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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1202 PM EDT WED JUL 23 2014

.SYNOPSIS...
WEAK HIGH PRESSURE ACROSS THE AREA TODAY WILL MOVE AWAY TONIGHT. A 
SURFACE FRONT WILL APPROACH FROM THE NORTHWEST TONIGHT AND IS 
EXPECTED TO MOVE ACROSS THE CAROLINAS AND NORTH GEORGIA THURSDAY 
AFTERNOON AND EVENING. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT 
FOR FRIDAY AND THE WEEKEND. ANOTHER FRONT IS EXPECTED TO PASS ON 
MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AT NOON EDT...RADAR SHOWS NUMEROUS SHOWERS DEVELOPING OVER THE 
MOUNTAINS...SO THE IDEA OF HIGHER POPS OVER THE TERRAIN IS WORKING 
OUT. THE LATEST HRRR IS SHOWING A BIT MORE CONVECTIVE COVERAGE OVER 
THE FOOTHILLS AND PIEDMONT THIS AFTERNOON WHICH ISN'T SURPRISING 
SINCE CAPES HAVE INCREASED TO 1500-2000J. HOWEVER...COVERAGE SHOULD 
STILL BE SCATTERED IN NATURE. THEREFORE...ADJUSTED POPS PER CURRENT 
TRENDS FOR THE AFTERNOON. ALSO MADE SOME MINOR ADJUSTMENTS TO OTHER 
GRID FIELDS BASED ON CURRENT OBS AND LATEST CONSHORT RUN.   

AS OF 1015 AM...SEE NO REASON BASED ON CURRENT TRENDS AND CAMS TO 
DEVIATE MUCH FROM THE OFFICIAL GRIDS. BASED ON OUR CAMPOP AND TCU 
DEVLOPING PER SAT PICS...I DID BUMP UP THE POPS IN THE NC CENTRAL 
AND SW MOUNTAINS TO SOLID LIKELY THIS AFTERNOON. OTHERWISE...
CONVECTIVE DEVELOPMENT SHOULD BE SCATTERED. TEMPS ARE CURRENTLY 
RISING RAPIDLY SO UPPER 80S STILL LOOKS GOOD FOR MAX TEMPS.

AS OF 6 AM...LATEST 11U-3.9U SATELLITE IMAGES INDICATED AN EXPANDING 
AREA OF LOW CLOUDS ACROSS THE PIEDMONT AND WEST TO THE SOUTHERN NC 
FOOTHILLS. SFC OBSERVATIONS SHOW A WIDE RANGE OF 
VISIBILITIES...RANGING FROM M1/4SM AT KMRN TO 10SM ACROSS THE 
GREENVILLE/SPARTANBURG/ANDERSON AREAS. THE LOWEST VISIBILITIES ARE 
GENERALLY ACROSS THE I-77 CORRIDOR AND WITHIN THE MTN VALLEYS. ALL 
PREFERRED GUIDANCE INDICATES THAT THE FOG WILL DISSIPATE DURING THE 
TWO HOURS FOLLOWING SUNRISE. I WILL UPDATE THE FORECAST TO ADJUST 
FOG AND VISIBILITIES TO THE LATEST OBSERVATIONS AND THINKING. IN 
ADDITION...LATEST MOS HAS TRENDED WARMER FOR THIS AFTERNOON...I WILL 
WARM FORECAST HIGHS A CLICK. OTHERWISE...THE CURRENT FORECAST IS IN 
GOOD SHAPE.

AS OF 320 AM...EARLY MORNING FOG IS EXPECTED TO DEVELOP AND EXPAND 
ACROSS THE I-77 CORRDIOR AND WITHIN THE MTN VALLEYS. THE HRRR 
CONDENSATION PRESSURE DEFICITS INDICATES THAT THE LOWEST VALUES 
WILL EXIST ACROSS THE SOUTHEASTERN HALF OF THE CHARLOTTE METRO AREAS 
AND WITHIN THE MTN VALLEYS. FOG SHOULD DISSIPATE DURING THE FIRST 
TWO HOURS OF SUNLIGHT. IN ADDITION...EARLY MIXING SHOULD YIELD A 
LIGHT SOUTHWEST WIND. GREATER INSOLATION AND SOUTHWEST WINDS SHOULD 
RESULT IN STEADILY WARMING TEMPERATURES FROM SUNRISE TO MID 
AFTERNOON. I WILL FORECAST HIGHS TO RANGE FROM THE L80S WITHIN THE 
MTNS VALLEYS TO U80S TO NEAR 90 EAST OF I-85.

