Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
424 PM EDT SUN AUG 5 2012

.SYNOPSIS...
A NEARLY STATIONARY FRONT WILL SLOWLY DRIFT SOUTHEAST FROM TENNESSEE
TONIGHT AND MONDAY AS MOIST TROPICAL AIR MOVES NORTH FROM FLORIDA.
THIS FRONT WILL SLOWLY DISSIPATE LATER IN THE WEEK AS ERNESTO
IMPACTS MEXICO.

&&

.NEAR TERM /THROUGH MONDAY/...
430 PM UPDATE...MADE ADJUSTMENTS TO THE TEMP AND DEWPOINT FIELDS
BASED ON DIFFERENTIAL HEATING AND MIXING. SKY COVER WAS BLENDED WITH
THE LATEST VSBY REPRESENTATION AND MODIFIED THE HR/LY GRIDS
ACCORDINGLY THROUGH 00Z. NO CHANGES NEEDED FOR POPS OR THUNDER.
STILL EXPECT A DIMINISHING TREND OF CONVECTION ACROSS THE NON/MTNS
WITH DRIER AIR MIXING IN FROM THE MID LEVELS AND NEARLY STEADY STATE
CONVECTIVE COVERAGE ACROSS THE NC MTNS OVER THE NEXT 3 HRS.

AS OF 235 PM...HEALTHY CU FIELD ALONG AND EAST OF I-85 WILL COMBINE
WITH AN NORTHWEST TRACKING BOUNDARY FROM THE EAST OVER THE NEXT
SEVERAL HOURS. W/V SHOWS DEEP MOISTURE ALONG THE FL/GA LINE AND
CAROLINA COASTAL PLAIN...SPREADING NW. TO THE WEST...ANOTHER PLUME
OF MOISTURE ASSOCIATED WITH PRE FRONTAL CONVECTION ACROSS KY/TN.
LATEST CAPE ANALYSIS SHOWS A WIDE AREA OF 2000 J/KG ACROSS THE
WESTERN CAROLINAS AND NORTHEAST GEORGIA. CONVECTION SHOULD INCREASE
FROM THE EAST...AS RIDGE TOP CONVECTION INCREASE LATE THIS
AFTERNOON. THIS EVENING...PRE FRONTAL CONVECTION SHOULD PUSH ACROSS
THE SOUTHERN APPALACHIANS...LIKELY DISSIPATING DURING THE LATE
EVENING HOURS. OBSERVED SOUNDINGS AT FFC AND GSO INDICATE THAT STORM
MOTIONS SHOULD REMAIN HIGHER THAN YESTERDAY...POSSIBLE NEAR 10 KTS.
HOWEVER...PW VALUES REMAIN BETWEEN 1.7 TO 2 INCHES. FZL SHOULD
REMAIN AT OR ABOVE 15 KFT WITH LITTLE TO NO DCAPE. IT APPEARS THAT
HEAVY RAIN WILL REMAIN THE MOST LIKELY THREAT WITH SHOWERS AND
THUNDERSTORMS THROUGH THIS EVENING. OVERNIGHT...SHRA AND TSRA WILL
GRADUALLY FADE AFTER SUNSET...LINGERING A LITTLE LATER OVER THE
MTNS. TEMPERATURES SHOULD COOL TO AROUND NORMAL.

