Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
205 PM EDT MON JUL 25 2011

.SYNOPSIS...
AN UPPER LEVEL TROUGH WILL PERSIST ALONG THE EAST COAST...WITH A
WEAK COLD FRONT PUSHING SOUTH AND STALLING ACROSS THE AREA TUESDAY.
STRONG RIDGING ALOFT WILL REBUILD OVER THE AREA FROM THE MIDDLE TO
LATE IN THE WEEK.

&&

.NEAR TERM /THROUGH TUESDAY/...
MUCH OF THE RIDGE TOP CONVECTION EARLY THIS AFTERNOON HAS ALREADY
MOVED OUT EAST OF THE BLUE RIDGE. THE COVERAGE OF THESE TSTMS...AND
ADDITIONAL STORMS FROM THE NW...WILL INCREASE THROUGH THE LATE
AFTERNOON HOURS AS UPPER SUPPORT IMPROVES AHEAD OF AN APPROACHING
SHORTWAVE...AND LOW LEVEL CONVERGENCE STRENGTHENS ALONG A LEE
TROUGH. DEWPOINTS IN THE LOWER 70S HAVE PRODUCED SFC BASED CAPE
VALUES AT LEAST 3000 J/KG ACROSS MOST OF THE AREA...HOWEVER....THE
SEVERE TSTM POTENTIAL LOOKS LIMITED GIVEN VERY MOIST
SOUNDINGS...DEEP LAYER SHEAR LESS THAN 15 KT...AND HIGH FREEZING
LEVELS AROUND 15 KFT. HEAVY RAIN MAY BE THE BIGGER CONCERN THROUGH
LATE EVENING. LAPS AND RAOB SOUNDINGS INDICATED PRECIPITABLE WATER
AT OR ABOVE 2 INCHES UP THE COLUMN. LIGHT WESTERLY STEERING FLOW
WILL CREATE A TRAINING HEAVY RAIN THREAT WITH ANY TSTMS THAT FORM.
THE MODELS PLACE THIS THREAT MAINLY ALONG THE INTERSTATE 85 CORRIDOR
TONIGHT...BUT THIS APPEARS TO BE DUE TO CONVECTIVE FEEDBACK. JUST
ABOUT ANY LOCATION WITH REPEATED CELL CROSSINGS WILL HAVE A MARGINAL
HYDRO THREAT GIVEN THE WARM AND WET PROFILES.

A WEAK SURFACE COLD FRONT WILL ARRIVE FROM THE NORTHWEST
OVERNIGHT...WITH DRYING ALOFT DEVELOPING...AND NVA MOVING IN BEHIND
THE SHORTWAVE. FAIRLY GOOD FOG COVERAGE IS EXPECTED OVER THE NW
HALF...AND IN SE LOCATIONS WHERE HEAVY RAIN FALLS...BUT LOW CEILINGS
COULD KEEP IT FROM GETTING TOO DENSE. DEEPER LAYER DRYING WILL THEN
CONTINUE FROM THE NW THROUGH TUESDAY. HOWEVER...LOW LEVELS MAY
REMAIN MOIST AND A CONVERGENCE AXIS WILL LIKELY SET UP ALONG THE ERN
SLOPES OF THE MTNS. THE BETTER PRECIP COVERAGE SHOULD BE CONFINED
MAINLY TO LOCATIONS SOUTHEAST OF INTERSTATE 85...WITH A SECONDARY
MAXIMA POSSIBLE ALONG THE ERN SLOPES OF THE SRN APPALACHIANS. TEMPS
SHOULD RUN INTO THE 80S MTNS TO LOWER 90S PIEDMONT TUE AFTN.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AS OF 130 PM MONDAY...THERE WILL BE RIDGING ALOFT THRU THE SHORT
TERM...AS EAST COAST TROF EXITS TO THE EAST. THIS SETUP WILL PUSH
THE FRONTAL BNDRY FURTHER SOUTH...USHERING IN WEAK DRY NELY LLVL
FLOW. THE NAM AND GFS ARE SUSPECT ON DETAILS WITH RESPECT TO
INSTBY...AS EACH HAVE RESPECTIVE CONVECTIVE FEEDBACK ISSUES WHICH
CORRESPOND TO LLVL WAVES ALONG THE BNDRY TO OUR SOUTH. THESE WAVES
MAY BE FORCING EITHER TOO MUCH OR TOO LITTLE LLVL MOISTURE INTO THE
SOUTHERN HALF OF THE CWFA. SO HAVE NOT MADE ANY MAJOR CHANGES TO
INHERITED RELATIVELY DRY FCST. BASED ON 12Z NAM BUFKIT
SOUNDINGS...MOST OF THE CWFA LOOKS TO BE CAPPED...BUT CONVECTION
OVER THE HIGH TERRAIN WILL LIKELY BE ABLE TO BREAK CAP TO FORM ISOLD
TO WIDELY SCATTERED SHWRS AND PERHAPS AN ISOLD TSTM. CONFIDENCE IN
ABOVE NORMAL TEMPS IS FAIRLY HIGH HOWEVER...WITH 700 MB RIDGE
CENTERED OVER THE SOUTHERN APPALACHIANS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 1145 AM MONDAY...LATEST MODEL GUIDANCE IS IN GOOD AGREEMENT ON
THE UPPER PATTERN ACRS THE REGION...SO I WENT WITH HPC GUIDANCE FOR
THE MEDIUM RANGE.

