Severe Thunderstorm Warning 91, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
303 PM EDT FRI APR 21 2006

.SHORT TERM /TONIGHT THROUGH MONDAY/...
AREA OF ORGANIZED CONVECTION ASSOCIATED WITH LOW LEVEL CONVERGENCE
AT THE NOSE OF THE LLJ AND W/IN UPPER DIVERGENCE SOUTH OF THE UPPER
JET IS LIFTING INTO THE CENTRAL APPALACHIANS/OHIO VALLEY AS
EXPECTED. STILL EXPECT TERRAIN INFLUENCES...GENERAL WEAK ISENTROPIC
UPGLIDE...AND LOW LEVEL CONVERGENCE ALONG SURFACE TROUGH ACROSS
GEORGIA TO ALLOW FOR ISOLATED (EAST) TO NUMEROUS (WEST) SHOWERS/
STORMS TO DEVELOP THROUGH THE AFTERNOON AND EARLY EVENING.
HOWEVER...THE MAIN SHOW WILL BE LATER THIS EVENING THROUGH THE
PRE-DAWN HOURS...AS SURFACE BOUNDARY APPROACHES FROM THE TENN
VALLEY. WEAK SURFACE LOW PRESSURE DEVELOPING ALONG THIS FEATURE
ACROSS THE LOWER MISS VALLEY WILL MAXIMIZE CONVERGENCE ACROSS THE
TENN VALLEY THIS EVENING...THEN ACROSS THE NC MNTNS DURING THE
PRE-DAWN HOURS. IN FACT...THE NAM AND GFS DEPICT AN EXTENDED PERIOD
OF STRONG LOW/LEVEL CONVERGENCE/UPPER LEVEL DIVERGENCE (DEEP/STRONG
OMEGA) ACROSS THE WESTERN MOUNTAINS LATE TONIGHT. CONSIDERING PWATS
ARE 150-175 PERCENT OF NORMAL...AM CONSIDERED ABOUT THE POTENTIAL
FOR EXCESSIVE RAINFALL...AS WE EXPECT QPF IN THE 2-3 INCH RANGE
ALONG THE TENNESSEE BORDER. IF WE WERE NOT IN THE MIDDLE OF A
DROUGHT...I WOULD PROBABLY PULL THE TRIGGER...BUT CONSIDERING
ANTECEDENT CONDITIONS...WILL ALLOW THE EVENING SHIFT TO FURTHER
EVALUATE THE POTENTIAL.

FURTHER SOUTH AND EAST...IT APPEARS THE POTENTIAL FOR AN ORGANIZED
MCS TO DEVELOP ACROSS MS/AL/GA THIS AFTERNOON AND EVENING THEN MOVE
INTO OUR SOUTHWEST ZONES IS QUITE HIGH (BASED ON REGIONAL RADAR
TRENDS)...AND WILL FEATURE CATEGORICAL POPS FROM I-26 WEST ACROSS
THE UPSTATE/NE GEORGIA. AS THE FRONT MOVES ACROSS THE AREA
SATURDAY...POPS WILL DIMINISH FROM WEST TO EAST ACROSS THE CWFA.
-JDL

EXPECT ALL THE FORCING TO BE EAST OF THE FORECAST AREA BY 00Z
SUNDAY...SO THE PRECIP CHANCE WILL BE CUT WAY BACK SATURDAY EVENING
WEST OF I-77. WILL RETAIN A LOW CHANCE I-77 AND EAST JUST IN CASE
THE TIMING IS OFF...BUT EXPECT THE PRECIP TO BE LONG GONE BY THEN.

