Flash Flood in North Carolina, July 14, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
747 PM EDT THU JUL 14 2011

.SYNOPSIS...
A RIDGE OF RELATIVELY COOL HIGH PRESSURE WILL PERSIST ACROSS THE
AREA THROUGH THE WEEKEND BEFORE WEAKENING. A STRONG UPPER LEVEL HIGH
WILL BUILD TO THE WEST NEXT WEEK...ALLOWING TEMPERATURES TO RETURN
TO ABOVE NORMAL ACROSS THE CAROLINAS AND NORTHEAST GEORGIA.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 745 PM EDT...CONTINUED THE TREND OF THE LAST UPDATE WITH
INCREASING AMOUNTS OF CLOUD COVER OVER THE FA. SHRA ARE SLOWLY
APPROACHING FROM THE SOUTH. THE NAM SHOWS A WEAK LLVL WAVE MOVING
ACROSS THE UPSTATE OVER THE NEXT SEVERAL HOURS. THE INCREASED LLVL
WINDS MAY SUPPORT ELEVATED CONVECTION INTO THE SRN PART OF THE
UPSTATE. FOR NOW I STILL HAVE VERY LOW POPS...BUT AN UPWARD REVISION
MAY BE NEED SOON IN THIS AREA. SCATTERED SHRA AND TSTMS WILL ALSO
CONTINUE OVER THE SW NC MTNS FOR SEVERAL MORE HOURS..

PREVIOUS VERSION...
A BACK DOOR COLD FRONT HAS PUSHED WELL SW OF THE CWA THIS AFTERNOON.
NORTH OF THE FRONT...MARGINALLY GUSTY NORTHEAST WINDS WILL RESULT IN
LOWERING OF DEWPOINTS ACROSS THE CWA. MESOSCALE ANALYSIS INDICATES
MINIMAL CAPES ACROSS THE NC PIEDMONT AND FOOTHILLS WITH A NOSE OF
LOWER CAPES EXTENDING SW ALONG I-85 ACROSS THE UPSTATE. ACROSS THE
MTNS AND UPPER SAVANNAH RIVER VALLEY...CAPES RANGED FROM 1000 TO
2000 J/KG. THE INSTABILITY ANALYSIS MATCHES WELL WITH TH LATEST
SATELLITE IMAGES...SHOWING SHALLOW CU ACROSS THE UPPER SAVANNAH
RIVER VALLEY AND NC MTNS WITH MINIMAL CONVECTIVE CLOUDS ACROSS THE
NC FOOTHILLS AND PIEDMONT. BASED ON RADAR TRENDS AND INSTABILITY
ANALYSIS I WILL MAINTAIN CHC POPS ACROSS THE UPPER SAVANNAH RIVER
VALLEY AND NC MTNS...ISO TO NO COVERAGE IS EXPECTED TO THE
NORTHEAST.

THE 12Z SOUNDING FROM KFFC AND KGSO ILLUSTRATE A SIGNIFICANT AIR
MASS CHANGE ACROSS THE FRONT. KFFC...AHEAD OF THE FRONT...OBSERVED
PW AROUND 2.1 INCHES...CAPES AROUND 3500 J/KG...AND A K-INDEX IN THE
U30S. KGSO...NORTH OF THE FRONT...OBSERVED PW AROUND 1.3 INCHES...NO
CAPE...AN LOW K-INDEX. BOTH SOUNDINGS OBSERVED THE WBZ AROUND 14
KFT. IT APPEARS THAT TSRA TODAY WILL REMAIN GARDEN VARIETY...A FEW
STORMS MAY PRODUCE HEAVY RAINFALL...WILL MENTION IN THE HWO.

