Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
229 PM EDT SUN AUG 7 2011

.SYNOPSIS...
A WEAK FRONT WILL STALL OVER THE MOUNTAINS ON MONDAY AND REMAIN
THERE THROUGH TUESDAY. THE FRONT WILL PUSH SOUTH OF OUR AREA ON
WEDNESDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTH. ANOTHER COLD
FRONT WILL APPROACH THE AREA OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 145 PM...A WEAKENING MCV/VORTMAX CAN BE SEEN ON SATELLITE
IMAGERY OVER ERN TN WITHIN STRENGTHENING WESTERLY FLOW. THE VORT
WILL TRACK THRU THE CWFA THIS EVENING...AND SHUD HELP KICK OFF
CONVECTION LATE THIS AFTN AND EVENING. THE ENVIRONMENT IS VERY MOIST
AND UNSTABLE...WITH A LTL GREATER CAPE AND SHEAR THAN YESTERDAY. THE
GSP VWP SHOWS WEAK WESTERLY LLVL FLOW...WITH NWLY FLOW AT 6000 FT
AND HIGHER. SO HAVE NOT REALLY STARTED MIXING OUT YET...AND DCAPES
ARE STILL RELATIVELY LOW...BUT STILL EXPECTED TO INCREASE. SO SEVERE
THREAT DOES NOT LOOK MUCH HIGHER THAN YESTERDAY AT THE MOMENT. PWATS
STILL RUNNING 150+ PERCENT OF NORMAL. SO EXCESSIVE/HEAVY RAIN IS
STILL A THREAT WITH ANY CONVECTION THAT DOES DEVELOP.

TONIGHT...DRIER MID LVL AIR WILL PUSH IN BEHIND THE WEAK
VORTMAX...AS WESTERLY 700 MB FLOW STRENGTHENS TO 25-35 KTS. SKIES
SHOULD CLEAR OUT SAVE FOR SOME LINGER CIRRUS...AND POPS QUICKLY
TAPER TO BELOW 15 PERCENT. LOWS WILL BE IN THE 60S MTNS AND LWR-MID
70S PIEDMONT.

MONDAY...FOR THE BULK OF THE DAY THE CWFA WILL BE WITHIN RELATIVELY
DRIER WESTERLY FLOW...WITH A RIPPLE OF SHORTWAVE RIDGING ALOFT AND
LLVL DOWNSLOPE. SO A LATER START TO CONVECTION WITH COVERAGE
GENERALLY WIDELY SCATTERED MTNS AND ISOLATED PIEDMONT. STEEPER LLVL
LAPSE RATES AND DRY MID LVLS WILL LIKELY RESULT IN A HIGHER
PERCENTAGE OF STORMS TO PRODUCE DOWNBURSTS. BUT NOT EXPECTING
ANYTHING ORGANIZED. TEMPS WILL BE QUITE WARM WITH MORE INSOLATION
AND DOWNSLOPE (80S TO LWR 90S MTN VLYS AND GENERALLY UPR 90S TO 100
PIEDMONT).

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 215 PM SUNDAY...AN UPPER LEVEL SHORTWAVE ROUNDING A VIGOROUS
SRN CANADIAN TROUGH WILL INTERACT WITH A COLD FRONT IN PLACE ACROSS
THE LOWER OH VALLEY MON NIGHT TO LIKELY TRIGGER CONVECTION THERE.
THE RESULTING MCS SHOULD MAKE A RUN TOWARD THE SRN APPALACHIANS
DURING THE EARLY MORNING HOURS TUE. THERE REMAINS CONSIDERABLE
QUESTION ABOUT WHETHER THE MCS WILL REACH OUR FORECAST ACTIVITY WITH
ANY PUNCH EARLY TUE...AND HOW FAR EAST IT WILL PENETRATE. THE WEAK
INSTABILITY SHOULD LEAD TO A DECAYING SYSTEM REACHING THE NC
MTNS...AND PROBABLY DISSIPATING E OF THE MTN CHAIN TUE MORNING. THE
POP GRIDS WILL REFLECT THIS APPROACH. IN ADDITION...ANOTHER MCS
COULD DEVELOP LATER IN THE DAY ALONG THE TRAILING BOUNDARY IN THE
MID MS VALLEY...AND ALSO MAKE AN EASTWARD RUN THROUGH TUE EVENING.
OTHERWISE...W TO NW DOWNSLOPE FLOW WILL BOOST WARMING E OF THE MTNS.
EARLY DEBRIS CLOUDS AND SLIGHTLY MIXED DEWPOINTS SHOULD KEEP MOST OF
THE AREA BELOW ANY ADVISORY CRITERIA...BUT HEAT INDEX VALUES ABOVE
100 ARE LIKELY IN THE SRN PIEDMONT TUE AFTN.

