Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 010513
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
113 AM EDT WED JUL 1 2015

.SYNOPSIS...
AN APPROACHING FRONTAL BOUNDARY AND UNSETTLED AIRMASS WILL SUPPORT
NUMEROUS THUNDERSTORMS THIS AFTERNOON/EVENING...SOME STRONG TO
SEVERE. THIS ACTIVE PATTERN IS EXPECTED TO PERSIST THROUGH THE
WEEKEND...WITH TYPICAL SUMMERTIME AFTERNOON SHOWERS AND
THUNDERSTORMS DEVELOPING EACH DAY AND HIGH TEMPERATURES WARMING TO
ABOVE NORMAL BY EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
0515 UTC UPDATE...POPS AND QPF WERE UPDATED BASED ON RADAR TRENDS.
WINDS WERE UPDATED FROM THE LATEST NAM AND ADJMAV. TEMPERATURES AND
DEW POINTS WERE ADJUSTED SLIGHTLY BASED ON THE LATEST MODEL DATA.

AS OF 920 PM EDT TUESDAY...LET THE CURRENT WW EXPIRE ON SCHEDULE AS
THE ENVIRONMENT IS NO LONGER SUPPORTIVE OF WIDESPREAD SEVERE
CONVECTION.  MADE SOME DOWNWARD ADJUSTMENTS TO POPS TO ACCOUNT FOR
DEPLETION OF COVERAGE OVER THE REGION.  THIS YIELDED ONLY
ISOLATED/SCATTERED SHRA/TSRA FOR THE REMAINDER OF THE
EVENING...TAPERING TO NO POPS BY MORNING WITH POPS LINGERING THE
LONGEST OVER THE NC HIGH TERRAIN.  OTHERWISE...PARTLY CLOUDY SKIES
WILL PREVAIL THIS EVENING WITH THE MOST DENSE SKY COVER ALSO BEING
ACROSS THE MTNS.

PREVIOUS DISCUSSION...

AS OF 245 PM...SEVERE THUNDERSTORM WATCH 373 IN EFFECT FOR THE CWA
UNTIL 9 PM EDT THIS EVENING. A VERY MESSY CONVECTIVE SITUATION IS
UNFOLDING ACROSS THE CWA AT THIS TIME. CLUSTERS OF STRONG TO SEVERE
STORMS WILL PUSH EAST ACROSS THE FOOTHILLS AND PIEDMONT THROUGH
EARLY THIS EVENING. THESE STORMS WILL BE SUPPORTED BY MODERATE
INSTABILITY AND DCAPES BETWEEN 1000 TO 1500 J/KG ACROSS THE UPSTATE
OF SC. FORECAST SOUNDINGS INDICATE THAT CONDITIONS ACROSS THE FA
WILL MAINTAIN BULK SHEAR AROUND 3KTS...FAVORING MULTICELL STORMS.
LATE THIS AFTERNOON INTO THE EVENING...ANOTHER BAND OF STRONG TO
SEVERE STORMS WILL APPROACH THE NC MTNS FROM EASTERN TN. THIS SECOND
BAND IS PRIMARILY SUPPORTED BY AN ADVANCING S/W...NICELY SEEN ON
RECENT W/V IMAGES. THIS LINE OF CONVECTION IS FORECAST TO TRACK SE
ACROSS THE MTNS...LIKELY DISSIPATING EAST OF THE MTNS LATE THIS
EVENING. THE REST OF THE NIGHT...SHRA AND TSRA MAY REMAIN ACROSS THE
TN BORDER COUNTIES...WITH AREAS EAST REMAINING GENERALLY DRY. MIN
TEMPERATURES ARE FORECAST TO RANGE CLOSE TO NORMS.

