Hail and Damaging Winds in North Carolina, September 2, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
207 PM EDT FRI SEP 2 2011

.SYNOPSIS...
A RIDGE OF WEAK HIGH PRESSURE WILL REMAIN ENTRENCHED ACROSS THE
SOUTHEAST AND DOMINATE OUR WEATHER PATTERN THROUGH SUNDAY. A COLD
FRONT WILL THEN MOVE OVER THE CAROLINAS BY LABOR DAY AND STALL OUT
THROUGH THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
ISOLATED CONVECTION HAS DEVELOPED AS EXPECTED ACROSS THE HIGHER
TERRAIN. HOWEVER...THE CU FIELD OVER THE NC PIEDMONT (WHERE WE HAVE
THE HIGHEST POPS THIS AFTERNOON) IS VERY UNINSPIRING.
NEVERTHELESS...THE ATMOSPHERE IS QUITE UNSTABLE ALONG/NORTH OF I-40
(2500 TO 3500+ J/KG) AND CONVECTION IS BEGINNING TO FIRE UPSTREAM
ALONG THE BLUE RIDGE IN VIRGINIA. THEREFORE...IT STILL APPEARS THAT
HEALTHY CHANCE POPS ARE WARRANTED ACROSS THE PIEDMONT...WITH SLIGHT
CHANCES SUFFICING OVER THE MTNS. ALTHOUGH FREEZING LEVELS ARE QUITE
HIGH OVER THE REGION...DOWNDRAFT CAPE IS ALSO VERY HIGH...ESP OVER
THE NC PIEDMONT. THERE SHOULD BE AN ENHANCED RISK FOR ISOLATED
MICROBURSTS WITH THE STORMS THIS AFTERNOON/EARLY EVENING.
OTHERWISE...ITS A HOT AFTERNOON...AS ALL AREAS BELOW ABOUT 2500 FEET
WERE IN THE 90S AS OF 18Z. BY 5 PM...TEMPS SHOULD RANGE FROM THE
LOWER 90S IN THE LOWER MTN VALLEYS...TO UPPER 90S ACROSS THE
WESTERN/CTRL UPSTATE.

FOR TONIGHT...ANY ONGOING CONVECTION SHOULD WEAKEN THROUGH LATE
EVENING...AFTER WHICH EXPECT A QUIET NIGHT WITH THE WEAK LOW
DRIFTING TO THE SW OVER THE UPSTATE. MIN TEMPS CLOSE TO A GUIDANCE
BLEND.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...THE SHORT TERM FCST BEGINS AT 12 ON SATURDAY
WITH THE CLOSED UPPER LOW DEEPENING OVER THE NORTHERN GULF OF MEXICO
JUST SOUTH OF LOUISIANA AND A FLAT UPPER RIDGE OVER THE EASTERN
CONUS. OVER THE NEXT 24 HRS OR SO...THIS RIDGE WEAKENS AS A NORTHERN
STREAM UPPER TROF APPROACHES FROM THE NW AND BEGINS TO INTERACT WITH
THE GOM CLOSED LOW. LATEST RUNS OF THE NAM AND GFS HAVE THE TROF
ROUGHLY IN PHASE WITH THE CLOSED LOW BY THE END OF THE PERIOD AT 12Z
ON MON.

