Tornado in South Carolina, May 4, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
232 PM EDT MON MAY 4 2009

.SYNOPSIS...
A STATIONARY FRONT WILL REMAIN OVER THE AREA INTO EARLY
WEDNESDAY...EXTENDING FROM THE CENTRAL GULF STATES TO THE MID
ATLANTIC COAST. WEAK DISTURBANCES WILL PROPAGATE ALONG THE BOUNDARY
FROM WEST TO EAST...BEFORE THE BOUNDARY LIFTS NORTH OF THE AREA
WEDNESDAY. A COLD FRONT WILL PUSH INTO THE AREA THURSDAY...AND STALL
OVER THE SOUTHEAST STATES THROUGH SATURDAY. HIGH PRESSURE WILL THEN
BUILD INTO THE AREA FROM THE WEST FOR SUNDAY.

&&

.NEAR TERM /THROUGH TUESDAY/...
GENERALLY WEAK CONVECTION CONTINUES ACROSS THE FORECAST AREA THIS
AFTN AS SHORTWAVES ALOFT MOVE THROUGH IN THE WSW FLOW. STRONGER
CONVECTION ASSOCIATED WITH THE FL GULF COAST MCS WILL TRACK EASTWARD
TOWARD THE SE COASTLINE THIS EVENING. ADDITIONAL STRONG TO SEVERE
CONVECTION WILL FIRE EAST OF THE FORECAST AREA...WHERE DAYTIME
HEATING HAS BEEN MUCH STRONGER. TSTM COVERAGE WILL LIKELY EXPAND
ACROSS THE CWFA INTO THE LATE AFTN/EARLY EVENING HOURS AS UPPER
DIVERGENCE IMPROVES AND LOW LEVEL CONVERGENCE STRENGTHENS IN WRN NC
JUST SOUTH OF THE SURFACE BOUNDARY. LAPS CAPE VALUES LOOK BEST JUST
EAST OF INTERSTATE 77 WHERE TEMPS ARE AROUND 80 DEGREES.
HOWEVER...LITTLE DCAPE FOR WIND PRODUCTION IS EVIDENT...CAPES ARE
NOT CONCENTRATED ALOFT IN ANY FAVORABLE HAIL GROWTH REGIONS...AND
SHEAR IS NOT TERRIBLY IMPRESSIVE. WILL CONTINUE THE ENHANCED TSTM
WORDING IN THE HWO MAINLY FOR LOCATIONS ALONG AND EAST OF INTERSTATE
77 THROUGH EVENING.

LOW PRES CENTERS WILL CONTINUE TO RIDE EASTWARD ALONG THE FRONTAL
ZONE OVERNIGHT. AS THEY MOVE OFF THE MID ATLANTIC COAST
OVERNIGHT...THE FRONT MAY BRIEFLY BACKDOOR INTO THE NRN TIER OF THE
FORECAST AREA. MEANWHILE...THE NEXT UPSTREAM SHORTWAVE ROTATING
AROUND THE NRN PLAINS VORTEX WILL LIKELY REACH THE SOUTHERN
APPALACHIANS LATE TONIGHT INTO EARLY TUESDAY. FAIRLY DEEP MOISTURE
IN THE PROFILES WILL COMBINE WITH THESE FORCING SOURCES TO KEEP
HEALTHY CHANCES OF PRECIPITATION GOING THROUGH MUCH OF TUESDAY. ANY
STRONGER CONVECTION WOULD IMPACT THE HIGHER INSTABILITY AREAS OVER
THE SOUTHEAST PIEDMONT DURING THE AFTERNOON HOURS. TEMPS SHOULD BE
CAPPED IN THE 70S TUESDAY WITH MOIST PROFILES AND A FRONT IN THE
REGION ACROSS THE NRN TIER.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 155 PM MONDAY...WITH LOW-AMPLITUDE/QUASI-ZONAL FLOW EXPECTED
TO PERSIST ACROSS MUCH OF THE COUNTRY THROUGH AT LEAST MID-WEEK...
THE FRONTAL BOUNDARY WILL REMAIN QUASI-STATIONARY ACROSS/NEAR THE
FORECAST AREA. RELATIVELY WEAK RIPPLED IN THE UPPER FLOW WILL CAUSE
PERIODIC OSCILLATIONS IN THE BOUNDARY...AND ENHANCE CHANCES FOR
PRECIP ACROSS THE AREA.

