Severe Thunderstorm Warning 67, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
736 PM EDT THU MAY 8 2008

.SYNOPSIS...
A COLD FRONT WILL MOVE INTO THE REGION TONIGHT AND THEN STALL OUT ON
FRIDAY. WEAK HIGH PRESSURE WILL TEMPORARILY PUSH THIS FRONT SOUTH OF
THE AREA ON SATURDAY BEFORE RETURNING NORTH AS A WARM FRONT ON
SUNDAY. DRY NORTHWEST FLOW WILL THEN FOLLOW FOR EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
UPDATED THE GRIDS TO INCLUDE THE NEW TORNADO WATCH 282 HEADLINE.
RADAR TRENDS HAVE SHOWN GOOD ORGANIZATION...INCLUDING MESO LOW AND
BWER SIGNATURES ACROSS THE NORTHERN NC FOOTHILLS WITH THE DISCRETE
CELLS. WILL EXPECT MORE COVERAGE AND FORMATION TO THE EAST AND
SOUTH TONIGHT AS STRONG UPPER DYNAMICS AND LLVL JET MOVE INTO THE
AREA.

FORECAST HAS BEEN UPDATED TO DELAY HIGHER POPS INTO THE EASTERN
PIEDMONT UNTIL LATER THIS EVENING. ALTHOUGH CONVECTION HAS BEEN SLOW
TO DEVELOP INTO THE FORECAST AREA...18Z MODEL RUNS ARE SHOWING
FORCING DEVELOPING FROM THE SOUTHWEST AROUND 00Z AND SPREADING NE
ACROSS THE CWFA. THE HIGHER POPS STILL LOOK LIKE A VERY GOOD
BET...BUT THE SEVERE WEATHER POTENTIAL REMAINS A QUESTION.
PERSISTENT SOUTHERLY FLOW IS ALLOWING THE EARLY AFTN MIXOUT OF
DEWPOINTS TO MODERATE A LITTLE BIT...AND INSTABILITY MAY ACTUALLY
INCREASE AROUND SUNSET AS THE LOW LEVEL EQUIVALENT POTENTIAL
TEMPERATURE RIDGE MOVES INTO THE REGION. ALSO...LOW LEVEL FLOW
SHOULD EXIHIBIT CONTINUED BACKING AS THE 850 MB LOW CENTER
APPROACHES FROM THE WEST. WILL THUS KEEP THUNDER MENTION GOING AND
CONTINUE TO HIGHLIGHT SEVERE THREAT IN THE EXISTING HWO.

STILL EXPECT CONTINUED CONVECTION AFTER MIDNIGHT. MODELS INDICATE
THAT GREATEST COVERAGE OF SHOWERS/STORMS WILL BE OVER NC WITH LESSER
COVERAGE SOUTH ACROSS SC AND GA. HENCE...ONLY SCATTERED POPS ACROSS
THE WESTERN PORTION OF THE SOUTHERN UPSTATE AND NE GA AND LOWER QPF.
THE DEEPER MOISTURE BAND CLEARS THE AREA BY 12Z FRI ALONG WITH ANY
RESIDUAL PRECIP. DOWNSLOPE FLOW SHOULD QUICKLY SCOUR COUDS AWAY AND
EXPECT GENERALLY CLEAR CONDITIONS BY MID MORNING FRI. MIN TEMPS WERE
GENERATED BY USING A MOS BLEND.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
AS OF 320 PM THURSDAY...BY FRIDAY AFTERNOON THE COLD FRONT SHOULD
BECOME STATIONARY NEAR THE NC/SC STATE LINE. I EXPECT THAT THE
FRONTAL PRECIPITATION WOULD PUSH EAST OF THE CWA BY FRIDAY
AFTERNOON. HOWEVER...A FEW LINGERING CONVECTIVE SHRA/TSRA MAY REMAIN
NEAR THE TN LINE. MILD LLVL THICKNESSES AND INCREASING INSOLATION
SHOULD TEMPERATURES IN THE MID 70S IN THE MTNS AND L80S EAST.

FRIDAY NIGHT...A DECENT S/W WILL RIPPLE ACROSS KY/TN WITH THE SFC
REFLECTION MOVING OVER THE SOUTHERN APPALACHIANS. LINGERING
INSTABILITY AND MARGINAL SYNOPTIC LIFT MAY SUPPORT SCT SHRA/TSRA
DURING THE PRE-DAWN HOURS. AFTER SUNRISE SAT...DRY HIGH PRESSURE
WILL NOSE SOUTHWARD ACROSS THE CWA. INSTABILITY SHOULD BECOME
INCREASINGLY LIMITED ACROSS NC THROUGH THE MORNING...PUSHING
INSTABILITY FURTHER SOUTH ACROSS SC DURING THE AFTERNOON.