THE WEAK COLD FRONT UPSTREAM WILL PUSH SE TOWARD THE AREA LATER
TUESDAY NIGHT INTO WED. SOME THICKNESS FALLS ARE INDICATED ACROSS
THE AREA WED AFTN...BUT PERSISTING WEST TO NW DOWNSLOPE FLOW E OF
THE MTNS WILL STILL KEEP TEMPS ABOVE NORMAL. MUCH DRIER AIR SHOULD
ARRIVE IN PROFILES WED...WITH ANY SLIGHT CHANCES FOR CONVECTION
CONFINED MAINLY TO CENTRAL AND NRN MTN LOCATIONS IN THE NW FLOW.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 225 PM SUNDAY...THERE IS GOOD OVERALL AGREEMENT IN THE OP
MODELS AND LITTLE SPREAD SEEN IN THE GFS ENS THROUGH THE EXT RANGE.
THERE ARE SIGNIFICANT DIFFERENCES IN THE SMALLER SCALE AND EVEN THE
TREATMENT/MAGNITUDE OF THE LLVL AIRMASS...BUT THE GENERAL FLOW AND
SYNOPTIC DYNAMICS ALLOW ABOVE AVERAGE CONFIDENCE THROUGH SAT...AND
NORMAL TO BELOW CONFIDENCE AFTER THAT THROUGH MON.

UPPER LEVEL HEIGHTS REMAIN BROAD AND WEAKLY CYCLONIC WITH SMALL
POCKETS OF S/W ENERGY CROSSING THE CWFA THU THROUGH FRI...HOWEVER
MOISTURE WILL BE LOW AS A SFC HIGH BUILDS EAST ACROSS THE OH VALLEY.
A GOOD DEGREE OF INSOLATION AND WEAK AIRMASS MIXING WILL ALLOW TEMPS
TO REACH A FEW DEGREES ABOVE NORMAL...BUT SFC TD/S WILL STILL MIX
OUT INTO THE LOWER TO MID 60S MAKING FOR A RATHER PLEASANT
CONDITIONS BOTH DAYS.

THE MODELS BEGIN TO DIVERGE WITH THE FRONTAL SYSTEM SAT THROUGH THE
PERIOD. BETTER AGREEMENT IS HAD BETWEEN THE CMC AND THE GFS...SO THE
FORECAST WAS CRAFTED WITH A MIX OF THESE IDEAS IN MIND. THERE SHOULD
BE INCREASING MOISTURE FLUX AHEAD OF THE COLD FRONT SAT AND THIS
WILL ENABLE SHOWER ACTIVITY...WITH DEEPER CONVECTION DRIVEN BY
AFTERNOON DESTABILIZATION. DONT ANTICIPATE MUCH IN THE WAY OF A
SEVERE THREAT AS SBCAPE REMAINS SHALLOW AND WEAK WHILE SHEAR DOESNT
INCREASE ABOVE 15 KTS UNTIL H5. THERE WILL BE LINGERING ACTIVITY SUN
AS FROPA LOOKS TO BE BTW 12Z-15Z. THE OVERALL DYNAMICAL SHEAR
INCREASES WITH THE FRONT...BUT AGAIN CAPE WILL BE ON THE LOW END SO
DONT ENVISION MUCH IN THE WAY OF A SEVERE THREAT.