IT APPEARS THAT ONE AREA OF SOMEWHAT ORGANIZED RAINFALL WILL BE
MOVING OUT OF THE AREA TUE EVENING. HOWEVER...THE SHORT TERM MODELS
ARE IN GENERALLY GOOD AGREEMENT THAT ANOTHER AREA OF CONVECTION WILL
ACCOMPANY A WEAK SURFACE WAVE MOVING ACROSS THE TENN VALLEY ON WED.
POPS HAVE BEEN INCREASED TO LIKELY TO ACCOUNT FOR THIS. THE MODELS
ALSO SUGGEST WIND SHEAR WILL BE SIGNIFICANT WED AFTERNOON...
SUGGESTING AN ENHANCED POTENTIAL FOR SEVERE WX. HOWEVER...MUCH
UNCERTAINTY EXISTS REGARDING THE DEGREE OF INSTABILITY THAT WILL BE
AVAILABLE...AS THIS WILL HINGE ON TIMING OF PRECIP/HOW MUCH (IF ANY)
SUN WE SEE WED MORNING.

CONDITIONS SHOULD DRY OUT SOMEWHAT FOR WED NIGHT AND THURSDAY.
HOWEVER...SUFFICIENT MOISTURE AND INSTABILITY WILL PERSIST TO
SUPPORT DIURNAL CONVECTION DURING THIS TIME. TEMPERATURES WILL
GENERALLY REMAIN ABOVE NORMAL THROUGH THE PERIOD...ALTHOUGH WED
HIGHS WILL LIKELY BE NEAR CLIMATOLOGY...OWING TO CLOUD COVER AND
PRECIP.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
AS OF 215 PM MONDAY...GOOD AGREEMENT IS SEEN THE MED RANGE MODELS
OUT THROUGH 144 HR...HOWEVER AFTER THAT SIGNIFICANT DIFFERENCES BTW
THE ECMWF AND THE GFS APPEAR...MAKING FOR A BELOW AVERAGE CONFIDENCE
FORECAST SAT NIGHT THROUGH NEW DAY 7. THE 00Z AND EVEN THE 12Z GFS
ARE OBVIOUSLY THE OUTLIER IN DEVELOPING PLAINS SFC LOW EASTWARD
AFTER SAT FROPA...WHILE THE GENERAL MODEL CONSENSUS AND MANY ENS
MEMBERS HAVE RISING HEIGHTS WITH A BROAD SFC HIGH BUILDING ACROSS
THE REGION.

SOUNDINGS INDICATE PLENTY OF SBCAPE AND ELCAPE CONTINUING AFTER 00Z
FRI TO KEEP MENTION OF TS IN THE GRIDS OVERNIGHT. VERY WEAK S/W
ENERGY TO UTILIZE BUT THE SFC CONVERGENCE LOOKS GOOD AS A WARM FRONT
WRAPS AROUND THE MTNS. DONT SEE A HUGE THREAT FOR SEVERE...BUT BY FRI
AFTERNOON SOME OF THE STORMS ESP ACROSS THE WESTERN MOST ZONES COULD
BECOME STRONG ENOUGH FOR LARGE HAIL AS FREEZING LEVELS DROP BELOW
10KFT. THE BROAD CYCLONIC FLOW ALOFT WILL CONTINUE THROUGH SAT AND
ALLOW ANOTHER ROUND OF STRONG TO SEVERE STORMS TO DEVELOP AHEAD
OF THE FROPA. ENUF ELCAPE AND LLVL BOUNDARIES SHOULD BE PRESENT ONCE
AGAIN OVERNIGHT TO WARRANT TS MENTION IN THE GRIDS. MODEL SOUNDINGS
ARE STILL STINGY WITH THE AMOUNT OF AVAILABLE SHEAR...EVEN NEAR THE
WEAK FRONT...SO A MAJOR SEVERE EPISODE IS NOT EXPECTED...YET A FRONT
PASSING THROUGH DURING MAX HEATING WITH DRY AIR ALOFT THIS TIME OF
YEAR ALWAYS HAS THE POTENTIAL TO PRODUCE QLCS/S...SO SAT COULD BE
THE DAY TO WATCH FOR ENHANCED CONVECTION AND LONG LIVED STORMS.