ON SATURDAY...WEAKENING SFC HIGH PRESSURE WILL CAUSE BOUNDARY LAYER
FLOW TO BECOME SOUTHEASTERLY BY SAT EVENING AND REMAIN SOUTHERLY
THRU THE REMAINDER OF THE PERIOD. INCREASING UPSLOPE MOIST FLOW WILL
INCREASE POPS INTO SUN AS A STRONG FRONTAL BOUNDARY APPROACHES FROM
THE NW CREATING A BROAD REGION OF LOW LVL CONVERGENCE OVER THE AREA.
FOR SUNDAY THRU EARLY MONDAY...THE SFC FRONT WILL STRENGTHEN AND MOVE
CLOSER TO THE FCST AREA...BUT IS NOT EXPECTED TO PUSH THROUGH UNTIL
SOMETIME EARLY MONDAY INTO THE MEDIUM RANGE PERIOD. WITH THE NEARLY
STATIONARY TROPICAL LOW TO OUR SW AND THE FRONT TO OUR NW...A
SCENARIO IS SETTING UP THAT COULD PRODUCE SIGNIFICANT AMOUNTS OF
RAINFALL THRU THE REMAINDER OF THE PERIOD. LATEST MODEL SOUNDINGS
HAVE PWAT VALUES AROUND 2 INCHES FROM LATE SUN ONWARD WITH
MOIST...TROPICAL PROFILES. OBVIOUSLY...THE POTENTIAL FOR WIDESPREAD
FLOODING WILL HAVE TO BE WATCHED CAREFULLY OVER THE NEXT 24 TO 48HRS.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 330 AM FRIDAY...THE MEDIUM RANGE FCST PICKS UP AT 12Z ON MONDAY
WITH THE UPPER TROF DIGGING DOWN OVER THE OHIO RIVER VALLEY/GREAT
LAKES REGION AS THE CLOSED UPPER LOW OVER THE NORTHERN GULF OF
MEXICO OPENS UP AND BEGINS TO BE ABSORBED BY THE NORTHERN STREAM
FLOW. THE LATEST LONG RANGE MODEL RUNS CONTINUE TO SUGGEST THAT THE
CLOSED UPPER LOW WILL MAINTAIN SOME DEGREE OF SOUTHERN STREAM
TROFINESS THRU DAY 7. AT THE SFC...WE CAN EXPECT HEAVY AND
PERSISTENT PERIODS OF RAINFALL AS A SIGNIFICANT FRONTAL BOUNDARY
MOVES INTO THE CWFA FROM THE NW. THE STRONG SFC HIGH BEHIND THE
FRONT IS EXPECTED TO KEEP THE SFC LOW OVER THE NORTHERN GULF OF
MEXICO/SOUTHERN SE CONUS FOR THRU AT LEAST DAY 5 AND LIKELY LONGER.
BEYOND THAT...DEGRADATION OF THE LOW IS UNCLEAR AT THIS POINT
WITH THE MODELS DIVERGING CONSIDERABLY. FOR THE SENSIBLE
FCST...STEADY RAINFALL THRU AT LEAST WED IS LOOKING MORE LIKELY. THE
LATEST RUN OF THE GFS DEEPENS TS KATIA FASTER AS IT APPROACHES THE
SE CONUS PRODUCING MORE WRAP AROUND MOISTURE THRU DAY 7 WHILE THE
OLDER RUN OF THE ECMWF PUSHES THE SFC RIDGE FARTHER EAST AND SOUTH
PUTTING THE FCST AREA IN DRIER NLY DOWNSLOPE FLOW BY MIDDAY THURS.
WILL GO WITH A BLEND OF THE 2 SOLUTIONS FOR DAYS 6 AND 7 FOR NOW AND
KEEP AT LEAST A CHANCE POP IN THE FCST. I EXPECT TEMPS TO REMAIN
BELOW CLIMATOLOGY THRU DAY 7.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT AND KHKY...THE ATMOSPHERE IS DESTABILIZING QUITE STRONGLY
ACROSS THE NC PIEDMONT AND FHILLS THIS AFTERNOON. HOWEVER...THE
CUMULUS FIELD IS NOT ESPECIALLY HEALTHY...SO CONVECTIVE DEVELOPMENT
DOESNT SEEM IMMINENT...BUT I WOULD EXPECT SCATTERED TS ACROSS THE
REGION IN THE 20-22Z TIME FRAME. DUE TO A WEAK LEE TROUGH...WINDS
ARE HIGHLY VARIABLE IN DIRECTION THIS AFTERNOON...BUT THEY SHOULD
REMAIN AT 5 KT OR LESS. CONVECTION WILL PROBABLY LINGER INTO MID-
EVENING...BUT IS EXPECTED TO DIMINISH BY MIDNIGHT. INCREASING
SURFACE MOISTURE SHOULD LEAD TO A BETTER POTENTIAL FOR FOG EARLY
SATURDAY MORNING...AND MVFR CONDITIONS WILL BE FORECAST PRIOR TO
12Z.

