Severe Thunderstorm Warning 99, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1015 PM EDT FRI APR 21 2006

.SHORT TERM /REST OF TONIGHT/...
SCATTERED SVR TSTMS...INITIATED EARLIER THIS EVENING OVER THE
UPPER SAVANNAH RIVER VALLEY WITHIN A CONVERGENCE AND MOISTURE
AXIS CONTINUE TO MOVE OFF TO THE NORTHEAST WITHIN THE MEAN
FLOW...BUT LARGE SCALE STABILIZATION HAS RESULTED IN A RECENT
WEAKENING TREND. THE FOCUS NOW SHIFTS UPSTREAM AS LARGE SCALE
ASCENT AHEAD OF POTENT UPPER WAVE INCREASES ACRS THE WESTERN
CWFA. REGIONAL 88D LOOPS INDICATE A SOLID WALL OF SHOWERS AND
TSTMS FROM JUST WEST OF ATL AND TO NEAR TYS. EVEN THOUGH THE MOST
ROBUST TSTM ACTIVITY IS EXPECTED TO DIMINISH OVERNIGHT AS THE
LEADING EDGE OF TSTM ENCOUNTERS A LESS FAVORABLE AIRMASS...WIDESPREAD
SHOWERS AND EMBEDDED TSTMS ARE STILL ON TRACK TO OVERSPREAD THE
WESTERN CWFA AFTER MIDNIGHT...AIDED BY A STOUT WAA FLOW AND RIGHT
ENTRANCE REGION CIRCULATION OF UPPER JET. HEAVY RAIN IS A PROBABILITY
AND WILL ADD THIS WORDING TO THE NC/GA MTNS WHERE OROGRAPHIC LIFT
WILL BE ENHANCED.
&&

.PREV DISCUSSION...
 /ISSUED 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 TROFINESS 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...CSH

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
1047 PM EDT FRI APR 21 2006

NCZ036-056-069-220345-
CATAWBA-IREDELL-LINCOLN NC-
INCLUDING THE CITIES OF...HICKORY...LINCOLNTON...STATESVILLE
1047 PM EDT FRI APR 21 2006

...STRONG THUNDERSTORM TO AFFECT THE AREA FROM LINCOLNTON TO
STATESVILLE THROUGH 1145 PM...

AT 1047 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM JUST EAST OF LINCOLNTON...MOVING NORTHEAST AT
20 MPH. THIS THUNDERSTORM WILL AFFECT DENVER BY 11 PM...TERRELL
BY 1115 PM...AND TROUTMAN BY 1130 PM. EXPECT TORRENTIAL
DOWNPOURS...FREQUENT LIGHTNING...AND POSSIBLY SMALL HAIL WITH THIS
THUNDERSTORM.

HG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1053 PM EDT FRI APR 21 2006

NCZ033-048>053-058-059-062>065-220500-
AVERY-BUNCOMBE-GRAHAM-HAYWOOD-HENDERSON-MACON NC-MADISON NC-
MITCHELL NC-NORTHERN JACKSON NC-SOUTHERN JACKSON NC-SWAIN-
TRANSYLVANIA-YANCEY-
INCLUDING THE CITIES OF...ASHEVILLE...BREVARD...CHEROKEE...
FRANKLIN...HENDERSONVILLE...NEWLAND...SPRUCE PINE...SYLVA...
WAYNESVILLE
1053 PM EDT FRI APR 21 2006

...STRONG THUNDERSTORMS TO AFFECT THE NORTH CAROLINA MOUNTAINS
THROUGH THE EARLY MORNING HOURS...

A LINE OF STRONG THUNDERSTORMS WILL MOVE SLOWLY EAST INTO THE NORTH
CAROLINA MOUNTAINS DURING THE EARLY MORNING HOURS. THESE
THUNDERSTORMS WILL BEGIN TO AFFECT THE SMOKY MOUNTAINS AREA BY
MIDNIGHT...AND GRADUALLY SPREAD EAST TO THE BLUE RIDGE THROUGH 3
AM. TORRENTIAL RAINFALL AT RATES OF 1/2 TO 1 INCH PER HOUR WILL
ACCOMPANY THE THUNDERSTORMS...AS WELL AS FREQUENT LIGHTNING...AND
ISOLATED PEA SIZE HAIL.

HG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1135 PM EDT FRI APR 21 2006

SCZ007-220400-
SPARTANBURG-
INCLUDING THE CITY OF...SPARTANBURG
1135 PM EDT FRI APR 21 2006

...STRONG THUNDERSTORM TO AFFECT NORTHERN SPARTANBURG COUNTY THROUGH
MIDNIGHT...

AT 1132 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES NORTHWEST OF BOILING SPRINGS...MOVING
NORTHEAST AT 25 MPH. THIS THUNDERSTORM WILL AFFECT THE FINGERVILLE
AREA AROUND 1145 PM. EXPECT TORRENTIAL DOWNPOURS...FREQUENT
LIGHTNING AND POSSIBLY PEA SIZE HAIL WITH THIS THUNDERSTORM.

HG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1214 AM EDT SAT APR 22 2006

GAZ010-017-018-026-028-029-SCZ001-004-010-011-019-220615-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-OCONEE MOUNTAINS-
GREATER OCONEE-ANDERSON-ABBEVILLE-GREENWOOD-
INCLUDING THE CITIES OF...CLAYTON...CLARKESVILLE...TOCCOA...
HARTWELL...ELBERTON...ANDERSON...ABBEVILLE...GREENWOOD
1214 AM EDT SAT APR 22 2006

...STRONG THUNDERSTORMS MOVING INTO NORTHEAST GEORGIA AND THE
WESTERN UPSTATE...

AT 1210 AM EDT...WEATHER SERVICE RADAR INDICATED A LINE OF
THUNDERSTORMS MOVING NORTHEAST AT 35 MPH INTO NORTHEAST GEORGIA.
BETWEEN 1230 AND 115 AM THE LINE WILL MOVE ACROSS MOST OF
HABERSHAM... RABUN AND STEPHENS COUNTIES.

40 TO 50 MPH WINDS...PEA SIZED HAIL...TORRENTIAL RAIN AND
CONTINUOUS CLOUD TO GROUND LIGHTING WILL ACCOMPANY THE STRONGER
STORMS IN THE LINE. A FEW OF THE STORMS MAY BECOME SEVERE AS THEY
MOVE ACROSS THE AREA WITH LARGE HAIL AND DAMAGING WINDS.

BETWEEN 1 AND 2 AM THE LINE WILL MOVE ACROSS FRANKLIN COUNTY IN
GEORGIA AND OCONEE AND WESTERN PICKENS COUNTIES IN SOUTH CAROLINA.

MCAVOY

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1226 AM EDT SAT APR 22 2006

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

0731 PM     HAIL             1 N BELTON              34.54N 82.50W
04/21/2006  M0.25 INCH       ANDERSON           SC   PUBLIC

            GOLFBALL SIZE HAIL COVERING THE GROUND.

&&

HG

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1226 AM EDT SAT APR 22 2006

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

0731 PM     HAIL             1 N BELTON              34.54N 82.50W
04/21/2006  M1.25 INCH       ANDERSON           SC   PUBLIC

            GOLFBALL SIZE HAIL COVERING THE GROUND.

&&

HG