TONIGHT...IT APPEARS THE SFC PRESSURES WILL INCREASE ACROSS THE CWA
FROM HIGH PRESSURE CENTERED OVER THE MID ATLANTIC. PERSISTENCE
NORTHEAST WINDS SHOULD REINFORCE STABLE AIRMASS ACROSS THE CWA.
LINGERING LLVL MOISTURE AND WEAK UPSLOPE FLOW...I WILL KEEP LCHC TO
SCHC POPS ACROSS THE MTNS. OTHERWISE...CONDITIONS WILL REMAIN DRY
WITH LOW TEMPS AROUND NORMAL. ON FRIDAY...SFC HIGH PRESSURE WILL
BEGIN TO WEAKEN AND SFC WINDS WILL VEER EAST. FORECAST SOUNDINGS
INDICATE A SIGNIFICANT INVERSION AROUND H7 WITH SFC DEWPOINTS IN THE
L60S...YIELDING LITTLE TO NO CAPE. POOLED EAST TN MOISTURE AND WEAK
UPSLOPE FLOW MAY SUPPORT A FEW SHRA/TSRA ACROSS THE MTNS...OTHERWISE
POPS WILL REMAIN LIMITED TO ISO OR LESS EAST OF THE MTNS. A
CONSENSUS OF THE MOS SUPPORTS HIGHS 4 TO 6 DEGREES BELOW NORMAL.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 140 PM THURSDAY...THE OVERALL PATTERN KEEPS THE SE REGION IN A
RELATIVE WEAKNESS OF THE SUBTROP RIDGE THROUGH THE WEEKEND. THIS
WILL ALLOW FOR THE BEST SUBSIDENCE TO THE N AND NW OF THE CWFA...AND
SUBSEQUENTLY AND DEVELOPING AND MAINTAINED SFC HIGH ACROSS THE MID
ATL. WITH THIS PATTERN IN PLACE...WILL EXPECT A MODERATING H92/H85
THETA/E AIRMASS TO MIX INTO THE REGION HELP KEEP MAX TEMPS BELOW
NORMAL BY A FEW DEGREES SAT/SUN. MEANWHILE...THE H85 FLOW WILL TAP
INTO AND ADVECT ENOUGH ATL MOISTURE TO PRODUCE ISOL TO SCT -SHRA
ACROSS THE NC MTNS...EXPECIALLY ACROSS THE BLUE RIDGE. SOUNDINGS
ACROSS THE MTNS INDICATE VIRTUALLY NO SBCAPE OR ELCAPE AS THE MLVLS
REMAIN TOO WARM AND SFC TEMPS REMAIN TOO LOW FOR MUCH THERMAL
LIFT.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 155 PM THURSDAY...THE UPPER PATTERN BEGINS TO CHANGE SUN NIGHT
AS THE WRN RIDGE BUILDS AND SWINGS AN AXIS OVER THE SE REGION MON
THROUGH THE PERIOD. IT MAY TAKE A WHILE TO MODIFY THE LLVL AIRMASS
WITH THE SFC HIGH ANCHORED IN...BUT MAX TEMPS WILL RETURN TO AROUND
NORMAL MON AND EVEN WARMER TUE THROUGH WED. PRECIP CHANCES WILL
REMAIN THE HIGHEST ACROSS THE MTNS...WITH STILL LOW END CHANCE OR
SLIGHT THROUGH THE PERIOD. THERE IS A POSSIBILITY OF A BACKDOOR COLD
FRONT AFFECTING THE AREA AND PERHAPS ENHANCING CONV TUE...HOWEVER
WITH OVERALL STRONG SUBSIDENCE IN PLACE...MOISTURE WILL ONCE AGAIN
BE LIMITED.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AT KCLT...EXPECTING BKN TO OVC CIGS IN THE 4 TO 6 KFT RANGE THROUGH
THE NIGHT. WINDS WILL REMAIN OUT OF THE ENE...THOUGH THEY WILL VARY
AT TIMES BETWEEN ESE AND NE. NO SHRA OR FOG EXPECTED AT THE AIRFIELD
WITH A STABLE AIRMASS OVER THE REGION.

ELSEWHERE...A WEDGE OF SOMEWHAT DRIER AND MORE STABLE AIR WILL
SUPPORT WIDESPREAD CIGS OVERNIGHT. THE CEILING WILL GRADUALLY LOWER
INTO THE MVFR RANGE AFTER MIDNIGHT...EXCEPT AT KHKY...AND THEY MAY
FALL TO IFR FOR A WHILE OVER THE SRN UPSTATE. WINDS WILL GENERALLY
BE OUT OF THE ENE ACROSS THE REGION...EXCEPT LIGHT AND VRBL AT KAVL.
NOT LOOKING FOR MUCH IN THE WAY OF PCPN CHANCES...THOUGH SCT
SHRA/TSTMS MAY DEVELOP OVER THE FRENCH BROAD VALLEY BY TMRW AFTN. IN
FACT...SHRA WON/T BE TOO FAR TO THE WEST OF KAVL MUCH OF THE TAF
PERIOD.

OUTLOOK...DRY AND STABLE HIGH PRESSURE WILL REMAIN RIDGED NE TO SW
ACROSS THE CWA THROUGH THE WEEKEND. MOIST UNSTABLE CONDITIONS SHOULD
REMAIN ALONG THE EDGES OF THE OF THE HIGH...ESPECIALLY ACROSS THE
MTNS. DIURNAL TSRA AND VALLEY FOG MAY DEVELOP ACROSS THE MTNS
THROUGH THE AFTERNOON.

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
249 PM EDT THU JUL 14 2011

GAZ010-017-018-026-028-029-NCZ033-048>053-058-059-062-063-151900-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-MADISON-YANCEY-
MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-NORTHERN JACKSON-MACON-
SOUTHERN JACKSON-
249 PM EDT THU JUL 14 2011

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

ISOLATED TO WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP
OVER THE AREA THIS AFTERNOON. THE MAIN THREATS WILL BE CLOUD TO
GROUND LIGHTNING AND LOCALLY HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

NCZ035>037-056-057-064-065-068>072-082-501>510-SCZ001>014-019-151900-
ALEXANDER-IREDELL-DAVIE-CATAWBA-ROWAN-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-
249 PM EDT THU JUL 14 2011

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.