Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
816 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/...
JUST A QUICK UPDATE WAS SENT TO REMOVE MENTION OF HEAT ADVSRY.

PREVIOUS DISCUSSION...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 /00Z MONDAY THROUGH FRIDAY/...
AT KCLT AND ELSEWHERE...CB WILL BE CARRIED ALL TERMINALS UNTIL 01Z
WHEN COOLING SHOULD WEAKEN CONVECTION. CLEARING OVERNIGHT WITH MVFR
FOG KAVL. EXPECT W-NW WINDS KCLT...W ELSEWHERE EXCEPT NW KAVL.
INCLUDED CB CLOUDS AFTER 17-18Z MON AS ISOLD TSTMS RETURN WITH
HEATING...SCT TSTMS MTNS.

OUTLOOK...MOISTURE WILL GRADUALLY DIMINISH EARLY NEXT WEEK IN
PERSISTENT WESTERLY FLOW. STILL EXPECT ISOLD-SCT SHWRS/TSTMS THRU
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...NONE.
SC...NONE.

&&

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

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

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-090015-
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-
812 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.

ISOLATED TO SCATTERED THUNDERSTORMS WILL TAPER OFF BY MID EVENING.

.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
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

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

GAZ018-026-028-072345-
FRANKLIN-HART-STEPHENS-
720 PM EDT SUN AUG 7 2011

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN FRANKLIN...
NORTHWESTERN HART AND SOUTHEASTERN STEPHENS COUNTIES THROUGH 745 PM
EDT...

AT 717 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR AVALON...OR 9 MILES NORTH OF CARNESVILLE...
MOVING EAST AT 25 MPH.

THIS STORM WILL AFFECT LOCATIONS NEAR...
  WHITWORTH...

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

LAT...LON 3431 8301 3448 8329 3455 8323 3452 8308
      3450 8307 3450 8306 3447 8301 3449 8294
      3449 8293 3448 8292

LANE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
734 PM EDT SUN AUG 07 2011

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

0730 PM     HAIL             3 E SPARTANBURG         34.94N 81.88W
08/07/2011  E0.88 INCH       SPARTANBURG        SC   TRAINED SPOTTER

            SPOTTER REPORTS HAIL RANGING FROM PEA TO NICKEL SIZE.

&&

BSH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
753 PM EDT SUN AUG 07 2011

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

0725 PM     HAIL             3 NE SPARTANBURG        34.98N 81.89W
08/07/2011  E0.88 INCH       SPARTANBURG        SC   TRAINED SPOTTER

&&

BSH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
836 PM EDT SUN AUG 07 2011

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

0831 PM     HAIL             3 NNW UNION             34.76N 81.64W
08/07/2011  E1.00 INCH       UNION              SC   FIRE DEPT/RESCUE

            FD OFFICIAL/SPOTTER REPORTED QUARTER SIZE HAIL AND 50 MPH
            WIND GUST.

&&

LANE

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

SCZ014-080130-
CHESTER-
838 PM EDT SUN AUG 7 2011

...A STRONG THUNDERSTORM WILL AFFECT WESTERN CHESTER COUNTY THROUGH
930 PM EDT...

AT 833 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES SOUTH OF LOCKHART...OR 10 MILES EAST OF
UNION...MOVING SOUTHEAST AT 15 MPH.

THIS STORM WILL AFFECT LOCATIONS NEAR...
  CHESTER...

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

LAT...LON 3466 8145 3470 8146 3472 8145 3473 8149
      3474 8149 3476 8145 3480 8147 3481 8146
      3478 8112 3456 8128

LANE