Severe Thunderstorm Warning 93, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
814 AM EDT FRI MAY 8 2009

.SYNOPSIS...
A STATIONARY FRONT WILL WEAKEN OVER THE AREA TODAY. A COLD FRONT
WILL MOVE IN FROM THE NORTHWEST TONIGHT...AND WILL STALL AND WEAKEN
ACROSS THE AREA SATURDAY. ANOTHER COLD FRONT WILL SWEEP ACROSS THE
AREA LATE SATURDAY...STALLING JUST TO THE SOUTH. THIS FRONT WILL
FINALLY MOVE OFF TO THE SOUTH LATE MONDAY. HIGH PRESSURE WILL THEN
BUILD OVER THE REGION FOR THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
MCS APPROACHING NC MTNS WITHOUT SIGNS OF WANING SO WILL ISSUE A
QUICK UPDATE TO BUMP POP/CLOUDS/QPF UP AND TEMPS DOWN TO REFLECT
LATEST TRENDS.

PREVIOUS DISCUSSION...AN EXPANDING AREA OF DENSE FOG HAS DEVELOPED
AROUND CLT METRO OWING TO RECENT RAINFALL...LIGHT WIND...AND CLEAR
SKY. EXPECT THE DENSE FOG TO CONTINUE EXPANDING ACROSS THE PIEDMONT
THROUGH SUNRISE...SO THINK IT BEST TO HOIST THE DENSE FOG ADVISORY.
THE FOG SHOULD BURN OFF QUICKLY AFTER SUNRISE.

A NEARLY ZONAL UPPER PATTERN WILL CONTINUE THROUGH THE NEAR TERM
WITH WEAK VORT CENTERS RIPPLING OVERHEAD. THE MODELS GENERALLY AGREE
THAT THE NEXT WEAK SHORT WAVE WILL MOVE IN FROM THE WEST LATE TODAY
OR THIS EVENING ALONG WITH SOME UPPER DIVERGENCE IN THE RIGHT
ENTRANCE REGION OF THE JET. DETAILS ARE SKETCHY BECAUSE OF
CONVECTIVE FEEDBACK ISSUES IN THE GFS...BUT THINK THE MODEL HAS GOT
A GENERAL SENSE OF HOW IT SHOULD PLAY OUT. MOISTURE REMAINS
PLENTIFUL ENOUGH TO FUEL THUNDERSTORM DEVELOPMENT...WITH MODEL CAPE
INTO THE 1000-1500 J/KG RANGE. SO...IN THE ABSENCE OF ANYTHING THAT
WOULD DISCOURAGE DEEP CONVECTION...WE CAN EXPECT SCATTERED MAINLY
AFTERNOON AND EVENING STORMS. IF THINGS DEVELOP AS EXPECTED...AN
UPSTREAM MCS COULD REACH THE MOUNTAINS THIS EVENING BEFORE IT FALLS
APART...SO THE SLIGHT RISK LOOKS PLAUSIBLE. THE CONVECTION COULD
LINGER OVERNIGHT OVER THE WEST AS AN UPSTREAM BOUNDARY DRIFTS IN.
WILL MENTION POSSIBILITY OF A FEW SEVERE THUNDERSTORMS IN THE HWO.
TEMPS WERE NUDGED TOWARD A GUIDANCE BLEND.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
ZONAL UPPER LEVEL FLOW WILL EXIST OVER THE SOUTHEAST ON SATURDAY AND
SUNDAY. A WEAKENING COLD FRONT EMANATING FORM A LOW IN NORTHERN VA
WILL EXTEND ACROSS THE CENTRAL AND WESTERN CAROLINAS SATURDAY
MORNING...PROVIDING MOISTURE AND A FOCUSING MECHANISM FOR
CONVECTION. CAPE ALONG THE FRONT IS EXPECTED TO BE SUBSTANTIAL...AND
SEVER WEATHER WILL MENTIONED IN THE HAZARDOUS WEATHER OUTLOOK.