ELSEWHERE...ISOLATED CONVECTION WAS DEVELOPING OVER THE HIGHER
TERRAIN EARLY THIS AFTERNOON...INCLUDING ONE CELL JUST A FEW MILES
EAST OF KAVL. THE PERIOD WILL START OUT WITH A CB AT KAVL...ENDING
EARLY THIS EVENING. CONVECTION SHOULD BE VERY ISOLATED AT BEST NEAR
THE UPSTATE TERMINALS...SO NO CB GROUP HAS BEEN INCLUDED ATTM.
OTHERWISE...THERE WILL BE A HIGHER POTENTIAL FOR FOG LATE TONIGHT.
NUMERICAL GUIDANCE IS ONCE AGAIN INSISTING ON DEVELOPMENT OF LIFR
CONDITIONS AT KAVL TONIGHT. GUIDANCE HAS BEEN MUCH TOO PESSIMISTIC
FOR THE PAST SEVERAL DAYS WITH KAVL VISBY. WE HAVE OPTED TO TAKE
CONDITIONS TO 2SM FOR THE TIME BEING. FOR THE UPSTATE TERMINALS...
REDUCED VISBY IS NOT OUT OF THE QUESTION...BUT CONFIDENCE IS TOO LOW
TO INCLUDE IT ATTM.

OUTLOOK...VFR WEATHER EXCEPT OCCASIONAL MORNING VISIBILITY
RESTRICTIONS IN FOG AND HAZE. ON MONDAY...MVFR AND IFR WEATHER IS
POSSIBLE IN SHOWERS AND THUNDERSTORMS AS A COLD FROM ARRIVES FROM
THE NW. THE EARLY PART OF NEXT WEEK MAY SEE EXTENDED PERIODS OF LOW
CLOUDS AND LOW VISIBILITY.

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

&&

.CLIMATE...
GREENVILLE-SPARTANBURG HAS RECORDED A HIGH TEMPERATURE OF 90 DEGREES
OR HIGHER 84 TIMES THIS YEAR AS OF SEPTEMBER 1. THIS TIES THE RECORD
FOR THE GREATEST NUMBER OF DAYS WHERE THE TEMPERATURE HAS REACHED 90
DEGREES OR HIGHER IN ANY YEAR...LAST OCCURRING IN 1954.

&&

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

&&

SYNOPSIS...JPT
NEAR TERM...JDL/PM
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...JDL
CLIMATE...JAT/CSH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
553 AM EDT FRI SEP 2 2011

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-031000-
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-
553 AM EDT FRI SEP 2 2011

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

.DAY ONE...TODAY AND TONIGHT.

ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE LATE THIS
AFTERNOON AND EVENING OVER THE PIEDMONT OF NORTH CAROLINA. THE
MAIN THREATS FROM THESE STORMS WILL BE CLOUD TO GROUND LIGHTNING
AND GUSTY WINDS SOME OF WHICH COULD REACH SEVERE CRITERIA.

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

A COLD FRONT WILL APPROACH THE REGION FROM THE NORTHWEST LATE THIS
WEEKEND AND STALL OUT OVER THE AREA AS A PERSISTENT TROPICAL LOW
PRESSURE SYSTEM LINGERS TO OUR SOUTHWEST. THIS PATTERN HAS THE
POTENTIAL TO PRODUCE LARGE AMOUNTS OF RAINFALL OVER MUCH OF THE
WESTERN CAROLINAS THROUGH THE MIDDLE OF NEXT WEEK, INCREASING THE
POTENTIAL FOR WIDESPREAD FLOODING. SOME UNCERTAINTY STILL EXISTS
WITH RESPECT TO THE EVOLUTION OF THIS PATTERN...THEREFORE THE
FORECAST SHOULD BE CLOSELY MONITORED OVER THE NEXT FEW DAYS.

.SPOTTER INFORMATION STATEMENT...

NONE.

JPT

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
207 PM EDT FRI SEP 2 2011

NCZ053-064-065-SCZ003-021900-
BUNCOMBE-GREENVILLE MOUNTAINS-HENDERSON-TRANSYLVANIA-
207 PM EDT FRI SEP 2 2011

...A STRONG THUNDERSTORM WILL AFFECT EASTERN TRANSYLVANIA...
HENDERSON...NORTHWESTERN GREENVILLE AND SOUTHERN BUNCOMBE COUNTIES
THROUGH 300 PM EDT...

AT 205 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 4 MILES NORTHWEST OF EDNEYVILLE...OR 7 MILES
NORTHEAST OF HENDERSONVILLE...MOVING SOUTHWEST AT 15 MPH.

THIS STORM WILL BE NEAR...
  FLETCHER...
  MOUNTAIN HOME...
  HENDERSONVILLE...
  FLAT ROCK...
  ETOWAH...

PEA SIZE HAIL...AND WIND GUSTS OF 30 TO 40 MPH ARE EXPECTED WITH THIS
STORM.

LAT...LON 3546 8227 3544 8228 3544 8227 3508 8244
      3518 8272 3553 8246

RB