Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 231602
AFDGSP

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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