A SECOND AND BETTER DEFINED COLD FRONT WILL APPROACH THE AREA FROM
THE WEST LATE SATURDAY..CROSSING THE AREA OVERNIGHT...AND
SUPPORTING NOCTURNAL CONVECTION. THIS FRONT MOVES SOUTH OF THE AREA
ON SUNDAY...BUT AT A SLOW ENOUGH PACE THAT ITS MOISTURE WILL EXTEND
OVER THE AREA THROUGH SUNDAY NIGHT...SUPPORTING PRECIPITATION
CHANCES...AND PERHAPS SOME ELEVATED CONVECTION OVER GA AND SC.
TEMPERATURES RANGES WILL BE LIMITED IN CLOUD COVER AND ELEVATED DEW
POINTS.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
THE LATEST RUNS OF THE GFS AND ECMWF ARE IN GENERAL AGREEMENT
THROUGH MONDAY ON 500 MB ZONAL FLOW EVOLVING INTO A LOW AMPLITUDE
EAST COAST TROUGH BY MONDAY...WITH THE ECMWF BECOMING SLIGHTLY
SLOWER WITH THE PROGRESSION OF THIS FEATURE. YESTERDAY HPC PREFERRED
THE GFS OVER THE SLOWER ECMWF BECAUSE OF SUPPORT FROM THE CANADIAN
AND THE ENSEMBLE MEANS...AND THIS SOLUTION WILL BE MAINTAINED IN
THIS PACKAGE.

A COLD FRONT WILL BE LOCATED NEAR THE COAST ON MONDAY...WITH
MOISTURE LINGERING BEHIND IT AS A SURFACE WAVE MOVES ALONG THE
BOUNDARY. POPS WILL REMAIN IN THE FORECAST THROUGH MONDAY....WITH
THUNDER LIMITED TO GA AND SC. THE FRONT WILL MOVE SOUTH INTO FL BY
TUESDAY AS HIGH PRESSURE MOVES FORM THE PLAINS TO THE OH VALLEY.
THIS WILL ALLOW OUR AREA TO DRY OUT AND COOL OFF. BY WEDNESDAY THE
HIGH MOVES TO NEW ENGLAND...AND THE FRONT STRETCHES FROM CENTRAL FL
TO LA. GULF INFLOW APPEARS TO BE FAR ENOUGH WEST OF OUR AREA TO
LIMIT THE GREATEST MOISTURE INCREASE TO THE MOUNTAINS. BY THURSDAY
MOISTURE AHEAD OF AND APPROACHING COLD FRONT WILL SUPPORT ISOLATED
CONVECTION.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AREAS OF DENSE FOG AND LOW STRATUS ACROSS THE PIEDMONT AND FOOTHILLS
EARLY THIS MORNING SHOULD DISSIPATE BY MID MORNING. AFTER THAT...THE
SITUATION BECOMES MORE COMPLICATED THAN PREVIOUSLY THOUGHT...
ALTHOUGH VFR CONDITIONS SHOULD BE THE RULE. LARGE AREA OF
THUNDERSTORMS MOVING ACROSS MIDDLE TN WILL CONTINUE MOVING EAST AND
SHOULD BEGIN TO WEAKEN DURING MID MORNING AS IT APPROACHES THE MTNS.
THIS ACTIVITY COULD MAKE IT TO KAVL WITH LOWER VIS/CEILING IN LATE
MORNING...BUT MOST LIKELY WILL NOT HAVE MUCH LEFT BY THEN.
OTHERWISE...CONVECTIVE DEBRIS COULD DELAY THE ONSET OF DEEP
CONVECTION OUTSIDE THE MTNS...WHICH IS ALL THE MORE REASON TO KEEP
SHOWERS OUT OF THE FORECAST FOR NOW.

AT KCLT...VERY LOW IFR VISIBILITY COULD BE HIGHLY VARIABLE EARLY
THIS MORNING...BUT IN THE END THE LOW STUFF SHOULD PREVAIL UNTIL
ABOUT 13Z...WHEN IT SHOULD BURN OFF QUICKLY. WIND SHOULD COME UP
FROM THE SOUTH FROM MID MORNING ONWARD. FROM THAT POINT ON...SHOULD
BE VFR.

OUTLOOK...CHANCE OF MAINLY LATE DAY SHWRS/TSTMS WILL CONT WITH MRNG
LOW CLOUDS/FOG. ANOTHER COLD FRONT WILL PUSH SE INTO AREA THIS
WEEKEND AND STALL INTO EARLY NEXT WEEK WITH CHANCE SHOWERS/TSTMS AND
CIG/VSBY RESTRICTIONS. THEN HIGH PRES BUILDS IN FROM THE N FOR MID
WEEK.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR NCZ035-056-
     068>072-082-502-504.
SC...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR SCZ007>009-
     012>014.

&&

SYNOPSIS...JAT
NEAR TERM...PM/RB
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...PM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
546 AM EDT FRI MAY 8 2009

GAZ010-017-NCZ033-048>053-058-059-062>065-501-503-505-507-509-
SCZ001>003-091015-
RABUN-HABERSHAM-AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-
GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
HENDERSON-CALDWELL MOUNTAINS-BURKE MOUNTAINS-MCDOWELL MOUNTAINS-
RUTHERFORD MOUNTAINS-POLK MOUNTAINS-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-
546 AM EDT FRI MAY 8 2009

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

.DAY ONE...TODAY AND TONIGHT.

