Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 231109
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
709 AM EDT SAT AUG 23 2014

.SYNOPSIS...
A BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE WILL CONTINUE TO BRING
VERY WARM TEMPERATURES TO MUCH OF THE REGION TODAY. A BACK DOOR COLD
FRONT WILL THEN PUSH INTO THE AREA FROM NORTHEAST USHERING IN COOLER
TEMPERATURES STARTING SUNDAY. TEMPERATURES WILL GRADUALLY RETURN TO
NORMAL THROUGH NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM...FAIRLY QUIET ACROSS THE REGION. A FEW MORE SHOWERS
WERE NOTED OVER NE TN AND THE NRN MTNS OF NC...SO THE CHANCE POP
ALONG THE TN BORDER STILL LOOKS GOOD. THINK THE SHOWERS WILL HAVE A
DIFFICULT TIME MAKING IT PAST THE MOUNTAIN BARRIER FOR THE NEXT FEW
HOURS.

OVER THE NEXT 24 HOURS...THE UPPER PATTERN WILL CONTINUE TO AMPLIFY
WITH THE CENTER OF AN UPPER ANTICYCLONE OVER THE ARKLATEX AND MS
DELTA REGIONS...AND A POSITIVELY TILTED UPPER TROF OFF THE MID
ATLANTIC COAST. A FAIRLY SUBSTANTIAL SHORT WAVE DROPPING DOWN INTO
THE TROF IS EXPECTED TO DRIVE A BACK DOOR COLD FRONT INTO THE AREA
TONIGHT. BEFORE THAT HAPPENS...ONE MORE HOT DAY ACROSS MOST OF THE
REGION WITH PERHAPS THE EXCEPTION OF THE NW PIEDMONT. MORE EXTENSIVE
CLOUDINESS MIGHT KEEP HIGH TEMPS A DEGREE OR TWO BELOW FRIDAYS
HIGHS. THE MODELS SUGGEST THAT THE BALANCE OF THE DAY WILL BE
DRY...PERHAPS FOR LACK OF A TRIGGER BEFORE THE COLD FRONT ARRIVES
FROM THE NE LATE IN THE DAY. AN MVC OR SHORT WAVE DROPS DOWN FROM
THE N BUT SHOULD REMAIN TO THE WEST THIS AFTERNOON. THIS MIGHT
SUPPORT SOME CONVECTION OVER THE MTNS...SO A CHANCE POP WAS KEPT
NEAR THE TN BORDER...BUT NE GEORGIA AND UPSTATE SC WERE KEPT IN THE
SLIGHT CHANCE RANGE UNTIL LATE AFTERNOON WHEN THE POP RAMPS UP TO
CHANCE AHEAD OF THE FRONT. THE TIMING OF THE FRONTAL PASSAGE IS HARD
TO PIN DOWN BECAUSE THE WIND SHIFT MIGHT BE A SUBTLE CHANGE FROM N
TO NE...BUT EXPECT THIS TO MAINLY HAPPEN AFTER SUNSET. A BAND OF LOW
LEVEL MOISTURE CONVERGENCE WILL SUPPORT KEEPING A CHANCE OF PRECIP
ACROSS THE ENTIRE AREA TONIGHT...WITH THE HIGHEST CHANCES NEAR THE
NC BLUE RIDGE AS AN EASTERLY UPSLOPE FLOW DEVELOPS. TEMPS WILL
REMAIN MILD WITH EXTENSIVE CLOUD COVER. CANNOT RULE OUT A FEW SEVERE
STORMS WHICH MAKES SENSE WITH THE EXPECTED AIR MASS CHANGE...BUT THE
POTENTIAL FOR FLASH FLOODING SHOULD ALSO BE HIGHER THAN PREVIOUS
DAYS E OF THE MTNS WITH THE INCREASED LOW LEVEL FORCING AND EASTERLY
UPSLOPE PERHAPS TRAPPING SOME CONVECTION NEAR THE BLUE RIDGE WHILE
WE MAINTAIN HIGH PW.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 245 AM SATURDAY...ON SUNDAY...THE WEDGE FRONT WILL REACH
ACROSS THE DEEP SOUTH BY SUNRISE. RIDGING HIGH PRESSURE WILL REMAIN
ACROSS THE FORECAST AREA ON SUNDAY. THE FORECAST WILL FEATURE
ABUNDANT CLOUD COVER AND STEADY ENE WINDS. POPS WILL REMAIN IN THE
CHC RANGE ACROSS THE MTNS AND NE GA...HIGHLIGHTING LINGERING WEAK
INSTABILITY AND UPSLOPE FLOW. ELSEWHERE...CONDITIONS SHOULD
GENERALLY REMAIN DRY. HIGH TEMPERATURES ARE FORECAST TO RANGE IN THE
70S ACROSS THE HIGH TERRAIN...LOW TO MID 80S ELSEWHERE.

