Severe Thunderstorm Warning 35, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
243 PM EDT FRI APR 10 2009

.SYNOPSIS...
STRONG LOW PRESSURE WILL PASS BY TO THE NORTH TONIGHT...DRAGGING A
COLD FRONT ACROSS THE REGION. HIGH PRESSURE WILL SLOWLY BUILD IN
FROM THE NORTHWEST SATURDAY THROUGH SUNDAY. ANOTHER LOW PRESSURE
SYSTEM WILL APPROACH FROM THE WEST BY MONDAY...BRINGING UNSETTLED
WEATHER TO THE REGION THROUGH THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS THE DEEP UPPER LOW PRES CENTER MOVES EAST THROUGH KY LATE THIS
AFTERNOON THROUGH THIS EVENING...STRONG DPVA AHEAD OF THIS FEATURE
WILL LIFT ACROSS THE FORECAST AREA 21Z TO 00Z. MEANWHILE...A 130 KT
UPPER LEVEL JET STREAK WILL STRETCH ACROSS THE DEEP SOUTH THIS
EVENING...PRODUCING STRONG DIVERGENCE IN THE LEFT EXIT REGION OVER
THE WESTERN CAROLINAS. THIS WILL ALLOW CONVECTIVE COVERAGE TO
STEADILY INCREASE ACROSS THE AREA. THE MAIN UPPER FORCING WILL MOVE
ACROSS THE FORECAST AREA FROM THE WEST BETWEEN ABOUT 8 PM AND 1 AM.
LOW LEVEL FLOW SHOULD BEGIN TO BACK SHARPLY TOWARD 21Z...STRONGLY
ENHANCING LOW LEVEL HELICITY. A TONGUE OF LOWER 60S DEWPOINTS
COINCIDENT WITH THE BETTER SHEAR AXIS WILL TRAVERSE THE SRN PART OF
THE FORECAST AREA THIS EVENING TO GREATLY ENHANCE THE ORGANIZED
SEVERE TSTM THREAT. A WATCH IS LIKELY LATER THIS AFTERNOON OR THIS
EVENING.

850 MB FLOW WILL TURN QUICKLY WESTERLY OVERNIGHT FOLLOWING
FROPA...PRODUCING DOWNSLOPE DRYING EAST OF THE MTNS. NORTHWEST FLOW
SHOULD ALLOW UPSLOPE SHOWERS TO CONTINUE ALONG THE SPINE OF THE
SOUTHERN APPALACHIANS THROUGH SATURDAY MORNING...ALONG WITH WINDY
CONDITIONS IN THE COLD ADVECTION FLOW. PROFILES STAY WARM ENOUGH FOR
THE PTYPE TO REMAIN LIQUID. CONTINUED CLEARING THROUGHOUT IS
EXPECTED SAT AFTN. A STRONG GRADIENT IN MAX TEMPS WILL
DEVELOP...WITH HIGHS GENERALLY IN THE 50S IN THE MTNS AND LOW TO MID
70S IN THE SE PIEDMONT.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 205 PM FRIDAY...UPPER LEVEL RIDGE CONTINUES TO BUILD ACROSS
THE MIDWEST SAT NIGHT WHILE THE LAST LOBE OF S/W ENERGY CROSSES THE
CWFA TO THE EAST. THE GFS AND THE NAM BOTH AGREE ON THIS WAVE
LEAVING THE AREA BY 06Z THUS ENDING ANY REAL CHANCE OF PRECIP.
THE 12Z GFS DOES HANG ONTO H85 MOISTURE THROUGH THE DAY SUNDAY WHICH
DOESNT MAKE MUCH SENSE CONSIDERING ITS BRINGING IT ACROSS THE MTNS
IN DOWNSLOPE FLOW AND INTO AN INCREASING SUBSIDENCE INVERSION.
HOWEVER...THE 12Z GFS HAS COME IN DRIER THAN THE 00Z GFS WHICH
COMPARES MORE FAVORABLY WITH THE EVEN DRIER 12Z NAM. SO...WONT
EXPECT MUCH CLOUD COVER NOR ANY UPSLOPE PRECIP AS DEPICTED BY THE
GFS. THE MODELS DO AGREE ON DEVELOPING A FAIRLY STRONG INSITU WEDGE
LATE SUNDAY AND MAINTAINING IT THROUGH MON. THE GFS IS MORE BULLISH
WITH THE STRENGTH...BUT IN EITHER CASE THE EXPECTED WX SHOULD BE
SIMILAR. THIS SITUATION HAS LED TO PUSHING BACK CHC POPS SUN NIGHT
UNTIL AFTER 06Z MON FOR THE WRN THIRD OF THE CWFA. BASICALLY A DRY
WEDGE SETTING UP SUN...BECOMING A MOIST WEDGE SUN NIGHT THROUGH MON.