MONDAY...A COLD FRONT IS EXPECTED TO ADVANCE OVER THE OHIO RIVER
VALLEY DURING THE EARLY MORNING HOURS...THEN STALLING OVER THE
VIRGINIAS DURING THE AFTERNOON AND EVENING. IN THE MID LEVELS...A S/W
IS EXPECTED TO RIPPLE WEST TO EAST...REACHING THE SOUTHERN
APPALACHIANS DURING THE LATE AFTERNOON. THE AIR MASS WILL REMAIN
VERY MOIST AND MARGINALLY UNSTABLE. THE COMBINATION OF THE SFC
FRONT...MID LEVEL DISTURBANCE...AND WARM AND MOIST ENVIRONMENT
SHOULD RESULT IN GREATER COVERAGE OF SHRA/TSRA THAN TODAY. I WILL
FORECAST HIGH CHC TO LIKELY POPS DURING THE AFTERNOON AND EARLY
EVENING. SEVERE THUNDERSTORMS POTENTIAL APPEARS LOW...WE WILL
CONTINUE TO HIGHLIGHT LOCALIZED HEAVY RAIN IN THE HWO. HIGH
TEMPERATURES SHOULD REMAIN 3 TO 6 DEGREES BELOW NORMAL.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 230 PM EDT SUN...A WEAK TROPICAL LOW WILL DRIFT WESTWARD TO A
POSITION ACROSS SRN AL ON TUE. THIS WILL PUT THE REGION IN A FAIRLY
LIGHT BUT VERY MOIST SLY FLOW. A DIFFUSE SFC FRONT WILL BE LOCATED
ACROSS THE NC MTNS BENEATH AN H5 SHEAR AXIS. THE PATTERN WILL
SUPPORT WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY WELL INTO MONDAY
NIGHT AND AGAIN ON TUE. LOCALIZED VERY HEAVY RAIN WILL BE
POSSIBLE...PARTICULARLY IF ANY SORT OF MCV/S SPIN UP IN THE TROPICAL
AIRMASS AND LOCALLY INCREASE THE LLVL UPSLOPE FLOW AND CONVERGENCE.
THIS POTENTIAL WILL BE HEIGHTENED BY THE ENTRANCE REGION OF THE
UPPER TROPOSPHERIC JET WHICH WILL BE LOCATED JUST NORTH OF THE
REGION MON NIGHT THROUGH WED. ANY SORT OF UPPER DIVERGENCE IN THE
ENTRANCE REGION OF THE JET WILL ALSO INDUCE A LLVL ADJUSTMENT AND
INCREASE THE FLOW OUT OF THE SE...AIDING UPSLOPE AND
CONVERGENCE...SUPPORTING HEAVY RAINFALL

ON WEDNESDAY THE TROPICAL LOW ITSELF WILL BEGIN TO LIFT TO THE NE.
OTHERWISE THE PATTERN IS LARGELY THE SAME WITH THE HIGH PW
AIRMASS...H5 SHEAR AXIS AND STATIONARY FRONT SOMEWHERE ALONG THE
MTNS. THIS WILL YIELD ANOTHER DAY OF WIDESPREAD CONVECTIVE
RAINFALL...WITH THE POTENTIAL ONCE AGAIN FOR LOCALLY VERY HEAVY
RAIN...ESPECIALLY AS THE LOW APPROACHES EITHER LATE WEDNESDAY OR
WEDNESDAY NIGHT. A LOT WILL DEPEND ON THE LOW TRACK AND WHERE THE
STRONGEST LLVL CONVERGENCE SETS UP...BUT FLOODING IS A DISTINCT
POSSIBILITY MON NIGHT INTO WED NIGHT OF NEXT WEEK. THIS WILL BE
HIGHLIGHTED IN THE HWO.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
A DEEP UPPER RIDGE WILL REMAIN PARKED OVER THE INTERMOUNTAIN WEST
FOR THE DURATION OF THE MEDIUM RANGE. A SERIES OF SHORT WAVE WILL
DROP DOWN THE EAST SIDE OF THE RIDGE...CARVING OUT AN INCREASINGLY
DEEP TROUGH OVER THE EASTERN CONUS. THE GFS MAINTAINS A SFC BNDRY
OVER THE REGION ALONG WITH PLENTY OF CAPE THU-SAT. THE ECMWF DIGS
IT/S ENERGY A LITTLE FARTHER WEST AND HAS CONSIDERABLY HIGHER LAYER
RH VALUES ALL THREE DAYS. THE GFS BEING DRIER ALOFT WOULD IMPLY MORE
OF A SEVERE THREAT...ESPECIALLY WITH A BELT OF 30 KT WESTERLIES. THE
ECMWF WOULD SUPPORT HEAVIER PCPN AMOUNTS BUT LESS OF A SEVERE RISK.
BOTH SOLUTIONS WARRANT CARRYING HEALTHY CHANCE POPS ALL THREE DAYS.
MAX TEMPS SHOULD RUN NEAR OR A LITTLE BELOW SEASONABLE LEVELS WHILE
MIN TEMPS WILL RUN A LITTLE ABOVE. THE ECMWF HAS OUR FIRST TASTE OF
COOLER/DRIER AIR OF THE SEASON ON SUNDAY WITH THE FRONT PUSHING TO
THE COAST AND LIFTED INDEX VALUES WELL ABOVE ZERO - A SIGN OF MORE
STABLE AIRMASS. THE LATEST GFS ALSO LOOKS MORE STABLE ON SUNDAY AND
DAY 7 POPS HAVE BEEN REMOVED.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
AT KCLT AND ELSEWHERE...HEALTHY CU FIELD ALONG AND EAST OF I-85 WILL
COMBINE WITH AN NORTHWEST TRACKING BOUNDARY FROM THE EAST OVER THE
NEXT SEVERAL HOURS. IT APPEARS THAT TERMINALS FROM KAND NE TO KCLT
WILL IN THE MOST LIKELY REGION FOR SHRA AND TSRA THROUGH MID
EVENING. I WILL INCLUDE A MENTION OF VCSH OR VCTS THIS AFTERNOON AND
EVENING FOR EACH PIEDMONT TAF. KAVL MAY ALSO SEE A VCSH...BUT LIKELY
LATER IN THE AFTERNOON AND EVENING. FORECAST SOUNDINGS AND MOS
GUIDANCE ARE IN GOOD AGREEMENT OF DEVELOP MVFR CLOUDS AROUND SUNRISE
MONDAY...ESPECIALLY BETWEEN 11Z TO 15Z. KAVL MAY SEE IFR FOG AND
CEILINGS AROUND SUNRISE MONDAY. STALLING COLD FRONT...PLENTIFUL
MOISTURE...AND INSTABILITY WILL FAVOR GREATER SHRA/TSRA COVERAGE MON
AFTERNOON...I WILL MENTION EITHER A PROB30 OR VCTS LATE IN THE TAF
WINDOW.