THE OP MODELS GENERALLY AGREE ON BUILDING H5 HEIGHTS SLOWLY SUN AND
MORE AGGRESSIVELY MON. EVEN THO THE GFS IS WAY TOO FAST MOVING THE
SFC HIGH OFFSHORE SUN NIGHT...AND SETTING UP A TOTALLY DIFFERENT
LLVL WIND FIELD...IT HAS AN UPPER PATTERN IS FAIRLY SIMILAR TO THE
ECMWF. THE GFS IS BASICALLY BRINGING VERY STRONG MLVL ENERGY THROUGH
THE DEVELOPING RIDGE...MOST OF WHICH LOOKS TOO STRONG OR SUSPICIOUS
IN ORIGIN. SO...THE FCST FOR SUN THROUGH MON WILL BE LEFT DRY AND
SIDE MORE SO WITH THE ECMWF AND NATIONAL GUIDANCE.

TEMPS WILL BE PRETTY WARM FRI AND SAT...PROBABLY ABOUT 5 DEGREES
ABOVE NORMAL...AS THE CWFA REMAINS IN THE WARM SECTOR. HOWEVER...A
DECENT AIRMASS CHANGE IS EXPECTED LATE SAT TO KEEP MAXES RIGHT
AROUND OR JUST A BIT BELOW NORMAL SUN...EVEN IN DOWNSLOPING W/LY
FLOW. ON MON...MAXES SHOULD HAVE NO PROBLEM CLIMBING A FEW DEGREES
ABOVE NORMAL AS THE UPPER RIDGE BUILDS TO THE WEST AND SUBSIDENCE
INCREASES ALLOWING VERY GOOD INSOLATION.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
VFR LEVEL CLOUDINESS ALONG WITH SCATTERED WEAK CONVECTION WILL
CONTINUE ACROSS THE TERMINAL FORECAST AREA MUCH OF THIS AFTERNOON.
COVERAGE OF THE SHOWERS AND THUNDERSTORMS WILL EXPAND DURING THE
LATE AFTERNOON HOURS AS BETTER UPPER SUPPORT ARRIVES IN THE
VICINITY. THE BEST CHANCE OF THUNDERSTORMS WILL BE FROM KHKY TO KCLT
AFTER 21Z. THE PROFILES REMAIN VERY MOIST TONIGHT...AND THE MOS AND
SOUNDINGS ARE STRUGGLING WITH THE DEPICTION OF CEILINGS. WILL REMAIN
MORE OPTIMISTIC THAN MOS AT PRESENT AND FEATURE CIGS BORDERING ON
IFR/MVFR MOST LOCATIONS AFTER 04Z. BETTER CONSENSUS ON IFR CIGS IS
INDICATED AT KAND/KAVL/KHKY...SO WILL FEATURE 600 TO 800 FEET CIGS
STARTING 05Z N TO 09Z S. THE WIND DIRECTION COULD GET A LITTLE
TRICKY OVERNIGHT IF THE BOUNDARY IS ABLE TO BACKDOOR INTO THE REGION
FROM THE N. STILL...SPEEDS SHOULD BE QUITE LIGHT. CIGS WILL RISE
INTO...OR REMAIN IN...THE MVFR RANGE THROUGHOUT BY MID MORNING
TUESDAY...WITH SCATTERED SHOWERS DEVELOPING AGAIN IN THE MOIST SW
FLOW ALOFT.