UPPER LEVEL SUPPORT WILL BE LOW WITH THE NEXT LOW PRESSURE SYSTEM
AND COLD FRONT. H5 PVU/S ARE LESS THAN 1 AND H3 DIV REMAINS NW OF THE
MTNS. ALSO...ANOTHER SIGN OF THE CLASSICAL GSP SLIT WILL BE
INCREASED INSTABILITY TO THE SOUTH AND WEST. BUFKIT SOUNDINGS FOR
KGSP INDICATE LI/S WILL REMAIN ABOVE 10 THROUGH MON AND THE NAM
KEEPS ALL THE CONVECTIVE PRECIP OVER AL AND SRN GA THROUGH 00Z TUE.
SO SUFFICE TO SAY...THE CHC THUNDER HAS BEEN REMOVED FROM THE GRIDS
MON. STILL EXPECT LIKELY POPS MON AFTERNOON AND EVENING AS WEDGE
CONTINUES TO HOLD AND PROVIDE VERY GOOD ISENTROPIC LIFT FOR
WIDESPREAD -RA. MIN TEMPS ARE EXPECTED TO BE RIGHT AROUND NORMAL
SUN...AND FEW ABOVE NORMAL MON AS OVC SKIES DEVELOP. HIGHS SHOULD
ALSO BE RIGHT AROUND NORMAL SUN...WITH GOOD INSOLATION OFFSETTING AN
INCREASING NE/LY FLOW AND WEAK CAA. HIGHS FOR MON WILL BE ABOUT 10
DEGREES BELOW NORMAL AS MOIST WEDGE SETS UP EARLY AND PERSISTS
THROUGHOUT THE DAY.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 240 PM FRIDAY...THE EXT RANGE BEGINS WITH STABLE WEDGE
REMAINING IN CONTROL...HOWEVER UPPER DYNAMICS WILL BE INCREASING
THROUGH MON NIGHT AND DURING THE DAY TUE. THE WEDGE SHOULD BREAKDOWN
BY 12Z AS THE COLD FRONT CROSSES THE REGION. STILL DONT SEE MUCH
UPPER SUPPORT WITH THIS FRONT. VORTICITY LOOKS TO REMAIN STREAMLINED
WITH UPPER LOW AND THE STRONGEST FORCING CROSSES THE LOWER OH
VALLEY. HARD TO JUDGE THE AMOUNT OF LLVL INSTABILITY DEVELOPING
TUE AS THE WEDGE BREAKS DOWN FROM THE SW. SOME EVIDENCE EXISTS FOR
TS POTENTIAL WITH LI/S DROPPING INTO THE LOWER SINGLE DIGITS AND
WEAK ELEVATED CAPE SHOWING UP ON THE SOUNDINGS. ALSO...BOTH THE GFS
AND THE ECMWF INDICATE ANOTHER POSSIBLE TRIPLE POINT LOW CROSSING
THE UPSTATE AND PIEDMONT BTW 18Z AND 00Z. FOR NOW...WILL KEEP ALL
THE PRECIP NON/CONVECTIVE AS TOO MUCH UNCERTAINTY EXISTS WITH THE
TIMING OF THE WEDGE BREAKDOWN AND INCREASING INSTABILITY POTENTIAL.
A PROGRESSIVE PATTERN IS EXPECTED THO...AND BY 06Z THE FRONT SHOULD
BE NEAR THE COAST.