MAX TEMPS SAT AND SUN WILL STILL BE A COUPLE DEGREES ABOVE NORMAL OR
RIGHT AROUND NORMAL...WITH HIGHER TD/S SAT MAKING FOR MORE HUMID
CONDITIONS. THERE WILL BE A DECENT AIRMASS MIX SUN POST FROPA...SO
PLEASANT CONDITIONS WILL BE IN STORE FOR SUN AFTERNOON INTO NEW DAY
7.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
AT KCLT...CUMULUS SLOW TO DEVELOP THIS AFTN...WITH DOWNSLOPE AND
DEEP MIXING OCCURRING EAST OF THE MTNS. WINDS AROUND 290-310 DIR
ALOFT ARE BEING MIXED DOWN...BUT A LEE TROF SHUD CANCEL SOME OF THAT
OUT BY 20-21Z...PERHAPS FAVORING A WSW DIR. SCATTERED TSTMS ARE
STILL EXPECTED LATE AFTN AND INTO THE EVENING. SO KEEP A CB MENTION.
DRIER AIR WILL ADVECT ACRS THE REGION TONIGHT AND MONDAY
MORNING...SO VSBY RESTRICTIONS LOOK DOUBTFUL. A NW WIND WILL LIKELY
BEGIN MIXING DOWN LATE MORNING.

ELSEWHERE...STILL EXPECTING SCATTERED TO NUMEROUS SHWRS AND TSTMS
THIS AFTERNOON...STARTING ACRS THE NC MTNS...AND ENDING BY LATE
EVENING IN THE EAST. SOME LINGERING MID AND HIGH CLOUDS POSSIBLE
OVERNIGHT. NOT EXPECTING MUCH FOG...EXCEPT IN THE MTN VALLEYS.

OUTLOOK...MOISTURE WILL GRADUALLY DIMINISH EARLY NEXT WEEK AS LOW
DUE TO PERSISTENT WESTERLY FLOW. HOWEVER...CHANCES SCATTERED
AFTERNOON/EVENING SHOWERS/TS WILL REMAIN THROUGH THE PERIOD.

AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...

WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NCZ082.
SC...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR SCZ009-011>014-
     019.

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
443 PM EDT SUN AUG 7 2011

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-501>510-SCZ001>008-010-082045-
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-
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-ANDERSON-
443 PM EDT SUN AUG 7 2011

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

.DAY ONE...TONIGHT.

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER
THE REGION LATE THIS AFTERNOON INTO THIS EVENING...MAINLY OVER THE
MOUNTAINS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

A COLD FRONT WILL MOVE INTO THE MOUNTAINS DURING THE DAY ON MONDAY.
SCATTERED THUNDERSTORMS ARE EXPECTED ALONG AND AHEAD OF THE FRONT.
SOME OF THE THUNDERSTORMS MAY BECOME SEVERE AND PRODUCE DAMAGING
WINDS LATE MONDAY OR MONDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

NONE.

NCZ082-SCZ009-011>014-019-082045-
UNION NC-YORK-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
443 PM EDT SUN AUG 7 2011

...HEAT ADVISORY IN EFFECT UNTIL 8 PM EDT THIS EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PIEDMONT 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.

   HEAT ADVISORY.

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER
THE REGION LATE THIS AFTERNOON INTO THIS EVENING...MAINLY OVER THE
MOUNTAINS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

A COLD FRONT WILL MOVE INTO THE MOUNTAINS DURING THE DAY ON MONDAY.
SCATTERED THUNDERSTORMS ARE EXPECTED ALONG AND AHEAD OF THE FRONT.
SOME OF THE THUNDERSTORMS MAY BECOME SEVERE AND PRODUCE DAMAGING
WINDS LATE MONDAY OR MONDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

NONE.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
550 PM EDT SUN AUG 7 2011

NCZ508-072215-
GREATER RUTHERFORD-
550 PM EDT SUN AUG 7 2011

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN RUTHERFORD COUNTY
THROUGH 615 PM EDT...

