Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
438 PM EDT TUE JUL 24 2012

.SYNOPSIS...
A WEAK UPPER LEVEL RIDGE WILL BUILD ACROSS THE REGION TONIGHT AND
PERSIST THROUGH THURSDAY. A COLD FRONT IS THEN EXPECTED TO MOVE
ACROSS THE CAROLINAS AND NORTHEAST GEORGIA ON LATE FRIDAY INTO
SATURDAY. ANOTHER RIDGE OF HIGH PRESSURE BUILDS BACK IN SUN AND
REMAINS THROUGH EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 420 PM...THE MCS MOVING SOUTH INTO NORTHEAST TENN/NORTHWEST NC
CONTINUES TO LOSE SOME STEAM AS IT ENCOUNTERS HIGHER STABILITY OVER
THESE AREAS...THE RESULT OF AN OUTFLOW BOUNDARY THAT MOVED THROUGH
THE AREA EARLIER TODAY. MEANWHILE...DENSE CIRRUS CANOPY AHEAD OF THE
MCS TO OUR NORTH IS PREVENTING MUCH IN THE WAY OF AIR MASS RECOVERY.
AS SUCH...I FEEL THAT THE SEVERE WEATHER THREAT IS DIMINISHING
ACROSS THE NC FOOTHILLS AND PIEDMONT ATTM. HOWEVER...THE AIR MASS
OVER THE CENTRAL/SOUTHERN MTNS IS STILL VERY UNSTABLE. THEREFORE...
I WOULD NOT BE SURPRISED IF THE OUTFLOW REINVIGORATES OVER THIS AREA
EARLY THIS EVENING. ANOTHER POSSIBLE AREA FOR SEVERE CONVECTION WILL
BE ACROSS THE UPSTATE AND NORTHEAST GEORGIA...WHERE THE AIR MASS IS
ALSO QUITE UNSTABLE. HOWEVER...WITH THE WEAK SHEAR IN PLACE ACROSS
THIS AREA...ANY SEVERE WEATHER IS EXPECTED TO BE MORE PULSE IN
NATURE.

LATER TONIGHT A WEAK SFC BNDRY WILL MOVE IN FROM THE NORTHEAST. OR
IT MAY SIMPLY BE A MODEL REFLECTION OF EXTENSIVE OUTFLOW BNDRYS.
EITHER WAY...THE NAM KEEPS QUITE A BIT OF CAPE OVER THE REGION
TONIGHT...AND SHRA/TSTMS MAY PERSIST IN SPOTS MUCH OF THE NIGHT. THE
BEST CHANCES WILL PROBABLY BE ALONG THE TN LINE WHERE NW FLOW WILL
GIVE AN OROGRAPHIC BOOST TO CONVECTION. IN THESE AREAS I/VE
MAINTAINED CHANCE POPS THROUGH THE NIGHT...THOUGH ELSEWHERE I TAKE
THEM INTO THE SLIGHT CHANCE RANGE AFTER THE INITIAL ROUNDS OF
CONVECTION.

THE NAM POOLS HIGH DEWPOINTS AND QUITE A BIT OF CAPE OVER THE FA ON
WEDNESDAY. SPC HAS PLACED THE REGION UNDER A 5 PERCENT SEVERE RISK.
THE DEEP LAYER RIDGE WILL TRY TO NOSE BACK INTO THE FA...BUT THE
AMOUNT OF INSTABILITY AND WEAK SFC CONVERGENCE SHOULD SUPPORT GOOD
CONVECTIVE COVERAGE OVER THE WESTERN CAROLINAS AND NE GA DURING THE
AFTN HOURS. SOME OF THESE WILL PROBABLY REACH PULSE SEVERE LIMITS
WITH SMALL AREAS OF WIND DAMAGE AND LARGE HAIL. MAX TEMPS WILL RUN A
COUPLE CATEGORIES ABOVE NORMAL.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 220 PM EDT TUESDAY...SHORT RANGE MODELS INDICATE THAT THE MID
LEVEL RIDGE WILL BUILD OVER THE REGION ON THURSDAY. H85 TEMPS WITHIN
THE LEE OF THE MOUNTAINS INCREASE TO AROUND 24C DURING THE
AFTERNOON. A WEAK SUBSIDENCE IS EXPECTED TO DEVELOP BETWEEN H7 TO
H8...YIELDING AN SHALLOW LAYER OF CIN BETWEEN 10 TO 30 J/KG. IT
APPEARS THAT WEAK LEE TROF MAY DEEPEN SLIGHTLY WITH WEST H85
FLOW...BUT SFC MOISTURE CONVERGENCE SHOULD REMAIN WEAK. COVERAGE OF
DIURNAL CONVECTION SHOULD BE LIMITED BY AFTERNOON MIXING OF SFC
DEWPOINTS AND PERSISTENT WEAK CAPPING. I WILL FORECAST MID AFTERNOON
INITIATION ACROSS THE RIDGES...WITH CHC POPS INTO THE EARLY EVENING.
COVERAGE EAST OF THE MTNS SHOULD REMAIN LIMITED TO A SCHC. THE MAIN
CONCERN ON THURSDAY WILL BE THE HOT AFTERNOON TEMPERATURES. USING A
BLEND OF MOS...HIGH TEMPERATURES ARE FORECAST TO RANGE FROM AROUND
90 WITHIN THE MTN VALLEYS TO U90S EAST...3 TO 5 DEGREES LOWER THAN
RECORDS. HOWEVER...EVEN WITH MIXING DEWPOINTS...HEAT INDEX VALUES
NEAR THE CLT METRO MAY MEET HEAT ADVISORY CRITERIA.