RECENT W/V LOOP INDICATED THAT THE MID LEVEL LOW WAS DRIFTING WEST 
ACROSS THE MISSISSIPPI RIVER DELTA...AS ANOTHER TROUGH WILL DIGGING 
OVER THE OHIO RIVER VALLEY. AT THE SFC...A WEAK LEE TROUGH MAY 
DEVELOP ACROSS THE PIEDMONT DURING THE AFTERNOON. A COLD FRONT WILL 
APPROACH FROM THE NW TODAY...REACHING THE SOUTHERN APPALACHIANS LATE 
TONIGHT. CAMS INDICATE THAT SHRA AND TSRA WILL FAVOR THE MTNS AND 
ADJACENT FOOTHILLS AS EARLY AS MID MORNING TODAY. COVERAGE WILL 
INCREASE THROUGH THE HEAT OF THE AFTERNOON...BECOMING SCT ACROSS THE 
PIEDMONT. CONVECTION SHOULD GENERALLY DISSIPATE EAST OF THE MTNS ONE 
TO TWO HOURS AFTER SUNSET. HOWEVER...I WILL MAINTAIN CHC TO LIKELY 
POPS ACROSS THE TN BORDER COUNTIES TO COVER THE ARRIVAL OF PRE 
FRONTAL CONVECTION. LOW TEMPERATURES TONIGHT ARE FORECAST TO RANGE 
FROM THE MID 60S ACROSS THE MTNS TO LOW 70S EAST.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 230 AM EDT WEDNESDAY...THE MODEL GUIDANCE HAS COME INTO BETTER 
AGREEMENT WITH THE PASSAGE OF A SURFACE FRONT MORE OR LESS DURING 
PEAK HEATING ON THURSDAY. THE FRONT WILL BE DRIVEN ACROSS THE FCST 
AREA BY A FAIRLY STRONG SHORT WAVE IN THE PRESENCE OF SOME UPPER 
DIVERGENCE IN THE ENTRANCE REGION OF THE JET OVER THE NORTHEAST. 
PLENTY OF LOW LEVEL MOISTURE WILL REMAIN AHEAD OF THE FRONT AS WELL. 
THUS...WITH THE TIMING A BIT MORE IN FOCUS...FEEL IT APPROPRIATE TO 
BUMP THE PRECIP PROBABILITY UP INTO THE LIKELY RANGE ACROSS THE 
ENTIRE FCST AREA IN THE AFTERNOON. MIGHT BE A BIT TOO EARLY TO TALK 
TOO MUCH ABOUT SEVERE WEATHER POTENTIAL...BUT THE FRONT SHOULD FOCUS 
STORMS IN AN AIR MASS WITH 1500-2500 J/KG OF CAPE...SO THE DAY2 
OUTLOOK SEEMS APPROPRIATE. SUSPECT WE WILL HAVE TO CONTEND WITH 
SEVERAL SEVERE THUNDERSTORMS. THE FRONT WILL DROP SE DURING THE 
EVENING HOURS ENDING THE PRECIP CHANCE BY THE EARLY MORNING HOURS ON 
FRIDAY. 