AT 545 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 4 MILES NORTHWEST OF HARRIS...OR 6 MILES SOUTH OF
RUTHERFORDTON...MOVING EAST AT 25 MPH.

THIS STORM WILL BE AFFECT LOCATIONS NEAR...
  CLIFFSIDE...

WIND GUSTS OF 40 TO 50 MPH ARE EXPECTED WITH THIS STORM.

LAT...LON 3523 8176 3518 8177 3518 8180 3522 8196
      3525 8196 3527 8199 3532 8199 3532 8172

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
615 PM EDT SUN AUG 7 2011

NCZ068-072245-
CLEVELAND-
615 PM EDT SUN AUG 7 2011

...A STRONG THUNDERSTORM WILL AFFECT SOUTHWESTERN CLEVELAND COUNTY
THROUGH 645 PM EDT...

AT 610 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR MOORESBORO...OR 11 MILES WEST OF SHELBY...
MOVING EAST AT 25 MPH.

THIS STORM WILL AFFECT LOCATIONS NEAR...
  BOILING SPRINGS NC...
  SHELBY...

WIND GUSTS OF 40 TO 50 MPH ARE EXPECTED WITH THIS STORM.

LAT...LON 3518 8152 3525 8175 3526 8175 3533 8171
      3533 8148

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
636 PM EDT SUN AUG 7 2011

SCZ007-072300-
SPARTANBURG-
636 PM EDT SUN AUG 7 2011

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN SPARTANBURG COUNTY
THROUGH 700 PM EDT...

AT 631 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR LAKE BOWEN...OR 11 MILES SOUTHEAST OF
COLUMBUS...MOVING EAST AT 25 MPH.

THIS STORM WILL BE AFFECT LOCATIONS NEAR...
  CHESNEE...
  MAYO...

WIND GUSTS OF 40 TO 50 MPH ARE EXPECTED WITH THIS STORM.

LAT...LON 3511 8212 3518 8210 3518 8187 3505 8180
      3504 8181 3504 8180 3501 8178

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
647 PM EDT SUN AUG 7 2011

SCZ008-072315-
CHEROKEE-
647 PM EDT SUN AUG 7 2011

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN CHEROKEE COUNTY
THROUGH 715 PM EDT...

AT 639 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR CHESNEE...OR 12 MILES WEST OF GAFFNEY...
MOVING SOUTHEAST AT 20 MPH.

THIS STORM WILL AFFECT LOCATIONS NEAR...
  THICKETTY...
  GAFFNEY...

WIND GUSTS OF 40 TO 50 MPH ARE EXPECTED WITH THIS STORM.

LAT...LON 3497 8167 3505 8181 3508 8181 3510 8184
      3517 8187 3514 8163

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
707 PM EDT SUN AUG 7 2011

NCZ058-072345-
GRAHAM-
707 PM EDT SUN AUG 7 2011

...A STRONG THUNDERSTORM WILL AFFECT GRAHAM COUNTY THROUGH 745 PM
EDT...

AT 700 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR TAPOCO...OR 11 MILES NORTHWEST OF
ROBBINSVILLE...MOVING SOUTHEAST AT 20 MPH.

THIS STORM WILL AFFECT LOCATIONS NEAR...
  FONTANA VILLAGE...
  SANTEETLAH LAKE...
  ROBBINSVILLE...

WIND GUSTS OF 40 TO 50 MPH ARE EXPECTED WITH THIS STORM.

LAT...LON 3546 8396 3545 8393 3547 8390 3538 8361
      3533 8365 3532 8369 3529 8369 3526 8371
      3524 8387 3538 8402 3540 8403

LANE