ANOTHER WEAK WEDGE BUILDS IN THU AND REMAINS THROUGH FRI AHEAD OF
YET ANOTHER SYS PUSHING INTO THE DEEP SOUTH. THE 12Z GFS HAS SLOWED
DOWN AND IS MORE INLINE WITH THE 00Z ECMWF. THIS GIVE THE MED RANGE
FCST BETTER CONFIDENCE AS THE GFS WAS PRETTY MUCH THE ONLY MODEL
HANGING ONTO THE FASTER SOLN. SOLID CHC POPS STILL LOOK GOOD FOR FRI
LINGERING INTO SAT AS THE AXIS OF THE SFC TROF SHOWS GOOD CONTIGUITY
BTW THE OP MODELS. WONT EXPECT MUCH OF A WARM UP THROUGH THE
REMAINDER OF THE WEEK...HOWEVER TEMPS WILL BE RIGHT AROUND NORMAL.
THE LLVL WIND FIELD REALLY DOESNT GET A S/LY COMPONENT UNTIL LATE
FRI AHEAD OF THE NEXT FRONT...BEFORE THAT A WEAKENING WEDGE WIND
FIELD...NE/LY TO SE/LY IS EXPECTED. PLENTY OF SUNSHINE WED THROUGH
FRI WILL HELP MAX TEMPS REACH AROUND 70 F NON/MTNS...MID 60S
MTNS...IF NOT A FEW DEGREES ABOVE THU AND FRI.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
CONVECTION CONTINUES TO FIRE ALONG AND NW OF THE INTERSTATE 85
CORRIDOR THIS AFTERNOON IN A REGION OF STRONGER LOW LEVEL
CONVERGENCE AND UPSLOPE FLOW. THE GREATEST THUNDERSTORM THREAT
THROUGH 21Z WILL BE FROM KAND TO KGSP...BUT THUNDERSTORMS WILL
BECOME MORE WIDESPREAD THROUGH THE LATE AFTERNOON AND EVENING HOURS
AS THE BETTER UPPER SUPPORT ARRIVES. TEMPO IFR CONDITIONS ARE
EXPECTED IN THE HEAVIEST SHOWERS...WITH GENERALLY PERSISTENT MVFR
CONDITIONS ELSEWHERE. FLOW WILL REMAIN SOUTHERLY...WITH A FEW GUSTS
NEAR THUNDERSTORMS. THE BEST COVERAGE OF THUNDERSTORMS...WITH THE
HIGHEST RISK OF ASSOCIATED LIGHTNING AND SEVERE GUSTS...WILL BE FROM
00Z WEST TO 05Z EAST WITH CONVECTION ALONG THE MAIN FRONTAL PASSAGE.

AT KCLT...SHOWERS WILL INCREASE FROM THE SW...WITH TEMPO
THUNDERSTORMS THROUGH LATE AFTERNOON. MORE WIDESPREAD THUNDERSTORMS
WILL DEVELOP BY 00Z THIS EVENING. SSW WINDS WILL BACK SLIGHTLY TO
SOUTH AHEAD OF THE APPROACHING FRONT...AND STRONG TO SEVERE
THUNDERSTORMS WILL LIKELY CROSS THE TERMINAL BETWEEN 02Z AND 05Z
LATER THIS EVENING. WINDS WILL SHIFT TO WESTERLY BEHIND THE PASSING
FRONT...WITH MVFR CONDITIONS SLOW TO SCATTER THROUGH DAYBREAK.

OUTLOOK...DRY HIGH PRESSURE WILL BUILD INTO THE REGION SAT AFTERNOON
THROUGH SUNDAY. THE NEXT STORM SYSTEM WILL BRING MOISTURE BACK INTO
THE AREA SUNDAY NIGHT THROUGH TUESDAY...WITH ASSOCIATED RESTRICTIONS
DEVELOPING. SOME IMPROVEMENT IS EXPECTED TOWARD THE MIDDLE OF NEXT
WEEK.

&&

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

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
343 PM EDT FRI APR 10 2009

GAZ010-017-018-026-NCZ051-052-058-059-062-063-111945-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-SWAIN-HAYWOOD-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-
343 PM EDT FRI APR 10 2009

...TORNADO WATCH 134 IN EFFECT UNTIL 10 PM EDT THIS EVENING...

