Severe Thunderstorm Warning 204, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
529 PM EDT THU MAY 26 2011

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL PUSH A WEAKENING COLD FRONT ACROSS THE
CAROLINAS THROUGH FRIDAY MORNING. THE FRONT IS EXPECTED TO STALL AND
WASH OUT OVER THE REGION FRIDAY AFTERNOON. SUMMER LIKE WEATHER WILL
RETURN ON SATURDAY AND LINGER INTO EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
CONVECTION CONTINUES TO EXPAND IN COVERAGE ACROSS THE TENN VALLEY
AND SOUTHERN APPALACHIANS. THE DEEP LAYER SHEAR IS SUFFICIENT SUCH
THAT CONVECTION HAS BEEN DISCRETE/QUASI-SUPERCELL IN NATURE SO FAR.
HOWEVER...LOW LEVEL SHEAR REMAINS RELATIVELY WEAK...WHILE DEEP BL
MIXING HAS RESULTED IN A SUBSTANTIAL LOWERING OF SURFACE DEWPOINTS
OVER THE AREA (LCLS ARE OVER 7000 FEET). IN OTHER WORDS...DESPITE
THE STRONG DEEP LAYER SHEAR...THE TORNADO POTENTIAL...WHILE NON-
ZERO...IS VERY LOW. AS CONVECTION CONTINUES TO EXPAND...AND RESULTS
IN AN EVER INCREASING NUMBER OF SMALL OUTFLOWS...EXPECT THE
CONVECTIVE MODE TO GRADUALLY TRANSITION FROM DISCRETE CELLS TO
CLUSTERS OF STRONG-SEVERE THUNDERSTORMS PRODUCING LARGE HAIL AND
DAMAGING WINDS. FOR THE LATE AFTERNOON UPDATE...POPS WERE ADJUSTED
TO REFLECT A SLOWER ONSET/PROPAGATION OF CONVECTION...TO INCLUDE
SEVERE THUNDERSTORM WORDING IN THE FORECAST SUITE...AND TO CAPTURE
TRENDS IN OTHER FORECAST PARAMETERS.

PREVIOUS DISCUSSION...

AT 1730Z...AN UPPER TROF WILL PROGRESS ACRS THE OH/TN VLYS TONIGHT
AND LIFT NE THRU THE APPALACHIANS ON FRIDAY. THE FORCING ASSOCIATED
WITH THE APPROACH OF THE TROF WILL BE STRONGEST FROM LATE THIS AFTN
WELL INTO THE OVERNIGHT HOURS. THE GFS AND NAM AGREE ON DECENT UPPER
DIVERGE AS WELL DURING THAT TIME FRAME. SHEAR AND INSTBY WILL BE
ENUF TO SUPPORT CONVECTION THRU THE NIGHT. THERE IS CURRENTLY A SVR
TSTM WATCH TO OUR WEST...INCLUDING FOUR NC COUNTIES (SEE WCNGSP).
CONVECTION SO FAR HAS BEEN FAIRLY DISCRETE SUPERCELLS. THE MESOSCALE
MODELS SEEM TO AGREE ON THIS ACTIVITY MORPHING INTO A MULTI-CELL
LINE AS IT ENTERS THE CWA AROUND 20-22Z TIME FRAME...THEN BANDS OF
CONVECTIVE SEGMENTS WELL INTO THE OVERNIGHT. HAVE ADJUSTED POPS
ACCORDINGLY. STILL THINK ANOTHER ROW OF WATCHES WILL BE ISSUED SOME
TIME LATER THIS AFTN AS THE CONVECTION ORGANIZES. NOT SURE HOW WELL
THE CONVECTION WILL HOLD TOGETHER DURING THE WEE MORNING HOURS.
THINK CONVECTIVE THREAT WILL GRADUALLY DECREASE THRU DAYBREAK. TEMPS
OVERNIGHT WILL BE MILD WITH THE CLOUDS AND MIXING ASSOCIATED WITH
THE APPROACH OF THE COLD FRONT.