ON FRIDAY...A WEAK COLD FRONT IS EXPECTED TO MOVE ACROSS THE
SOUTHERN APPALACHIANS DURING THE AFTERNOON. THE ENVIRONMENT AHEAD OF
THE FRONT IS EXPECTED TO DEVELOP CAPE VALUES BETWEEN 1500 TO 2000
J/KG WITH LITTLE TO NO CIN. IN ADDITION...UPPER DIVERGENCE MAY
DEVELOP OVER THE REGION AS THE CORE OF A H3 JET PUSHES ACROSS PA.
GIVEN THE APPROACH OF THE SFC FRONT...WIDESPREAD INSTABILITY...AND
UPPER SUPPORT...I WILL FORECAST LIKELY POPS ACROSS THE MTNS AND 30
TO 40 POPS EAST. SEVERE MULTICELL THUNDERSTORMS MAY DEVELOP ALONG
AND AHEAD OF THE FRONT.

HEAT WILL REMAIN A CONCERN ACROSS THE PIEDMONT AS DEWPOINTS RECOVER
TO THE U60S AND HIGHS ONCE AGAIN REACH INTO THE U90S. HEAT INDEX
VALUES ALONG AND EAST OF I-85 MAY REACH HEAT ADVISORY CRITERIA.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 2 PM EDT TUESDAY...THE LATEST MEDIUM RANGE MODELS CONTINUE TO
INDICATE THAT A COLD FRONT WILL MOVE ACROSS THE AREA ON LATE FRI/SAT
AS AN UPPER TROF DEEPENS OVER THE EAST COAST. THE FRONT IS EXPECTED
TO STALL OVER SOUTH OF THE AREA SUN AND DISSIPATES MON AS A RIDGE
BUILDS IN FROM THE SE. THE STRONGEST UPPER FORCING WILL REMAIN NORTH
OF THE AREA...HOWEVER GOOD OVERALL DYNAMICAL LIFT AND H3 DIV ALONG
WITH PLENTY OF LLVL INSTABILITY WILL BE AVAILABLE FOR SCATTERED
DIURNAL TSTMS EACH DAY THROUGH THE PERIOD. POPS WERE MAINTAINED AT
NEAR CLIMO...HOWEVER IF THIS PATTERN AND S/W TIMING PERSISTS OVER
THE NEXT COUPLE MODEL RUNS...AN INCREASE IN POPS WILL BE WARRANTED
FOR FRI/SAT. SUN LOOKS TO BE THE DRIEST DAY WITH FAIRLY STRONG HIGH
PRESSURE BUILDING IN...YET THE FRONT WILL REMAIN JUST TO THE
SOUTH...SO SLIGHT CHANCE POPS WERE MENTIONED THROUGH THE DAY. MON
WILL BE ACTIVE AGAIN AS ANOTHER SHOT OF UPPER ENERGY ROUNDS THE WRN
RIDGE AND TRAVERSES THE REGION. TEMPERATURES WILL BE NEAR...OR A
COUPLE DEGREES ABOVE NORMAL FRI/SAT. WITH NW/LY FLOW SETTING UP
SUN...EXPECT A COUPLE DEGREES COOLER IN THE MTNS SUN/MON. YET...A
GOOD DOWNSLOPE WARMING COMPONENT WILL ENABLE MAXES RIGHT AROUND
NORMAL OVER THE LOWER PIEDMONT.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
AT KCLT...HAVE HELD ON TO TEMPO GROUP FOR CONVECTION FROM 20-22 UTC
THIS AFTN. TSTMS ARE MOVING INTO THE NC MTNS ATTM. HOWEVER...THEY
HAVE LOST SOME OF THEIR ORGANIZATION. I STILL THINK THEY WILL
ORGANIZE AS THEY EMERGE INTO THE FOOTHILLS AND CONFIDENCE IS STILL
GOOD IN A SQUALL LINE LATER IN THE AFTN. WINDS WILL PROBABLY AVERAGE
FROM THE WNW THE REST OF THE AFTN...THOUGH THEY MAY BACK TO THE WSW
AT TIMES. THEY WILL TURN MORE OUT OF THE NORTH BEHIND A WEAK COLD
FRONT LATE TONIGHT. WHILE NOTHING HAS BEEN CARRIED IN THE
TAF...THERE ARE INDICATIONS THAT SHRA/TSTM ACTIVITY COULD BE IN THE
VCNTY MUCH OF THE NIGHT.

