...STRONG WIND GUSTS POSSIBLE THROUGH EARLY AFTERNOON...

A LINE OF STRONG TO SEVERE THUNDERSTORMS WILL MOVE EAST ACROSS
NORTHEAST GEORGIA THROUGH THE REMAINDER OF THE MORNING. IF THE LINE
OF STORMS HOLDS TOGETHER...THE LEADING EDGE WILL REACH HABERSHAM AND
RABUN COUNTIES BY 1130...AND THE AREA FROM HARTWELL TO CLEMSON BY
NOON AT THE LATEST. STRONG WIND GUSTS ARE POSSIBLE WITH THE LINE OF
STORMS EVEN THOUGH VERY LITTLE THUNDER IS EXPECTED.

THIS AREA REMAINS IN A TORNADO WATCH UNTIL 5 PM.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
PEOPLE IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.

MOORE