Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 092352
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
752 PM EDT WED JUL 9 2014

.SYNOPSIS...
A FRONTAL BOUNDARY WILL PUSH THROUGH THE AREA TONIGHT AND REMAINS IN
PLACE THURSDAY BEFORE WASHING OUT BY FRIDAY. WEAK HIGH PRESSURE WILL
RETURN THROUGH THE WEEKEND BEFORE ANOTHER COLD FRONT APPROACHES THE
AREA EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 745 PM...WIDELY SCATTERED SHRA/TSRA REMAINED ACROSS THE
FORECAST AREA. I WILL UPDATE THE FORECAST TO LOWER POPS ACROSS THE
I-77 CORRIDOR...KEEP CHC POPS ELSEWHERE. I WILL ALSO INCREASE THE
MENTION OF FOG ACROSS THE REGION LATE TONIGHT.

AS OF 530 PM...A LARGE CLUSTER OF THUNDERSTORMS WAS PUSHING ACROSS
THE I-77 CORRDIOR. I WILL UPDATE THE FORECAST TO INCREASE POPS OVER
THE NEXT TWO HOURS ACROSS THE CLT METRO AREA. OUTFLOW GOVERNED
TEMPERATURES WILL REMAIN CHALLENGING THROUGH THE EVENING...I WILL
UPDATE WITH OBS.

AT 215PM...MOST THUNDERSTORM COVERAGE AT MID AFTERNOON IS ACROSS THE
SOUTHERN UPSTATE EASTWARD INTO NC. NUMEROUS STORMS DEVELOPED IN A
DIFFERENTIAL HEATING AXIS CREATED BY CLOUD COVER TO NORTH EARLIER
TODAY. PLUS THE LEE TROF HAS PROVIDED SOME LOW LEVEL CONVERGENCE. AN
UPPER SHORT WAVE DEPICTED BY THE RAP IS ALSO CROSSING THE AREA.
SHOULD SEE SOME ADDITIONAL DEVELOPMENT ACROSS THE NC
MOUNTAINS/FOOTHILLS PER CAMS SO WILL CONTINUE WITH SCT TYPE POPS
THOSE AREAS. SHOULD SEE THE COVERAGE OF CONVECTION WANE THIS EVENING
AS S/W MOVES TO THE E. HOWEVER...A COLD FRONT JUST WEST OF THE
APPALACHIANS IS FORECAST TO MOVE INTO THE NC MOUNTAINS THIS EVENING
WHICH COULD KICK OFF SOME ADDITIONAL SHOWERS/THUNDERSTORMS...SO WILL
SHOW AN UPTICK IN POPS OVER THE WEST THIS EVENING AGAIN. THE 12Z GFS
SEEMS TO HAVE SOME CONVECTIVE FEEDBACK OVER FAR WESTERN NC IN THE
00Z-06Z TIMEFRAME AND WILL NOT BUY INTO THE HIGH GFS QPF DEPICTED
THERE.

ON THU...THE FRONT IS FORECAST TO REACH THE PIEDMONT. THE MODELS
DEPICT A WEAK WAVE DEVELOPING ON THE BOUNDARY WHICH SHOULD TEND TO
ENHANCE THE COVERAGE NEAR IT. PLUS...ANOTHER WEAK SHORT WAVE IS
FORECAST TO CROSS THE AREA. HENCE...WILL STAY WITH THE IDEA OF
SCT-NUMEROUS SHOWERS/STORMS ACROSS THE PIEDMONT DURING THE
AFTERNOON...WITH LOWER POPS TO THE NORTH. SOUNDINGS LOOK MORE
SATURATED WITH LESS DCAPE...SO DO NOT EXPECT MUCH IN THE WAY OF A
SEVERE THREAT. MAX TEMPS ARE FORECAST TO BE ABOUT A CATEGORY BELOW
CLIMO.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 100 PM WEDNESDAY...THE SHORT TERM PERIOD INITIALIZES THURSDAY
EVENING WITH A QUASI STATIONARY FRONTAL BOUNDARY POSITIONED JUST
SOUTH OF INTERSTATE 85 INTO THE MIDLANDS OF SC...STRETCHING
NORTHEASTWARD INTO CENTRAL NC.  SCATTERED CONVECTION WILL LIKELY BE
ONGOING AS HEATING WILL HAVE STEEPENED LAPSE RATES IN PROXIMITY TO
THE SURFACE BOUNDARY...WHICH WILL PROVIDE A FOCUS FOR SAID
CONVECTION.  MEANWHILE...POSITIVELY TILTED UPPER TROF WILL BE
LIFTING TO THE NORTHEAST ALLOWING H5 HEIGHTS TO RISE.   POPS WILL
TAPER DOWN DUE TO RISING HEIGHTS ALOFT AND HEATING LOSS INTO THE
OVERNIGHT HOURS OF FRIDAY MORNING.  LATEST GUIDANCE INDICATES
POTENTIAL WEAK MESOLOW DEVELOPMENT ALONG THE FL PANHANDLE ON FRIDAY
MORNING ALLOWING FOR ENHANCED SOUTHEASTERLY FLOW INTO THE
CAROLINAS.  THIS COMBINED WITH FLOW AROUND THE WESTERN ATLANTIC
SURFACE RIDGE WILL ALLOW THE STALLED FRONTAL BOUNDARY TO GRADUALLY
LIFT NORTHWARD TOWARDS THE CWFA INTO THE LATE AFTERNOON HOURS.
MOISTURE CONVERGENCE ALONG THIS BOUNDARY WILL PROVIDE A FOCUS FOR
CONVECTION ACROSS THE NC/SC PIEDMONT WHERE STEEPENING LAPSE RATES
AND INCREASED MOISTURE YIELD SBCAPE VALUES IN EXCESS OF 1500J/KG.
THUS WILL FAVOR LOW END CHANCE LEVEL POPS ACROSS THE PIEDMONT...AND
ALSO ALONG THE HIGH TERRAIN WHERE EAST SOUTHEAST UPSLOPE FLOW AIDS
CONVECTION.  SLIGHT CHANCE POPS WILL OVERSPREAD THE REMAINDER OF THE
FORECAST AREA BEFORE DIURNAL COOLING WARRANTS TAPERED POPS ACROSS
THE ENTIRE REGION FOR THE OVERNIGHT.

SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS THE NORTHEAST
INTO THE WEEKEND...AND WILL EXTEND SOUTHWARD INTO THE
SOUTHERN/CENTRAL APPS.   THIS COMBINED WITH RISING HEIGHTS ALOFT
WILL LIMIT CONVECTION EARLY ON SATURDAY BEFORE WEAK CIN IS OVERCOME
BY HEATING.  EXPECTING INITIATION TO OCCUR ACROSS THE HIGH TERRAIN
ON SATURDAY AFTERNOON BEFORE WEAK NW FLOW ALOFT PROPAGATES SHOWERS
AND THUNDERSTORMS SOUTHEAST INTO THE FOOTHILLS/PIEDMONT REGIONS OF
NC/SC.  DIURNALLY FAVORED LOW/MID LEVEL CHANCE POPS WILL HIGHLIGHT
THE FORECAST FOR SATURDAY.  TEMPERATURES THROUGH THE SHORT TERM
PERIOD WILL BE AT OR JUST SLIGHTLY BELOW CLIMO.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 245 PM EDT TUE...THE LATEST GLOBAL MODELS CONTINUE TO INDICATE
THAT UPPER H5 HEIGHTS WILL FALL ACROSS THE SOUTHEAST SAT NIGHT INTO
SUN AS AN UPPER RIDGE OF HIGH AMPLIFIES OVER THE WESTERN CONUS WHILE
AN UPPER LOW PRESSURE TROUGH APPROACHES THE GREAT LAKES REGION FROM
SOUTH CENTRAL CANADA. THIS TROUGH IS EXPECTED TO SWING ACROSS THE
EASTERN STATES MON THROUGH WED.

AT THE SURFACE...BERMUDA HIGH WILL PERSIST THROUGH SUN BEFORE
SHIFTING TO THE EAST BY EARLY MON AS A COLD FRONT APPROACHES FROM
THE NW. THE FRONT IS EXPECTED TO CROSS THE AREA THROUGH MON NIGHT
FOLLOWED BY ANOTHER FRONT ON TUE. THE FRONT WILL REMAIN SOUTH OF THE
AREA WED AS A CONTINENTAL HIGH BUILDS IN FROM THE NW. AS FOR OUR
SENSIBLE WEATHER...POPS REMAIN NEAR CLIMO EACH DAY GIVEN LITTLE TO
NO CAPPING ALOFT AND SEASONABLY UNSTABLE AIRMASS DURING THE PEAK
HEATING HOURS. TEMPERATES WILL REMAIN NEAR...OR A FEW DEGREES BELOW
NORMAL THROUGH THE PERIOD.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AT CLT...THE TERMINAL RECEIVED 0.15 INCHES THIS AFTERNOON...ENOUGH
TO WET THE SOIL. THE CONCERN OVER THE WET GROUND IS THE POTENTIAL
FORMATION OF FOG LATE TONIGHT. A COLD FRONT WILL SLOWLY APPROACH
FROM THE NW TONIGHT...LEAVING CLT IN A PREFRONTAL ENVIRONMENT. THESE
SITUATIONS COMMONLY RESULT IN AT LEAST A PERIOD OF MVFR FOG...I WILL
TEMPO BETWEEN 11Z TO 13Z. WINDS WILL REMAIN LIGHT AND FROM VARYING
DIRECTIONS...RESULTING FROM A LEE TROF AND WEAK FRONT. BASED ON
CAMS...I WILL USE A PROB30 FOR TSRA BETWEEN 17Z TO 23Z.

ELSEWHERE...AFTERNOON CONVECTION HAS EITHER DIRECTLY IMPACTED OR
OCCURRING IN THE VICINITY OF ALL THE TERMINALS. BASED ON THE POSITION
OF THE FRONT AND WET GROUND I WILL MENTION MVFR FOG AT ALL
SITES...KAVL DOWN TO IFR. BY EARLY THURSDAY AFTERNOON...CONDITIONS
WILL DESTABILIZE WITHIN A SFC TROF. I WILL HIGHLIGHT THE CONVECTION
POTENTIAL WITH A LATE AFTERNOON PROB30 FOR ALL SITES.

OUTLOOK...SCATTERED MAINLY AFTN THUNDERSTORMS WILL CONTINUE THROUGH
LATE WEEK INTO THE WEEKEND AS HIGH PRESSURE SLOWLY SETTLES OVER THE
AREA. ANY RESTRICTIONS WOULD BE CONFINED TO DIURNAL TSTMS AND
MORNING VALLEY FOG EACH DAY.

CONFIDENCE TABLE...

            00-06Z        06-12Z        12-18Z        18-24Z
KCLT       HIGH 100%     HIGH  95%     HIGH  95%     HIGH  90%
KGSP       HIGH 100%     HIGH  91%     HIGH 100%     MED   73%
KAVL       HIGH  95%     HIGH  86%     HIGH  82%     HIGH  80%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     MED   61%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  93%
KAND       HIGH 100%     HIGH  91%     HIGH 100%     HIGH  93%

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...JOH
NEAR TERM...LG/NED
SHORT TERM...CDG
LONG TERM...JOH/WIMBERLEY
AVIATION...NED





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