SATURDAY NIGHT...THE CENTER OF HIGH PRESSURE WILL SHIFT OVER THE
ATLANTIC AS ANOTHER LOW PRESSURE SYSTEM ORGANIZES ACROSS THE MID
WEST. HIGH PRESSURE SHOULD CONTINUE TO NOSE ACROSS THE CWA THROUGH
THE DAY. HOWEVER...A WARM FRONT ASSOCIATED WITH THE LOW IS FORECAST
TO ROTATE NORTH ACROSS THE SOUTHERN APPALACHIANS SUN MORNING AND
AFTERNOON. THE WARM FRONT WILL STRUGGLE TO OVERCOME A WEAK IN-SITU
AREA CAD...KEEPING TEMPS ACROSS THE NC FOOTHILLS AND PIEDMONT
LIMITED TO AROUND 70. HOWEVER...THE UPPER SAVANNAH RIVER VALLEY AND
THE EASTERN UPSTATE MAY EMERGE OUT OF THE CAD DURING THE LATE
AFTERNOON. ALLOWING CAPE TO BUILD TO 1000 J/KG ALONG WITH VEERING
LLVL WIND FIELDS. ALONG AND EAST OF THE WEDGE BOUNDARY COULD SEE A
FEW STRONG TO SEVERE TSRA DURING THE AFTERNOON. A SIGNIFICANT COLD
FRONT SHOULD SWEEP ACROSS THE REGION DURING THE LATE AFTERNOON AND
EARLY EVENING. IT IS UNCERTAIN THAT ENOUGH INSTABILITY WILL REMAIN
AHEAD OF THE COLD FRONT TO SUPPORT A LINEAR MCS. IT DOES APPEAR THAT
THE TN BORDER AREAS WILL SEE THE STRONGEST CONVECTION AS THE STORMS
WILL ORIGINATE FROM THE WARM SECTOR ACROSS TN. SUN AFTERNOON AND
EVENING IS OUTLOOKED FOR POSSIBLE SEVERE TS IN SPCS DY4.

SUNDAY NIGHT...WIND FIELDS FROM THE SFC TO 1 KM WILL STRENGTHEN
SIGNIFICANTLY IN THE WAKE OF THE FRONT. IN FACT...H8 WINDS BRIEFLY
REACH 50-60 KTS ON THE GFS LATE SUNDAY NIGHT. I WILL INCREASE WINDS
ACROSS THE CWA AND INDICATE GUSTS RANGING FROM 25-30 KTS ACROSS THE
MTNS. IN ADDITION...STRONG CAA COULD BRING H85 TEMPS ACROSS THE TN
LINE TO 0C BY 12Z MON. USING A BLEND OF NATIONAL GUIDANCE AND GMOS I
WILL PAINT THE MTNS WITH TEMPS MAINLY IN THE 40S.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 315 PM THURSDAY...OVERALL THE 12Z GFS AND THE 00Z ECMWF AGREE
ON THE GENERAL PICTURE MON THROUGH THURS. MON MORNING BEGINS WITH
CLOSED UPPER LOW OVER THE MID ATLANTIC...WHICH MAKES LITTLE EASTWARD
PROGRESS THROUGHOUT THE DAY. MON SHOULD BE RELATIVELY DRY AND BREEZY
WITH GOOD PRESSURE GRADIENT IN PLACE ACROSS THE FA. WILL CARRY SOME
CHC POPS MAINLY ACROSS THE EAST TO ACCOUNT FOR THE POSSIBILITY OF
LINGERING SHOWERS. HEIGHTS RISE TUES AS UPPER RIDGE OVER THE MIDWEST
BEGINS TO NOSE IN AND THE UPPER LOW GRADUALLY MOVES OFF THE EAST
COAST. TEMPS WARM 7 TO 8 DEGREES IN RESPONSE TO THE INCOMING RIDGE.
CONTINUED DRY TUES NIGHT THROUGH EARLY WED AS UPPER RIDGE CONTINUES
TO TRANSLATE ACROSS THE EASTERN CONUS. NEXT SYSTEM BEGINS TAKING
SHAPE EARLY WED AS UPPER LEVEL DISTURBANCE AND SURFACE LOW MOVE OUT
OF THE PLAINS. THE GFS AND THE ECMWF DIFFER A BIT WITH THE HANDLING
OF THIS SYSTEM BUT BOTH SHOW THE DEVELOPMENT OF A RATHER STRONG COLD
FRONT POISED TO CROSS THE FA LATE WED. PERFECT PROG OF MODEL FIELDS
ALSO SHOWS THE POTENTIAL FOR A SEVERE WEATHER EVENT WED AFTERNOON
AND EVENING. THE GFS SHOWS 1000-1500 J/KG OF CAPE AND DEEP LAYER
SHEAR IN EXCESS OF 60 KTS AS THE FRONT CROSSES THE AREA. COOLER AIR
MOVES IN FOR THE LATTER PART OF THE WEEK AS BOTH MODELS CARVE OUT A
RATHER LARGE EAST COAST TROUGH. FOR NOW WILL ONLY CARRY CHC POPS WED
THROUGH THUR TO ACCOUNT FOR SOME UNCERTAINTY AT THE BACK END OF THE
FORECAST PERIOD.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS SHOULD REMAIN ACROSS THE REGION FOR THE AFTERNOON
HOURS. HOWEVER...INSTABILITY CONTINUES TO INCREASE ACROSS THE NC
PIEDMONT/FOOTHILLS. 12Z MODELS STILL INDICATE THAT AT LEAST
SCATTERED THUNDERSTORMS SHOULD DEVELOP ACROSS THIS AREA IN THE
22Z-01Z TIMEFRAME AS LEAD VORT MAX REACHES THE CAROLINAS.
THEREFORE...HAVE CARRIED A TEMPO AT KCLT/KHKY FOR THUNDERSTORMS WITH
MVFR CONDITIONS FROM 22-01Z. ALSO..THUNDERSTORMS SHOULD REACH THE NC
MOUNTAINS WITH A TEMPO AT KAVL FOR THUNDER AND MVF CONDITIONS FROM
21-00Z WITH STORMS REACHING KGMU/KGSP 00Z-03Z TIMEFRAME. STORMS
SHOULD BE MORE SCATTERED IN NATURE NEAR KAND...SO JUST A VCTS THERE.
HAVE CARRIED A SECOND TEMPO FOR THUNDER WITH COLD FRONT THAT WILL
CROSS THE AREA FROM W TO E IN THE 04Z-10Z TIMEFRAME. GENERALLY CAN
EXPECT MVFR CONDITIONS IN SHOWERS AND THUNDERSTORMS WITH PERHAPS A
COUPLE HOURS OF MVFR CEILINGS IN THE 06Z-12Z TIMEFRAME. FRONT MOVES
E OF THE AREA BY 12Z WITH DOWNSLOPE SCOURING OUT CLOUDS WITH SKC
CONDTIONS BY 15Z.