OUTLOOK...VERY MOIST AIR MASS WILL REMAIN IN PLACE WELL INTO THE
WORK WEEK. EXPECTING SCT/NUM AFTN-EVE TSTMS ACROSS THE AREA EACH
DAY THRU AT LEAST WEDNESDAY. MTN VLYS WILL SEE BEST CHANCE OF
MORNING LOW CLOUDS/FOG.

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...PAT
NEAR TERM...NED/SBK
SHORT TERM...MCAVOY
LONG TERM...MCAVOY
AVIATION...NED

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
409 PM EDT SUN AUG 5 2012

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-062015-
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-
409 PM EDT SUN AUG 5 2012

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

.DAY ONE...TONIGHT.

SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL AFFECT THE
WESTERN CAROLINAS AND NORTHEAST GEORGIA TONIGHT. SOME OF THE
THUNDERSTORMS WILL PRODUCE LOCALLY VERY HEAVY RAIN. CLOUD TO
GROUND LIGHTNING AND BRIEF GUSTY WINDS WILL ACCOMPANY SOME OF THE
STORMS AS WELL.

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

A COLD FRONT WILL STALL ACROSS THE REGION MONDAY THROUGH
WEDNESDAY AS A WEAK TROPICAL LOW ALONG THE GULF COAST LIFTS
ABUNDANT MOISTURE INTO THE REGION. NUMEROUS SHOWERS AND
THUNDERSTORMS WILL DEVELOP ACROSS THE REGION EACH DAY. VERY HEAVY
RAIN WILL ACCOMPANY SOME OF THE SHOWERS AND STORMS...AND A FEW
LOCATIONS MAY SEE ENOUGH RAIN TO CAUSE LOCALIZED FLASH FLOODING.

.SPOTTER INFORMATION STATEMENT...

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

MCAVOY

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
651 PM EDT SUN AUG 5 2012

NCZ036-069>071-052330-
GASTON-IREDELL-LINCOLN-MECKLENBURG-
651 PM EDT SUN AUG 5 2012

...A STRONG THUNDERSTORM WILL AFFECT EASTERN LINCOLN...NORTHEASTERN
GASTON...NORTHERN MECKLENBURG AND SOUTHERN IREDELL COUNTIES THROUGH
730 PM EDT...

AT 645 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR LOWESVILLE...OR 14 MILES EAST OF
LINCOLNTON...MOVING NORTHEAST AT 5 MPH.

* OTHER LOCATIONS AFFECTED INCLUDE BUT ARE NOT LIMITED TO MOUNTAIN
  ISLAND LAKE...LAKE NORMAN...LUCIA...LOWESVILLE...HUNTERSVILLE...
  DAVIDSON AND CORNELIUS.

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

LAT...LON 3530 8101 3544 8114 3555 8100 3555 8097
      3558 8095 3559 8093 3560 8094 3564 8089
      3551 8076 3550 8079 3542 8076

07