FROM SATURDAY NIGHT ONWARD...THE WESTERN CAROLINAS SHOULD REMAIN
UNDER A NW FLOW ALOFT WITH A SUCCESSION OF WEAK WAVES ROUNDING THE
CLOSED LOW AND DROPPING DOWN ACROSS THE REGION. THIS PATTERN IS
UNFAVORABLE TO ANY PRECIP EAST OF THE MOUNTAINS SO THE PIEDMONT WILL
BE KEPT DRY THROUGH MONDAY. OVER THE MOUNTAINS THOUGH...EXPECT
ENOUGH INSTABILITY TO SUPPORT THE DEVELOPMENT OF WIDELY SCATTERED
DIURNAL SHOWERS AND THUNDERSTORMS SUNDAY AND MONDAY. THERE IS THE
DISTINCT POSSIBILITY THAT UPSTREAM MCS FORMATION COULD IMPACT THE
MOUNTAINS...PARTICULARLY SUNDAY EVENING...BUT FOR NOW WILL KEEP POP
IN THE SLIGHT CHANCE RANGE. FAVORED THE WARMER MET GUIDANCE FOR MIN
TEMPS WITH THE POSSIBILITY OF MORE CLOUDS. -PM

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
THE MEDIUM RANGE PERIOD SHOULD START OUT WITH A NEARLY ZONAL
FLOW...WHICH WILL TRANSITION TO A BROAD TROFFINESS OVER THE
CAROLINAS FOR LATE TUESDAY AND INTO THURSDAY. SHORT WAVES MOVING
ALONG IN THE FLOW WILL HELP TO BRING A SLOW MOVING COLD FRONT ACROSS
THE REGION...PROBABLY TUESDAY NIGHT OR EARLY WEDNESDAY. GIVEN THIS
SCENARIO...THE ONGOING FORECAST FOR THIS TIME PERIOD STILL LOOKS
REASONABLE...AND THE POP WILL ACTUALLY BE BUMPED UP TO LIKELY ALONG
THE TN BORDER FOR TUESDAY. THE INCREASED CLOUD COVER SUPPORTS A
WARMER MIN TEMP TUESDAY MORNING...SO THIS WAS NUDGED UP AS MUCH AS A
CATEGORY IN SOME SPOTS. ACTUALLY...MIN TEMPS WERE RAISED A FEW
DEGREES EACH NIGHT BASED ON THE GUIDANCE TREND...GIVEN AN UPPER TROF
THAT IS NOT AS DEEP. THE PRECIP CHANCE WILL BE KEPT TUESDAY NIGHT
AND WEDNESDAY...AND WILL BE BACKED OFF WEDNESDAY NIGHT AS THE FRONT
SINKS WELL SOUTH OF THE FORECAST AREA. THURSDAY AND FRIDAY LOOK DRY
AS HIGH PRESSURE BUILDS IN FROM THE WEST WITH WEAK UPPER RIDGING
UPSTREAM.

&&

.AVIATION...
MAIN CONCERN FOR THIS PERIOD IS WITH CHANCES FOR CONVECTION
AFFECTING THE TERMINALS THIS EVENING AND OVERNIGHT. EXPECT THE
CHANCES FOR ORGANIZED CONVECTION TO BE QUITE LOW ACROSS THE REGION
THIS AFTERNOON AND EARLY THIS EVENING. THERE WILL CERTAINLY BE
SCATTERED (PIEDMONT) TO NUMEROUS (MNTNS) SHOWERS AND STORMS
ABOUT... BUT DETERMINING WHEN/WHERE THESE MAY AFFECT ONE OF THE
TERMINALS IS NEXT TO IMPOSSIBLE AT THIS POINT. ORGANIZED
CONVECTION WILL BE MORE LIKELY TONIGHT...AS FRONTAL BOUNDARY
APPROACHES THE AREA. WE HAVE INTRODUCED CATEGORICAL CONVECTION TO
THE TERMINALS GENERALLY AFTER MIDNIGHT ACROSS THE WEST...AND
CLOSER TO SUNRISE ACROSS THE EAST. MVFR CIGS AND AT LEAST MVFR FOG
WILL LIKELY ACCOMPANY BURSTS OF CONVECTIVE PRECIP. DEEP CONVECTIVE
CHANCES WILL CONTINUE INTO THE EARLY AFTERNOON HOURS
TOMORROW...ESPECIALLY ACROSS THE PIEDMONT.