ON FRIDAY...THE FRONT STALLS OVER THE AREA...WITH PLENTY OF
LINGERING MOISTURE. UPPER SUPPORT SHOULD CONTINUE THRU 18Z AS THE
TROF PIVOTS TO NEGATIVE TILT AND SLOWS. HAVE BLENDED IN MODEL
CONSENSUS ON POPS...RESULTING IN LIKELY THRU THE AFTN (ESPECIALLY
ERN HALF OF THE CWA). SHEAR WEAKENS AND UPPER DIVERGE
DECREASES...BUT INSTBY SHUD INCREASE WITH HEATING TO 1000-1500 J/KG
ONCE AGAIN ACRS THE PIEDMONT. SO DO EXPECT SCATTERED TO NUMEROUS
TSTMS...BUT SEVERE THREAT WILL BE MODEST. NEW SPC DAY 2 OUTLOOK IS
JUST SEE TEXT. THE MET AND MAV IN DISAGREEMENT ON MAX TEMPS. WENT
WITH WARMER MAV BASED ON CONTINUITY.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 230 PM THURSDAY...THE SHORT RANGE PERIOD WILL BEGIN FRIDAY
NIGHT WITH ONGOING DIURNAL CONVECTION. EXPECT NUMEROUS COVERAGE TO
PERSIST ACROSS THE EASTERN PORTION OF THE FA FOR A FEW HOURS BEFORE
DIMINISHING IN THE LOSS OF HEATING AND MOVING FURTHER EAST. SATURDAY
WILL SEE THE TRANSITION PERIOD BETWEEN THE DEPARTING REMNANT UPPER
TROF AND RIDGE BEGINNING TO BUILD IN FROM THE SW. EXPECT STILL
MODERATE INSTABILITY TO DEVELOP ACROSS AREAS TO THE SOUTH AND EAST.
THERE WILL BE LESS CONVECTIVE INHIBITION FURTHER TO THE EAST IN THE
BETTER INSTABILITY BUT WITH WEAK WIND PROFILES THROUGH THE
COLUMN...COVERAGE WILL BE ISOLATED AT BEST. ACROSS THE
MOUNTAINS...MODEL SOUNDING SHOW A MORE PROMINENT INVERSION AND CAP
AT AROUND 700 MB...BUT SOME SOUTHERLY UPSLOPE FLOW SHOULD HELP KICK
OFF MORE SCATTERED RIDGE TOP CONVECTION. SEVERE THREAT WILL BE
MINIMAL AT BEST WITH HIGH FREEZING LEVELS...BUT DRY AIR ALOFT COULD
HELP PRODUCE A DAMAGING WIND GUST OR TWO. ANY LINGERING SHOWERS AND
STORMS WILL DISSIPATE QUICKLY AFTER SUNSET.

INTO SUNDAY...THE THE RIDGE ALOFT WILL QUICKLY ASSERT ITSELF OVER
THE SOUTHEAST WITH A VERY PROMINENT UPPER ANTICYCLONE DEVELOPING
OVER THE SOUTHERN APPALACHIANS. CONVECTION WILL BECOME EVEN MORE
LIMITED AND WE WILL ONLY CARRY SLIGHT CHANCES ALONG THE ESCARPMENT
AND THE RIDGE TOPS FOR THE NC MOUNTAINS. TEMPS WILL RUN ABOUT 6
DEGREES ABOVE NORMAL ON SATURDAY AND WILL INCREASE INTO SUNDAY WITH
THE STRENGTHENING UPPER RIDGE. SUNDAY HIGHS WILL INCREASE BACK INTO
THE UPPER 80S OUTSIDE THE MOUNTAINS...WITH MID 80S EXPECTED IN THE
MOUNTAIN VALLEYS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 200 PM THURSDAY...THE MEDIUM RANGE GUIDANCE IS IN AGREEMENT
THAT AN UPPER LEVEL ANTICYCLONE WILL DOMINATE THE WEATHER OVER THE
SOUTHERN APPALACHIANS AND WESTERN CAROLINAS THROUGH MIDWEEK. THE
UPPER HIGH IS FORECAST TO RETROGRADE INTO THE SOUTHERN PLAINS BY LATE
NEXT WEEK WHICH PAVES THE WAY FOR A BACKDOOR COLD FRONT TO MOVE
THROUGH IN THE WED NIGHT THU TIMEFRAME. MON THROUGH WED WILL FEATURE
GENERALLY CLEAR CONDITIONS...HOT TEMPERATURES AND SUPPRESSED
CONVECTIVE CHANCES DUE TO SYNOPTIC SCALE SUBSIDENCE OVER THE REGION.
MAX TEMPS WILL RUN A GOOD 10+ DEGREES ABOVE CLIMO. WILL ALLOW FOR
SOME LOW CHANCE POPS AND COOLER TEMPS FOR THU WITH THE ARRIVAL OF
THE BACKDOOR FRONT. STAYED CLOSE TO HPC GUIDANCE FIELDS.