A SUBTROPICAL RIDGE (AT 500 MB) WILL SLOWLY RETROGRADE AND
STRENGTHEN FROM AN APPROX 594 DAM HIGH EAST OF THE CAROLINA COAST
THURSDAY NIGHT...TO AROUND 598 DAM OVER THE SOUTHERN HIGH PLAINS BY
MONDAY. AS THE SYSTEM RETROGRADES...AN UPPER TROF WILL DIG INTO THE
NORTHEAST STATES...ALLOWING A WEAK COLD FRONT TO SAG SOUTH INTO THE
CAROLINAS BY LATE SUNDAY OR EARLY MONDAY. SO TEMPS WILL RETURN TO
MID-UPR 90S EACH AFTN WITH LOWS MAINLY IN THE UPR 60S MTNS TO
LWR-MID 70S PIEDMONT...WITH TYPICAL AFTN/EVE SCT MTN AND ISOLD
PIEDMONT CONVECTION. WITH THE FRONT APPROACHING THE AREA SUNDAY AND
UPPER TROFINESS LINGERING ON EAST SIDE OF THE RIDGE...A SLIGHTLY
GREATER COVERAGE OF SHWRS/TSTMS IS EXPECTED INTO MONDAY.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AT KCLT...COVERAGE IS FILLING IN ACROSS THE NC FOOTHILLS AND WRN
PIEDMONT THIS AFTERNOON...AND TSRA IS LOOKING INCREASINGLY LIKELY AT
THE AIRFIELD. GIVEN THE HEAVY DOWNPOURS EXPECTED WITH ANY SHOWERS
AND TSTMS IN THE MOIST AIRMASS...CONFIDENCE IS NOW STRONG ENOUGH TO
FEATURE A 2 HOUR TEMPO WINDOW FOR TSRA ALONG WITH BRIEF IFR
CONDITIONS 20Z TO 22Z. WINDS REMAIN TRICKY...WITH FLOW GENERALLY WSW
IN WEAK LEE TROUGHING...BUT PERHAPS TOGGLING WNW WITH OUTFLOWS FROM
CONVECTION TO THE WEST. WINDS SHOULD EVENTUALLY TURN MORE NW WITH
TROUGH/WEAK FRONT PASSAGE LATE TONIGHT...AND GENERALLY N TO NE TUE
MORNING. WILL ADVERTISE MVFR RESTRICTIONS OVERNIGHT...BUT SOME IFR
IS POSSIBLE IF ANY HEAVY RAIN SETS UP OVER THE TERMINAL. WILL HOLD
OFF ON A CB MENTION FOR TOMORROW...BUT PIEDMONT AREAS COULD SEE A
CONTINUED TSTM THREAT INTO TUE WITH LINGERING BL MOISTURE AND
CONVERGENCE.

ELSEWHERE...CONVECTIVE COVERAGE WILL BE ROBUST ACROSS THE
REGION...WITH AT LEAST TEMPO TSRA NOW LIKELY AT ALL LOCATIONS AT
SOME POINT 18Z THROUGH 00Z. GIVEN THE HEAVY DOWNPOURS IN THE MOIST
AIRMASS...IFR RESTRICTIONS SHOULD ACCOMPANY THE THUNDERSTORMS. WSW
WINDS AROUND 10 KT OR LESS THROUGH EARLY EVENING ARE EXPECTED TO
TURN NW TONIGHT AND THEN POSSIBLY N TO NE BEHIND THE WEAK FRONT TUE
MORNING. KAVL AND KHKY COULD SEE IFR CIGS AND VSBY TOWARD DAYBREAK
AS MID LEVEL DRYING WORKS IN ATOP A MOIST BOUNDARY LAYER. THE SC TAF
SITES COULD ALSO SEE IFR RESTRICTIONS OVERNIGHT IF ENOUGH HEAVY RAIN
AFFECTS THE TERMINALS. VFR CIGS SHOULD LINGER THROUGH A GOOD CHUNK
OF THE MORNING HOURS TUE.

OUTLOOK...AN UPPER LEVEL RIDGE WILL BUILD OVER THE TERMINAL FORECAST
AREA THE REST OF THE WEEK. EXPECT MORNING FOG...ESPECIALLY IN THE
MTN VALLEYS...AND ISOLD TO SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS EACH DAY.

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...TJB
NEAR TERM...HG
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...HG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
221 PM EDT MON JUL 25 2011

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-261830-
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-
221 PM EDT MON JUL 25 2011

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

NUMEROUS THUNDERSTORMS WILL AFFECT THE WESTERN CAROLINAS AND
NORTHEAST GEORGIA THROUGH THE EVENING HOURS. ONE OR TWO OF THESE
THUNDERSTORMS COULD PRODUCE DAMAGING WIND GUSTS. THE BIGGER
CONCERN WILL BE THE POTENTIAL FOR LOCALLY HEAVY TO EXCESSIVE
RAINFALL. ISOLATED FLOODING OF LOW LYING AND POOR DRAINAGE AREAS
COULD OCCUR LATE THIS AFTERNOON THROUGH THIS EVENING...ESPECIALLY
IN AREAS REPEATEDLY AFFECTED BY THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

HG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
250 PM EDT MON JUL 25 2011

NCZ037-251915-
DAVIE-
250 PM EDT MON JUL 25 2011

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN DAVIE COUNTY THROUGH
315 PM EDT...

AT 246 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 4 MILES EAST OF SHEFFIELD...OR 6 MILES NORTHWEST
OF MOCKSVILLE...MOVING EAST AT 20 MPH.

THIS STORM WILL BE NEAR...
  FARMINGTON...
  BERMUDA RUN...

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

INTENSE LIGHTNING IS OCCURRING WITH THIS STORM. IF OUTDOORS...STAY
AWAY FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF
POSSIBLE. WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID
USING TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY
ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES.

LAT...LON 3586 8070 3591 8071 3605 8069 3606 8066
      3605 8049 3607 8046 3601 8041 3599 8041
      3596 8037 3593 8037

NED