ON WEDNESDAY...CONDITIONS WILL REMAIN SIMILAR TO TODAY...BUT OVERALL
ALL PARAMETERS ARE FORECAST TO RANGE A LITTLE WEAKER. HIGH
TEMPERATURES ARE FORECAST TO PEAK 3 TO 4 DEGREES COOLER THAN TODAY.
THEREFORE...CAPE VALUES SHOULD PEAK BETWEEN 1000 TO 1500 J/KG. IN
ADDITION...BULK SHEAR IS FORECAST TO FAVOR VALUES WITHIN THE LOW 20
KTS. HOWEVER...SOUNDINGS CONTINUE TO APPEAR WITH AN INVERTED V
ACROSS THE REGION. GFS TIMES A WEAK VORT MAX TO PASS ACROSS THE
REGION DURING THE AFTERNOON. I WILL FORECAST POPS CAT NEAR THE TN
LINE TO SOLID CHC EAST. SPC DAY 2 OUTLOOK HIGHLIGHTS MOST OF THE
AREA UNDER MARGINAL RISK FOR SEVERE STORMS.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...
AS OF 215 PM TUESDAY...AN UPPER TROUGH WILL CONTINUE ACROSS THE
EAST THROUGH THE END OF THE WEEK...BUT EVOLVING INTO SPLIT FLOW
REGIME WITH THE MAIN AXIS OF THE WESTERLIES THROUGH THE GREAT LAKES
AND NEW ENGLAND...WITH A SOUTHERN EXTENSION THEN FROM THE CENTRAL
U.S INTO THE SOUTHERN APPALACHIANS. A NUMBER OF EMBEDDED SHORT WAVES
WILL MOVE THROUGH THE TROUGH AND AFFECT THE AREA. THEREFORE...THE
SENSIBLE WEATHER WILL REMAIN UNSETTLED.

SCT CONVECTION MAY BE ONGOING WED EVENING BUT SHOULD WANE DUE TO
LOSS OF HEATING AND THE PASSAGE TO THE EAST OF A WEAK SHORT WAVE.
HOWEVER...CONVECTION IS EXPECTED TO RAMP UP AGAIN ON THURSDAY
AFTERNOON AS ANOTHER MORE POTENT WAVE APPROACHES AND MOVES THROUGH
THE REGION THU EVENING. WILL RAMP DOWN POPS SOME THU NIGHT BUT SCT
SHRA/TSRA MY CONTINUE OVERNIGHT. FRIDAY SHOULD ALSO SEE NUMEROUS
SHOWERS/THUNDERSTORMS AS YET ANOTHER UPPER WAVE ARRIVES.