&&

.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
AT KCLT...GUSTY SOUTH WINDS WITH THICKENING CIRRUS AND PERHAPS SOME
5000FT-BASED CU THIS AFTN. GUSTY CONDITIONS SHOULD DISSIPATE BY MID
EVENING...AS BANDS OF SHRA/TSRA ARE EXPECTED TO REACH THE CLT AREA
AROUND MIDNIGHT. LINGERING SHRA/TSRA MAY REMAIN OVER THE PIEDMONT
THROUGH THE REST OF THE NIGHT...BUT COVERAGE APPEARS LIMITED. A COLD
FRONT WILL STALL OVER THE AREA...SO PLENTY OF MOISTURE AROUND...MAY
SEE MVFR CIGS NEAR DAYBREAK...BUT CONFIDENCE IS MARGINAL. THE MAIN
THING WILL BE REDEVELOPMENT OF SHRA/TSRA BY MIDDAY FRIDAY. HAVE HIGH
ENUF POP TO ADD MENTION AT 15Z WITH CB.

ELSEWHERE...GUSTY SSW WINDS WILL CONTINUE UNTIL AT LEAST SUNSET.
GUSTY CONDITIONS SHOULD DISSIPATE BY MID EVENING. BANDS OF SHRA/TSRA
ARE EXPECTED TO SWEEP ACROSS THE WESTERN CAROLINAS AND NE GEORGIA
BETWEEN 20Z TO 6Z. HAVE TWEAKED TIMING OF SHRA/CB MENTION...AS ALL
ACTIVITY STILL HOURS AWAY AND NOT VERY ORGANIZED AS OF 18Z. POCKETS
OF IFR CLOUDS MAY DEVELOP DURING THE PRE DAWN HOURS...ESPECIALLY
NEAR KAVL. VSBY LESS OF A CONCERN UNLESS WIDESPREAD RAIN DEVELOPS. A
COLD FRONT STALLS OVER THE AREA ON FRIDAY...WITH LINGERING
MOISTURE...EXPECT SCATTERED TO NUMEROUS SHRA/TSRA REDEVELOPING BY
MIDDAY. POPS ARE HIGH ENUF TO WARRANT MENTION AT ARND 15Z FRI.

OUTLOOK...CLUSTERS OF SHRA/TSRA WILL LINGER ACROSS THE REGION FRIDAY
AFTN/EVE. DRY AND WARM AIR MASS IS EXPECTED TO SETTLE OVER THE
FORECAST AREA THIS WEEKEND AND WILL REMAIN INTO THE MID WEEK.
DIURNAL SHRA/TSRA ARE POSSIBLE EACH AFTERNOON AND EVENING ACROSS THE
MTNS AND ADJACENT FOOTHILLS.

&&

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

&&

SYNOPSIS...BSH
NEAR TERM...ARK/JDL
SHORT TERM...BSH
LONG TERM...LG
AVIATION...ARK

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
514 PM EDT THU MAY 26 2011

GAZ010-017-018-026-028-029-NCZ033-048>053-058-059-062>065-501>510-
SCZ001>006-010-272115-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-MADISON-YANCEY-
MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-NORTHERN JACKSON-MACON-
SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-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-ANDERSON-
514 PM EDT THU MAY 26 2011

...SEVERE THUNDERSTORM WATCH 385 IN EFFECT UNTIL MIDNIGHT EDT
TONIGHT...