OUTLOOK...VFR CONDITIONS SHOULD PREVAIL GEERALLY THROUGH SAT WITH
SOME MVFR CLOUDS POSSIBLY DEVELOPING LATE SAT NIGHT. ANOTHER ROUND
OF SCT SHWRS/TSTMS AND CIG/VSBY RESTRICTIONS IS EXPECTED SUNDAY AND
SUNDAY NIGHT. DRY WEATHER AND VFR CONDITIONS ARE EXPECTED TO RETURN
MONDAY AND CONTINUE THROUGH TUESDAY.

&&

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

&&

SYNOPSIS...BSH
NEAR TERM...HG/LG/SBK
SHORT TERM...NED
LONG TERM...BSH
AVIATION...LG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
443 PM EDT THU MAY 8 2008

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-092045-
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-
443 PM EDT THU MAY 8 2008

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

.DAY ONE...TONIGHT

SEVERE THUNDERSTORMS ARE POSSIBLE THIS EVENING AND TONIGHT OVER
PARTS OF THE WESTERN CAROLINAS AND NORTHEAST GEORGIA. SOUTHERLY
WINDS WILL BRING ATLANTIC MOISTURE INTO THE NORTH CAROLINA
PIEDMONT AND THE UPSTATE EAST OF SPARTANBURG. AS LOW PRESSURE
APPROACHES FROM THE WEST...WIND SHEAR WILL INCREASE DURING THE
EVENING HOURS. THE COMBINATION OF INSTABILITY AND WIND SHEAR WILL
RESULT IN A RISK OF SEVERE THUNDERSTORMS ALONG AND EAST OF A LINE
FROM HICKORY TO SPARTANBURG TO CLEMSON LATER THIS EVENING.

THUNDERSTORMS THIS EVENING MAY BE PARTICULARLY STRONG...PRODUCING VERY
LARGE HAIL...DAMAGING WINDS AND EVEN A BRIEF TORNADO. THE AREA
THAT HAS THE GREATEST CHANCE OF SEEING SEVERE STORMS WILL BE
ACROSS THE UPPER SAVANNAH RIVER VALLEY AND ALONG AND EAST OF
INTERSTATE 85.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A STRONG COLD FRONT WILL CROSS THE REGION SUNDAY EVENING...BRINGING
ANOTHER CHANCE OF SEVERE WEATHER TO MUCH OF THE REGION.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
717 PM EDT THU MAY 8 2008

NCZ033-501>505-082345-
AVERY-BURKE MOUNTAINS-CALDWELL MOUNTAINS-GREATER BURKE-GREATER
CALDWELL-MCDOWELL MOUNTAINS-
717 PM EDT THU MAY 8 2008

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN MCDOWELL...NORTHERN
CALDWELL...NORTHWESTERN BURKE AND SOUTHEASTERN AVERY COUNTIES THROUGH
745 PM EDT...

AT 717 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 4 MILES NORTHEAST OF LAKE JAMES...OR 9 MILES
NORTHEAST OF MARION...MOVING NORTHEAST AT 36 MPH.

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

LIGHTNING...SMALL HAIL...AND WIND GUSTS OF 40 TO 50 MPH ARE EXPECTED
WITH THIS STORM.

JPT