THUNDERSTORMS ARE IN THE FORECAST TODAY AND TONIGHT. THERE IS A
SLIGHT RISK THAT SOME OF THE THUNDERSTORMS COULD BECOME SEVERE...
PRODUCING LARGE HAIL AND DAMAGING WIND.

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

THUNDERSTORMS ARE IN THE FORECAST FROM SATURDAY THROUGH MONDAY...
WITH A DECREASING TREND IN NORTH CAROLINA ON SUNDAY AND MONDAY.
ISOLATED SEVERE STORMS...WITH LARGE HAIL AND DAMAGING WIND ARE
POSSIBLE EACH DAY.

.SPOTTER INFORMATION STATEMENT...

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

NCZ035-056-068>072-082-502-504-SCZ007>009-012>014-091015-
ALEXANDER-CATAWBA-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-
UNION NC-GREATER CALDWELL-GREATER BURKE-SPARTANBURG-CHEROKEE-YORK-
LAURENS-UNION SC-CHESTER-
546 AM EDT FRI MAY 8 2009

...DENSE FOG ADVISORY IN EFFECT UNTIL 9 AM EDT THIS MORNING...

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

.DAY ONE...TODAY AND TONIGHT.

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

   DENSE FOG ADVISORY.

THUNDERSTORMS ARE IN THE FORECAST TODAY AND TONIGHT. ISOLATED SEVERE
THUNDERSTORMS PRODUCING LARGE HAIL AND DAMAGING WIND ARE POSSIBLE.

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

THUNDERSTORMS ARE IN THE FORECAST FROM SATURDAY THROUGH MONDAY...
WITH A DECREASING TREND IN NORTH CAROLINA ON SUNDAY AND MONDAY.
ISOLATED SEVERE STORMS...WITH LARGE HAIL AND DAMAGING WIND ARE
POSSIBLE EACH DAY.

.SPOTTER INFORMATION STATEMENT...

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

GAZ018-026-028-029-NCZ036-037-057-506-508-510-SCZ004>006-010-011-019-
091015-
STEPHENS-FRANKLIN-HART-ELBERT-IREDELL-DAVIE-ROWAN-EASTERN MCDOWELL-
GREATER RUTHERFORD-EASTERN POLK-GREATER OCONEE-GREATER PICKENS-
GREATER GREENVILLE-ANDERSON-ABBEVILLE-GREENWOOD-
546 AM EDT FRI MAY 8 2009

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

.DAY ONE...TODAY AND TONIGHT.

THUNDERSTORMS ARE IN THE FORECAST TODAY AND TONIGHT. ISOLATED SEVERE
THUNDERSTORMS PRODUCING LARGE HAIL AND DAMAGING WIND ARE POSSIBLE.

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

THUNDERSTORMS ARE IN THE FORECAST FROM SATURDAY THROUGH MONDAY...
WITH A DECREASING TREND IN NORTH CAROLINA ON SUNDAY AND MONDAY.
ISOLATED SEVERE STORMS...WITH LARGE HAIL AND DAMAGING WIND ARE
POSSIBLE EACH DAY.

.SPOTTER INFORMATION STATEMENT...

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

07

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
832 AM EDT FRI MAY 8 2009

NCZ051-052-058-081330-
GRAHAM-HAYWOOD-SWAIN-
832 AM EDT FRI MAY 8 2009

...STRONG THUNDERSTORMS WILL AFFECT GRAHAM...NORTHWESTERN HAYWOOD AND
SWAIN COUNTIES THROUGH 930 AM EDT...

AT 832 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM 6 MILES SOUTH OF NEW
MARKET TO 14 MILES SOUTHWEST OF TAPOCO...MOVING EAST AT 40 MPH.

* OTHER LOCATIONS AFFECTED INCLUDE BUT ARE NOT LIMITED TO SANTEETLAH
  LAKE...FONTANA LAKE...WESSER...WATERVILLE...TAPOCO...STECOAH...
  SMOKEMONT...SANTEETLAH...ROBBINSVILLE...NEWFOUND GAP...LUADA...
  FONTANA VILLAGE...CHEROKEE...BRYSON CITY...ALMOND AND ALARKA.

WIND GUSTS OF 40 TO 50 MPH ARE EXPECTED WITH THESE STORMS. INTENSE
LIGHTNING MAY ALSO OCCUR WITH THIS STORM. IF OUTDOORS...STAY AWAY
FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF POSSIBLE.
WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID USING
TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY
ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES.

HG