MONDAY...SHORT RANGE MODELS SHOW DEEP DRY AIR ADVECTING SW ACROSS
THE FORECAST AREA. IN ADDITION...THE CENTER OF H5 RIDGE IS EXPECTED
LIFT NORTH ACROSS THE MID MISSISSIPPI RIVER VALLEY...WITH THE
EASTERN EDGE OF THE RIDGE ACROSS THE SOUTHERN APPALACHIANS. GFS
FORECAST SOUNDINGS APPEAR QUITE DRY...PW LESS THAN .75 AND WARM
TEMPERATURES ABOVE H8. SCHC POPS WILL BE LIMITED TO THE WESTERN NC
MTNS...NO MENTIONABLE POPS ACROSS THE REMAINDER OF THE CWA.
TEMPERATURES SHOULD RANGE CLOSELY TO SUNDAY/S VALUES.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 3 AM SATURDAY...TUESDAY AND WEDNESDAY...SFC RIDGING WILL
CONTINUE ACROSS THE CWA...BUT TRENDING WEAKER WITH LIGHTER WINDS.
THE CENTER OF H5 590DM RIDGE WILL LIKELY SHIFT ACROSS THE SOUTHEAST.
TEMPERATURES SHOULD WARM TO NEAR NORMAL BY WEDNESDAY...AIDED BY
WARMING LLVL THICKNESSES AND INSOLATION. FORECAST SOUNDINGS INDICATE
THAT CONDITIONS WILL REMAIN DRY AND STABLE...SUPPORTING SINGLE DIGIT
POPS. THURSDAY AND FRIDAY...TROPICAL LOW IS EXPECTED TO TRACK OFF
THE CAROLINA COAST. THE GFS INDICATES THAT A COLD FRONT WILL SWEEP
ACROSS THE REGION ON FRIDAY...ACCOMPANIED BY A LONGWAVE TROF. THE
ECMWF KEEPS THE REGION UNDER MID LEVEL RIDGING AND SFC HIGH
PRESSURE...KEEPING ANY SFC BOUNDARIES WELL NORTH OF THE REGION.
NATIONAL GUIDANCE FAVORS THE ECMWF SOLUTION. I WILL INDICATE
SEASONABLE TEMPS WITH DIURNAL CHC POPS.

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...EXPECT CONDITIONS TO REMAIN VFR THROUGH TODAY AND THIS
EVENING. STILL MIGHT BE SOME BRIEF MVFR FOG AROUND METRO CLT FOR THE
FIRST HOUR...BUT NOT AT THE AIR FIELD. THINK FOR THE MOST PART THE
DAY WILL BE SIMILAR TO FRIDAY...WITH CONVECTION NOT DEVELOPING UNTIL
THE LATE AFTERNOON AND EVENING AS A BACK DOOR COLD FRONT APPROACHES.
HANDLED THIS WITH A PROB30 TO ENCOMPASS A LARGER TIME PERIOD. THIS
WILL BE CHANGED TO A TEMPO FOR TSRA WHEN TIMING OF STORMS WITH THE
FRONTAL PASSAGE BECOMES CLEARER. BEHIND THE FRONT...AN EASTERLY
COMPONENT DEVELOPS AT LOW LEVELS...WHICH SHOULD BRING THE CEILING
DOWN INTO THE MVFR RANGE...STARTING AROUND 08Z. THERE COULD EASILY
BE SOME IFR CEILING DEVELOPING BEFORE DAYBREAK...BUT THIS WILL BE
LEFT OUT FOR NOW FOR BREVITY.

ELSEWHERE...SIMILAR TO KCLT. EXPECT WEAKENING MCS REMNANTS TO AFFECT
THE MTNS ALONG THE TN BORDER AND THE NRN FOOTHILLS EARLY THIS
MORNING. THIS COULD IMPACT KAVL AND KHKY...SO A VCSH WAS USED AND
AMENDMENTS WILL BE MADE IF SHOWERS SURVIVE INTO THE MTNS.
OTHERWISE...VFR EXPECTED THRU THE DAYTIME PERIOD. WINDS SHOULD BE
LIGHT N...AND THEN BECOMING MORE NE LATE IN THE DAY. ANOTHER
ROUND OF SCT CONVECTION POSSIBLE LATER IN THE DAY BUT THIS WAS
PUSHED OFF UNTIL LATE AFTERNOON AND EVENING BASED ON THE NAM. THE
BACK DOOR COLD FRONT WILL PUSH SW ACROSS THE REGION THROUGH THE
EVENING.

OUTLOOK...A MORE DIURNAL PATTERN OF EARLY MORNING LOW CLOUDS/FOG AND
ISOLD AFTN TSTMS MAY RETURN EARLY NEXT WEEK...WITH STEADY DRYING.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-11Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  97%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  91%
KAVL       HIGH  97%     HIGH 100%     HIGH 100%     MED   73%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  84%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  95%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  95%

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





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