&&

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

SHORT TERM...JDL/PM
LONG TERM...MOORE
AVIATION...JDL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
331 AM EDT FRI APR 21 2006

GAZ010-017-018-026-028-029-NCZ033>037-048>059-062>072-082-
SCZ001>014-019-220745-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-CALDWELL-
ALEXANDER-IREDELL-DAVIE-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-
BUNCOMBE-MCDOWELL-BURKE-CATAWBA-ROWAN-GRAHAM-NORTHERN JACKSON-
MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-POLK-RUTHERFORD-
CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-UNION NC-
OCONEE MOUNTAINS-PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-
GREATER OCONEE-GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-
CHEROKEE-YORK-ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-
GREENWOOD-
331 AM EDT FRI APR 21 2006

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

.DAY ONE...TODAY AND TONIGHT

LOOK FOR THUNDERSTORMS IN THE AREA TODAY AND TONIGHT. SOME STORMS
COULD BECOME SEVERE...THE MAIN THREAT BEING LARGE HAIL AND WIND.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THUNDERSTORMS ARE EXPECTED TO CONTINUE ACROSS THE AREA SATURDAY INTO
SATURDAY EVENING. THERE IS ANOTHER CHANCE OF THUNDERSTORMS
WEDNESDAY AND WEDNESDAY NIGHT. SOME STORMS COULD BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATER TODAY.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
631 PM EDT FRI APR 21 2006

SCZ010-212330-
ANDERSON-
INCLUDING THE CITY OF...ANDERSON
631 PM EDT FRI APR 21 2006

...STRONG THUNDERSTORM TO AFFECT ANDERSON COUNTY THROUGH 730 PM...

AT 631 PM...NATIONAL WEATHER SERVICE RADAR INDICATED A STRONG
THUNDERSTORM JUST SOUTH OF LAKE HARTWELL ALONG THE BORDER BETWEEN
ANDERSON AND HART COUNTIES. THIS THUNDERSTORM WAS MOVING NORTHEAST
AT 20 MPH...AND WILL AFFECT STARR BY 645 PM...AND ANDERSON AROUND
700 PM. EXPECT TORRENTIAL DOWNPOURS AND FREQUENT LIGHTNING...AND
PEA SIZE HAIL WILL ALSO BE POSSIBLE.

HG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
648 PM EDT FRI APR 21 2006

GAZ029-212330-
ELBERT-
INCLUDING THE CITY OF...ELBERTON
648 PM EDT FRI APR 21 2006

...STRONG THUNDERSTORM TO AFFECT ELBERT COUNTY THROUGH 730 PM...

AT 648 PM...NATIONAL WEATHER SERVICE RADAR INDICATED A STRONG
THUNDERSTORM 2 MILES WEST OF ELBERTON...MOVING NORTHEAST AT 20
MPH. THIS THUNDERSTORM WILL AFFECT LOCATIONS FROM THE NORTH SIDE
OF ELBERTON TO NORTH OF RUCKERSVILLE THROUGH 730 PM. THIS
THUNDERSTORM WILL PRODUCE TORRENTIAL DOWNPOURS...FREQUENT
LIGHTNING...AND POSSIBLY PEA SIZE HAIL. FREQUENT RISES ALONG DOVE
CREEK AND BEAVERDAM CREEK CAN ALSO BE EXPECTED.

HG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
707 PM EDT FRI APR 21 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0701 PM     HAIL             4 W ANDERSON            34.52N 82.72W
04/21/2006  E0.88 INCH       ANDERSON           SC   AMATEUR RADIO

&&

PTANNER

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
715 PM EDT FRI APR 21 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0714 PM     HAIL             ANDERSON                34.52N 82.65W
04/21/2006  E1.25 INCH       ANDERSON           SC   AMATEUR RADIO

            SOUTH SIDE OF ANDERSON.

&&

CSH

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