ELSEWHERE...SCT TSTMS WILL CONTINUE TO DEVELOP ACROSS THE REGION
THIS AFTN. A STRONG SQUALL LINE IS EXPECTED TO DROP ACROSS THE
REGION THIS EVENING. FOR NOW I/M JUST GOING TO CARRY VCTS FOR
SEVERAL HOURS...BUT AS THE LINE GETS CLOSER WE SHOULD BE ABLE TO ADD
A PERIOD OF TEMPO OR PREVAILING THUNDER. A WEAK COLD FRONT WILL
STALL OVER THE REGION LATE TONIGHT...AND THIS MAY ALLOW SCT
SHRA/TSTMS TO LAST INTO THE MORNING HOURS...THOUGH FOR NOW THAT
HASN/T BEEN CARRIED IN THE TAF. WINDS WILL BE WSW TO W OVER THE
UPSTATE AND NW OVER WRN NC. WINDS LATER TONIGHT WILL BECOME LIGHT OR
SHIFT TO LIGHT OUT OF THE NORTH BEHIND THE FRONT AND THUNDERSTORM
COMPLEXES.

OUTLOOK...EXPECT SOLID CHC CONVECTION WED AFTERNOON AND EVENING.
BEST CHC OF OVERNIGHT RESTRICTIONS WILL BE IN AREAS THAT SEE LOCALLY
HEAVY RAIN. A COLD FRONT MAY BRING MORE WIDESPREAD CONVECTION FRI
AND FRI NIGHT.

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...JPT
NEAR TERM...JDL/MCAVOY
SHORT TERM...NED
LONG TERM...JOH
AVIATION...MCAVOY

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
235 PM EDT TUE JUL 24 2012

NCZ033-050-241915-
AVERY-MITCHELL-
235 PM EDT TUE JUL 24 2012

...A STRONG THUNDERSTORM WILL AFFECT AVERY AND EASTERN MITCHELL
COUNTIES THROUGH 315 PM EDT...

AT 234 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 4 MILES SOUTH OF HAMPTON...OR 8 MILES SOUTH OF
ELIZABETHTON...MOVING SOUTHEAST AT 10 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  BULADEAN...

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

LAT...LON 3615 8181 3611 8180 3609 8176 3599 8188
      3599 8191 3586 8205 3613 8228 3617 8220
      3615 8218 3615 8215 3611 8212 3611 8208
      3613 8203 3623 8196

07

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
434 PM EDT TUE JUL 24 2012

NCZ049-050-242115-
MITCHELL-YANCEY-
434 PM EDT TUE JUL 24 2012

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN YANCEY AND WESTERN
MITCHELL COUNTIES THROUGH 515 PM EDT...

AT 430 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES SOUTHEAST OF LIMESTONE COVE...OR 10 MILES
EAST OF ERWIN...MOVING SOUTH AT 10 MPH.

SMALL HAIL...AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS
STORM.

FREQUENT LIGHTNING IS OCCURRING WITH THIS STORM. IF OUTDOORS...TRY TO
GET INDOORS OR INTO A HARD TOPPED VEHICLE. OTHERWISE...STAY AWAY FROM
OPEN AREAS AND ISOLATED HIGH OBJECTS SUCH AS TREES. WHEN INDOORS...
STAY AWAY FROM WINDOWS AND DOORS AND AVOID USING WIRED ELECTRONIC
DEVICES. TRY TO UNPLUG UNNECESSARY APPLIANCES BEFORE THE STORM
APPROACHES.

LAT...LON 3615 8218 3615 8215 3615 8214 3611 8212
      3588 8214 3592 8244 3612 8237 3614 8230
      3614 8225 3617 8222

KRENTZ

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
452 PM EDT TUE JUL 24 2012

SCZ014-242115-
CHESTER-
452 PM EDT TUE JUL 24 2012

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN CHESTER COUNTY
THROUGH 515 PM EDT...

AT 450 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR FORT LAWN...OR 8 MILES SOUTHWEST OF
LANCASTER...MOVING SOUTHEAST AT 10 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  FISHING CREEK RESERVOIR...
  GREAT FALLS RESERVOIR...

PEOPLE IN SOUTHEASTERN CHESTER COUNTY...INCLUDING THE FOLLOWING
LOCATIONS...

FORT LAWN...FISHING CREEK RESERVOIR...GREAT FALLS RESERVOIR...GREAT
FALLS AND CEDAR CREEK RESERVOIR...

SHOULD MONITOR THE WEATHER SITUATION CLOSELY. LISTEN FOR POSSIBLE
WARNINGS AND BE PREPARED TO TAKE APPROPRIATE ACTION SHOULD SEVERE
WEATHER THREATEN.

PEA SIZE HAIL AND WIND GUSTS OF 40 TO 50 MPH ARE EXPECTED WITH THIS
STORM.

LAT...LON 3467 8088 3465 8089 3455 8087 3454 8088
      3454 8092 3469 8099 3474 8087 3474 8086
      3470 8085

NED