IN REGARD TO SEVERE POTENTIAL...SPC HAS THE AREA IN A MARGINAL RISK
FOR THURSDAY AS WIND FIELDS REMAIN STRONGER THAN USUAL FOR THIS TIME
OF YEAR. HOWEVER...FORECAST CAPES ARE ON THE DOWN TREND AS DEEP
LAYER MOISTURE OVERSPREADS THE AREA. LOCALLY HEAVY RAIN MAY BECOME
MORE OF A CONCERN DURING THE LATE WEEK TIME FRAME AS PWATS INCREASE
TO AROUND 2 INCHES. THE FORECAST WILL FEATURE ABOVE CLIMO POPS WITH
MAX TEMPS A LITTLE BELOW CLIMO DUE TO INCREASED CLOUDS COVER AND
PRECIP.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM TUESDAY...THE EXTENDED PERIOD BEGINS FRIDAY NIGHT WITH
THE PERSISTENT LONGWAVE TROUGH OVER THE EASTERN CONUS CONTINUING TO
DEAMPLIFY. A DIFFUSE BOUNDARY WILL HUG THE BASE OF THE TROUGH...AND
OSCILLATE OVER THE SOUTHERN APPALACHIANS OVER MUCH OF THE WEEKEND.
FOR INDEPENDENCE DAY...BOTH GLOBAL MODELS ARE NOW KEYING ON A SMALL
SHORTWAVE RIDGE MOVING OVER THE CWFA DURING THE DAY. THOUGH THERE IS
UNCERTAINTY IN THE AMPLITUDE...PLACEMENT AND TIMING OF THE
FEATURE...IT MAY AFFORD SOME LEVEL OF PROTECTION FOR THE PIEDMONT
AND FOOTHILLS ZONES AND KEEP THE BEST PRECIP COVERAGE OVER THE
HIGHER TERRAIN IN THE AFTERNOON. POPS WOULD THEREFORE BE NEAR CLIMO
FOR OUR EASTERN ZONES...AND JUST ABOVE CLIMO FOR THE WESTERN ZONES.
AT THIS POINT...IT APPEARS THAT A LACK OF ANY IMPRESSIVE INSTABILITY
OR FORCING OVER THE PIEDMONT/FOOTHILLS WILL ALLOW ANY DIURNAL SHOWER
OR THUNDERSTORM ACTIVITY THAT DOES FORM OUTSIDE OF THE MOUNTAINS TO
DISSIPATE SHORTLY AFTER SUNSET. THE BOUNDARY WILL BE IN CLOSER
PROXIMITY TO OUR AREA ON SUNDAY...SO COVERAGE OF DIURNAL SHOWERS AND
STORMS IS EXPECTED TO BE HIGHER THAN SATURDAY. MONDAY AND TUESDAY
WILL BOTH FEATURE SOME BERMUDA HIGH INFLUENCE...AND POPS WILL REMAIN
NEAR CLIMO THROUGH THE BEGINNING OF THE WORK WEEK BEFORE ANOTHER
LONG WAVE TROUGH AND ASSOCIATED FRONTAL BOUNDARY SWEEPS THROUGH BY
THE MIDDLE OF NEXT WEEK.

MAX TEMPS WILL BE ABOUT A CATEGORY ABOVE AVERAGE FOR THE ENTIRE
MEDIUM RANGE...WITH LOWS BEGINNING NEAR AVERAGE AND SLOWLY RISING TO
A CATEGORY ABOVE AVERAGE BY THE END OF THE PERIOD.

&&

.AVIATION /05Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...VFR. MODEL TIME HEIGHTS SUPPORT LOW VFR CLOUDS FOR MUCH OF
THE FORECAST...WITH ENOUGH CLOUD COVER FOR A LOW VFR CIG WEDNESDAY
AFTERNOON AND EVENING IN ASSOCIATION WITH CONVECTION. GUIDANCE DOES
NOT SUPPORT A DAYBREAK FOG RESTRICTION. WINDS WILL FAVOR THE
SW...WITH MODEST DAYTIME GUSTS.

ELSEWHERE...OTHER THAN DAYBREAK MVFR FOG AT KAVL AND KAND...AND AN
OBSERVED IFR CIG AT KGMU WITH POSSIBLE MVFR FOG AT DAYBREAK...VFR
CONDITIONS ARE EXPECTED. GUIDANCE FAVORS A LOW VFR DAYBREAK CIG AT
KAVL THAT BREAKS UP WITH MORNING HEATING...THEN SPREADS LOW VFR CIGS
EAST ACROSS ALL SITES IN THE EARLY AFTERNOON IN ASSOCIATION WITH
CONVECTION. WINDS WILL GENERALLY FAVOR THE WSW...WITH MODEST DAYTIME
GUSTS...EXCEPT AT KAVL WHERE WINDS WILL CHANNEL UP VALLEY FROM THE
NW.

OUTLOOK...A UPPER TROUGH WILL SUPPORT MAINLY AFTERNOON AND EVENING
THUNDERSTORMS THROUGH THE WEEKEND. RESTRICTIONS MAY OCCUR WITH
PASSING STORMS...AND EACH MORNING OVER RAIN SOAKED AREAS.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH  94%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH  83%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

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

&&

$$
SYNOPSIS...JPT
NEAR TERM...CDG/JAT/NED
SHORT TERM...LG
LONG TERM...LEV
AVIATION...JAT


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