BEHIND THE FRONT...THE AIR MASS WILL NOT REALLY BE MUCH COOLER...BUT 
IT SHOULD BE A BIT DRIER ON FRIDAY. HIGH PRESSURE SHOULD MOVE IN 
DURING THE DAY. NOT REALLY SEEING MUCH TO SUPPORT ANY SHOWERS IN THE 
AFTERNOON SO THE PRECIP CHANCES WERE LOWERED. FRIDAY NIGHT SHOULD BE 
DRY AS WELL WITH SEASONAL TEMPS.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 315 AM WEDNESDAY...STILL EXPECTING THE MEAN UPPER TROF OVER 
THE EAST TO FILL OVER THE WEEKEND AS A SHORT WAVE RIDGE MOVES 
THROUGH. THIS WILL SUPPORT WEAK HIGH PRESSURE FOR SATURDAY AND INTO 
SUNDAY. THINK CONVECTION WILL BE LIMITED TO THE RIDGETOPS SATURDAY 
AFTERNOON AND HAVE CUT BACK THE ALREADY MEAGER POP A BIT MORE. 
EARLIER RUNS OF THE MODELS SHOWED THE POTENTIAL FOR UPSTREAM MCS 
DEVELOPMENT ON SATURDAY NIGHT...AND THAT COULD STILL HAPPEN...BUT 
THE MAIN FOCUS LOOKS LIKE IT WILL BE MORE LIKE THE OH VALLEY AND 
CENTRAL APPALACHIANS. SO...SATURDAY NIGHT WAS KEPT DRY ACROSS THE 
MOUNTAINS AS WELL. EXPECT MORE OF A RETURN TO DIURNAL THUNDERSTORMS 
FOR SUNDAY. ANOTHER IN A SERIES OF FAIRLY STRONG SHORT WAVES WILL 
ONCE AGAIN CARVE OUT AN UPPER TROF OVER THE EAST EARLY NEXT WEEK. IT 
STILL LOOKS LIKE THIS WAVE WILL DRIVE ANOTHER COLD FRONT OVER THE 
REGION ON MONDAY. UNLIKE THE EARLIER FRONT...THIS ONE SHOULD USHER 
IN A NOTICEABLY DIFFERENT AIR MASS FOR NEXT TUESDAY AS A COOL 
CONTINENTAL HIGH MOVES DOWN OVER THE NRN PLAINS...THEN MODIFIES AND 
BUILDS IN FROM THE WEST. THAT SHOULD DROP TEMPS A CATEGORY OR MORE 
BELOW NORMAL.

&&

.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...LATEST 11U-3.9U SATELLITE IMAGES INDICATED AN 
EXPANDING AREA OF LOW CLOUDS ACROSS THE PIEDMONT AND WEST TO THE 
SOUTHERN NC FOOTHILLS. SFC OBSERVATIONS SHOW A WIDE RANGE OF 
VISIBILITIES...RANGING FROM M1/4SM AT KAVL/KMRN TO 10SM ACROSS THE 
GREENVILLE/SPARTANBURG/ANDERSON AREAS. THE LOWEST VISIBILITIES ARE 
GENERALLY ACROSS THE I-77 CORRIDOR AND WITHIN THE MTN VALLEYS. ALL 
PREFERRED GUIDANCE INDICATES THAT THE FOG WILL DISSIPATE DURING THE 
TWO HOURS FOLLOWING SUNRISE THIS MORNING. BY 14Z...SW WINDS SHOULD 
DEVELOP WITH VFR CLOUD COVER. SCT PIEDMONT COVERAGE OF LATE 
AFTERNOON TSRA ARE POSSIBLE 18Z TO 24Z. TSRA COVERAGE WILL BE 
SIGNIFICANTLY GREATER ACROSS THE MTNS...HIGHLIGHTED WITH A TEMPO 
18Z-21Z. ANOTHER ROUND OF LIFR FOG/CIGS ARE POSSIBLE ACROSS THE MTNS 
LATE TONIGHT...PATCHY MVFR OVER WET GROUND EAST.

OUTLOOK... SHOWERS AND THUNDERSTORMS THURSDAY WITH THE PASSAGE OF A 
COLD FRONT. SCATTERED SHOWERS AND THUNDERSTORMS MAINLY DURING THE 
AFTERNOONS AND EVENINGS THROUGH THE END OF THE WEEK.

CONFIDENCE TABLE...

            16-22Z        22-04Z        04-10Z        10-16Z 
KCLT       HIGH  99%     HIGH 100%     HIGH 100%     HIGH 100%     
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%     
KAVL       HIGH  92%     HIGH  97%     MED   71%     LOW   50%     
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%     
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%     
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  89%     

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...PM
NEAR TERM...LG
SHORT TERM...PM
LONG TERM...PM
AVIATION...NED

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