AT KCLT...SHOWERS WILL BECOME INCREASINGLY LIKELY AFTER 21Z...WITH
TS IN THE VICINITY THROUGH THE EVENING HOURS. SFC WINDS WILL BACK
AROUND TO SE AND BECOME LIGHT OVERNIGHT. WINDS COULD GO ENE LATE
TONIGHT DEPENDING ON THE SWD PROGRESS OF THE BACKDOOR COLD
FRONT...BUT SE LOOKS LIKE A BETTER BET OVERALL. MVFR CIGS ARE
EXPECTED FROM MIDNIGHT ONWARD...WITH IFR POSSIBLE AROUND DAYBREAK.

OUTLOOK...AN UNSETTLED PATTERN WILL CONTINUE THROUGH LATE WEEK AS A
SERIES OF LOW PRESSURE CENTERS RIPPLE NORTHEAST ALONG THE FRONTAL
BOUNDARY IN THE VICINITY. SCATTERED TO NUMEROUS AFTN SHOWERS AND
THUNDERSTORMS ARE EXPECTED. MORNING FOG/STRATUS WILL BE POSSIBLE
EACH DAY.

&&

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

&&

SYNOPSIS...SBK
NEAR TERM...HG
SHORT TERM...JDL
LONG TERM...SBK
AVIATION...HG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1123 AM EDT MON MAY 4 2009

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-051530-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-ALEXANDER-
IREDELL-DAVIE-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-CATAWBA-
ROWAN-GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
HENDERSON-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-UNION NC-
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-SPARTANBURG-CHEROKEE-YORK-
ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
1123 AM EDT MON MAY 4 2009

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SHOWERS AND THUNDERSTORMS EARLY THIS AFTERNOON WILL PRODUCE
LITTLE MORE THAN BRIEFLY HEAVY RAIN...ALTHOUGH AN OCCASIONAL CLOUD
TO GROUND LIGHTNING STRIKE WILL BE POSSIBLE. AS AN UPPER LEVEL
DISTURBANCE ARRIVES FROM THE WEST LATER THIS
AFTERNOON...THUNDERSTORM COVERAGE WILL INCREASE ACROSS THE WESTERN
CAROLINAS AND NORTHEAST GEORGIA. THE GREATEST CHANCE OF SEVERE
THUNDERSTORMS WILL BE IN PIEDMONT LOCATIONS...ESPECIALLY ALONG AND
EAST OF THE INTERSTATE 77 CORRIDOR...LATE THIS AFTERNOON THROUGH
THIS EVENING. THE MAIN THREAT WILL BE LARGE HAIL AND BRIEF BUT
DAMAGING WIND GUSTS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP ACROSS THE WESTERN CAROLINAS AND NORTHEAST GEORGIA ON
WEDNESDAY. THERE IS A SLIGHT RISK FOR SEVERE STORMS...WITH THE
MAIN THREAT BEING LARGE HAIL AND DAMAGING WINDS.

.SPOTTER INFORMATION STATEMENT...

NONE.

HG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
307 PM EDT MON MAY 04 2009

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

0827 PM     TSTM WND DMG     2 WSW WALHALLA          34.76N 83.09W
05/03/2009                   OCONEE             SC   COUNTY OFFICIAL

            ONE TREE DOWN ALONG COFFEE ROAD IN WALHALLA.

&&

BSH

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
349 PM EDT MON MAY 4 2009

NCZ033-501>505-042045-
AVERY-BURKE MOUNTAINS-CALDWELL MOUNTAINS-GREATER BURKE-GREATER
CALDWELL-MCDOWELL MOUNTAINS-
349 PM EDT MON MAY 4 2009

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN CALDWELL...NORTHERN
MCDOWELL...NORTHWESTERN BURKE AND SOUTHERN AVERY COUNTIES THROUGH 445
PM EDT...

AT 347 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES SOUTHWEST OF ASHFORD...OR 8 MILES
SOUTHEAST OF SPRUCE PINE...MOVING NORTHEAST AT 25 MPH.

* OTHER LOCATIONS AFFECTED INCLUDE BUT ARE NOT LIMITED TO UPTON...
  PATTERSON...KINGS CREEK...GLOBE...EDGEMONT...TABLE ROCK...
  COLLETTSVILLE AND ASHFORD.

SMALL HAIL...HEAVY RAINFALL...AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM.

07