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

.DAY ONE...TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   SEVERE THUNDERSTORM WATCH.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

NCZ035>037-056-057-068>072-082-SCZ007>009-011>014-019-272115-
ALEXANDER-IREDELL-DAVIE-CATAWBA-ROWAN-CLEVELAND-LINCOLN-GASTON-
MECKLENBURG-CABARRUS-UNION NC-SPARTANBURG-CHEROKEE-YORK-ABBEVILLE-
LAURENS-UNION SC-CHESTER-GREENWOOD-
514 PM EDT THU MAY 26 2011

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

.DAY ONE...TONIGHT.

THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THE FOOTHILLS AND
PIEDMONT AHEAD OF AN APPROACHING COLD FRONT THIS EVENING. AT LEAST
SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE
OVERNIGHT HOURS. A FEW SEVERE STORMS ARE EXPECTED...MAINLY THIS
EVENING. THE MAIN SEVERE WEATHER THREATS WILL BE FROM DAMAGING
WIND GUSTS AND LARGE HAIL. HOWEVER...AN ISOLATED TORNADO CANNOT BE
RULED OUT. FREQUENT CLOUD TO GROUND LIGHTNING AND TORRENTIAL
RAINFALL WILL BE POSSIBLE WITH ANY STORM THAT DEVELOPS TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

LANE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
752 PM EDT THU MAY 26 2011

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

0640 PM     HAIL             4 ESE GREENVILLE        34.82N 82.31W
05/26/2011  E0.75 INCH       GREENVILLE         SC   NWS EMPLOYEE

            DIME SIZED HAIL AT ROPER MOUNTAIN.

0715 PM     HAIL             7 NNW GREER             35.03N 82.28W
05/26/2011  E0.50 INCH       GREENVILLE         SC   TRAINED SPOTTER

0720 PM     HAIL             5 W ANDERSON            34.52N 82.73W
05/26/2011  E0.50 INCH       ANDERSON           SC   PUBLIC

&&

OUTLAW

PRELIMINARY LOCAL STORM REPORT...CORRECTED HAIL SIZE
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
752 PM EDT THU MAY 26 2011

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

0640 PM     HAIL             4 ESE GREENVILLE        34.82N 82.31W
05/26/2011  E0.75 INCH       GREENVILLE         SC   NWS EMPLOYEE

            DIME SIZED HAIL AT ROPER MOUNTAIN.

0715 PM     HAIL             7 NNW GREER             35.03N 82.28W
05/26/2011  E0.75 INCH       GREENVILLE         SC   TRAINED SPOTTER

0720 PM     HAIL             5 W ANDERSON            34.52N 82.73W
05/26/2011  E0.50 INCH       ANDERSON           SC   PUBLIC

&&

OUTLAW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
801 PM EDT THU MAY 26 2011

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

0708 PM     TSTM WND DMG     TOWNVILLE               34.56N 82.90W
05/26/2011                   OCONEE             SC   TRAINED SPOTTER

            THE TOWNVILLE FIRE DEPARTMENT ROOF IS OFF AND ON POWER
            LINES.

&&

OUTLAW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
802 PM EDT THU MAY 26 2011

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

0747 PM     HAIL             LENOIR                  35.91N 81.53W
05/26/2011  E1.00 INCH       CALDWELL           NC   TRAINED SPOTTER

&&

LG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
811 PM EDT THU MAY 26 2011

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

0810 PM     HAIL             3 NE LENOIR             35.94N 81.50W
05/26/2011  E0.75 INCH       CALDWELL           NC   TRAINED SPOTTER

&&

LG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
818 PM EDT THU MAY 26 2011

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

0815 PM     TSTM WND DMG     ELBERTON                34.11N 82.86W
05/26/2011                   ELBERT             GA   911 CALL CENTER

            TREES AND POWER LINES DOWN THROUGHOUT THE COUNTY AND
            REPORTS OF SOME ROOFS BLOWN OFF.

&&

LG