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

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

   TORNADO WATCH.

LOW PRESSURE WILL MOVE ACROSS THE SOUTHERN APPALACHIANS THIS
EVENING. MOIST AND UNSTABLE AIR IN ADVANCE OF THE APPROACHING COLD
FRONT ASSOCIATED WITH THIS LOW WILL ALLOW SCATTERED SEVERE
THUNDERSTORMS TO DEVELOP THROUGH THE LATE AFTERNOON HOURS. THROUGH
6 PM THIS EVENING...THE GREATEST THREAT OF SEVERE THUNDERSTORMS
WILL BE ACROSS NORTHEAST GEORGIA...UPSTATE SOUTH CAROLINA...AND
THE SOUTHERN FOOTHILLS AND PIEDMONT OF NORTH CAROLINA. LARGE HAIL
WILL BE THE MAIN THREAT ASSOCIATED WITH THESE THUNDERSTORMS.

WINDS WILL INCREASE ACROSS THE REGION THIS EVENING AHEAD OF THE
COLD FRONT...ALLOWING THUNDERSTORMS TO BECOME MORE ORGANIZED. THE
THREAT WILL THEN SHIFT FROM HAIL TO A COMBINATION OF
WIND...HAIL...AND POSSIBLE ISOLATED TORNADOES THROUGH LATE
EVENING.

WHILE SEVERE THUNDERSTORMS MAY AFFECT ANY LOCATION IN THE WESTERN
CAROLINAS AND NORTHEAST GEORGIA THIS EVENING...LOCATIONS SOUTH OF
A LINE FROM ASHEVILLE TO CHARLOTTE WILL SEE THE GREATEST THREAT. A
SEVERE THUNDERSTORM OR TORNADO WATCH WILL LIKELY BE NEEDED THIS
EVENING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

.SPOTTER INFORMATION STATEMENT...

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

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

GAZ028-029-NCZ033-035>037-048>050-053-056-057-064-065-068>072-082-
501>510-SCZ001>014-019-111945-
HART-ELBERT-AVERY-ALEXANDER-IREDELL-DAVIE-MADISON-YANCEY-MITCHELL-
BUNCOMBE-CATAWBA-ROWAN-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-
343 PM EDT FRI APR 10 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.

LOW PRESSURE WILL MOVE ACROSS THE SOUTHERN APPALACHIANS THIS
EVENING. MOIST AND UNSTABLE AIR IN ADVANCE OF THE APPROACHING COLD
FRONT ASSOCIATED WITH THIS LOW WILL ALLOW SCATTERED SEVERE
THUNDERSTORMS TO DEVELOP THROUGH THE LATE AFTERNOON HOURS. THROUGH
6 PM THIS EVENING...THE GREATEST THREAT OF SEVERE THUNDERSTORMS
WILL BE ACROSS NORTHEAST GEORGIA...UPSTATE SOUTH CAROLINA...AND
THE SOUTHERN FOOTHILLS AND PIEDMONT OF NORTH CAROLINA. LARGE HAIL
WILL BE THE MAIN THREAT ASSOCIATED WITH THESE THUNDERSTORMS.

WINDS WILL INCREASE ACROSS THE REGION THIS EVENING AHEAD OF THE
COLD FRONT...ALLOWING THUNDERSTORMS TO BECOME MORE ORGANIZED. THE
THREAT WILL THEN SHIFT FROM HAIL TO A COMBINATION OF
WIND...HAIL...AND POSSIBLE ISOLATED TORNADOES THROUGH LATE
EVENING.

WHILE SEVERE THUNDERSTORMS MAY AFFECT ANY LOCATION IN THE WESTERN
CAROLINAS AND NORTHEAST GEORGIA THIS EVENING...LOCATIONS SOUTH OF
A LINE FROM ASHEVILLE TO CHARLOTTE WILL SEE THE GREATEST THREAT. A
SEVERE THUNDERSTORM OR TORNADO WATCH WILL LIKELY BE NEEDED THIS
EVENING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

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