Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 221731
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
ISSUED BY NATIONAL WEATHER SERVICE COLUMBIA SC
131 PM EDT WED OCT 22 2014

.SYNOPSIS...
DRY HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 130 PM EDT WEDNESDAY...CURRENT FORECAST REMAINS ON TRACK
THEREFORE NO SIGNIFICANT CHANGES MADE/NEEDED WITH THIS UPDATE.
GUSTY DOWNSLOPE FLOW IS STILL EXPECTED TO PREVAIL THROUGH THE
AFTERNOON BEFORE DECREASING BEYOND SUNSET.  TEMPERATURES HAVE WARMED
RATHER NICELY REGIONWIDE WITH MOST SITES SURGING INTO THE MID TO
UPPER 60S. FULL FORECAST DISCUSSION TO FOLLOW WITHIN THE HOUR.

PREVIOUS DISCUSSION...

AS OF 230 AM...UPSTREAM MOISTURE REMAINS SHALLOW ACROSS THE OH
VALLEY AND ERN TN. DON/T SEE MUCH MORE THAN CLOUDS AFFECTING THE WRN
NC MTNS OVERNIGHT AS NW/LY MLVL FLOW REMAINS RATHER UN/ENERGETIC.
THERE IS STILL A GOOD H85 T/GRAD ATOP THE NC MTNS PROVIDING DOWNWARD
OMEGA AND MODERATE GUSTY CONDS OVER THE HIGHER TERRAIN. THE LLVL
FLOW REMAINS CHANNELED AND A GAP WIND HAS DEVELOPED INTO THE NRN
UPSTATE BRING LOW END GUSTS.

THE SYNOPTIC PATTERN WONT CHANGE MUCH DURING THE DAY...WITH THE ULVL
TROF SLOWLY PULLING NE WHILE A CP HIPRES SYSTEM CONTINUES TO CENTER
OVER THE ERN MIDWEST. WITH THE CP AIRMASS MIX...PWATS WILL DROP TO
ARND 60 PERCENT OF NORMAL OFFSETTING MUCH CLOUD DEVELOPMENT.
HOWEVER...SCT/BKN CU AND STCU WILL CONTINUE ACROSS THE FAR WRN
ZONES. THE AIRMASS MIX WILL ALSO KEEP LLVL THICKNESSES SHALLOW AND
MAX TEMPS WILL BE HELD ABOUT 5 DEGREES BELOW NORMAL NON/MTNS AND
ARND 8-10 DEGREES BELOW NORMAL MTN VALLEYS WHERE H85 CAA REMAINS THE
STRONGEST. THE FAR SRN ZONES SHOULD SEE MAXES NEAR NORMAL IN LESS
AIRMASS MIXING AND GOOD INSOL.

THE UPPER PATTERN REMAINS ALIGNED NW/LY OVERNIGHT WITHIN A TIGHT
HEIGHT FIELD...HOWEVER THE LLVLS WILL SEE A GENERAL BROADENING OF
THE P/GRAD AS HIGH PRESSURE CONTINUES TO RIDGE IN FROM THE NW. THIS
WILL ALLOW WINDS AND THE SFC THERMAL LAYER TO DECOUPLE A LITTLE AND
MINS WILL DROP A COUPLE DEGREES BELOW NORMAL. NO FROST CONCERNS
OVERNIGHT AS LLVL MIXING REMAINS OVER THE NW MTN ZONES...THE SRN MTNS
COULD SEE PATCHY FROST BUT THESE COUNTIES HAVE ALREADY HAD A FREEZE
THIS FALL.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 325 AM WEDNESDAY...TYPICALLY BENIGN MID-AUTUMN WEATHER WILL
PERSIST INTO THE WEEKEND...AS UPPER LOW SPINS OFF THE NORTHEAST
COAST...AND THE MEAN EASTERN LONG WAVE TROUGH IS REINFORCED BY A
SHORT WAVE DIVING OUT OF THE CORN BELT REGION THU NIGHT/FRIDAY.
PERSISTENT NW FLOW SHOULD RESULT IN PERIODS OF STRATOCU ACROSS THE
WESTERN MTNS THROUGH THE PERIOD...BUT MOISTURE IS EXPECTED TO REMAIN
TOO SHALLOW TO SUPPORT UPSLOPE SHOWERS. GOOD RADIATIONAL COOLING
CONDITIONS FRI NIGHT WILL LIKELY RESULT IN AT LEAST PATCHY FROST AND
POCKETS OF FREEZING TEMPS IN THE MTNS. HOWEVER...MTN ZONES FOR WHICH
FROST/FREEZE PRODUCTS ARE STILL BEING ISSUED WILL BE THE LEAST
LIKELY TO GET COLD...AS NW FLOW MAY RESULT IN PERSISTENT UP-VALLEY
WINDS OVERNIGHT...ESP IN THE FRENCH BROAD VALLEY. OTHERWISE...TEMPS
WILL BE NEAR NORMAL THROUGH THE PERIOD.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 330 AM WEDNESDAY...GLOBAL MODEL GUIDANCE CONTINUES TO DEPICT A
PATTERN CHANGE DURING THE MEDIUM RANGE...AS A SERIES OF STRONG SHORT
WAVE TROUGHS INVADE THE WEST COAST. THIS RESULTS IN ESTABLISHMENT OF
A LONG WAVE RIDGE ACROSS THE CENTRAL CONUS...WHICH PROGRESSES TO THE
EASTERN STATES BY THE END OF THE PERIOD. NEVERTHELESS...THIS PATTERN
WILL SUPPORT PERSISTENCE OF GENERALLY DRY HIGH PRESSURE ACROSS OUR
REGION DURING MUCH OF THE PERIOD. CHANCES FOR A FROPA MAY INCREASE
BY THE END OF THE PERIOD...AS THERE ARE SIGNS THE RIDGE MAY BEGIN TO
FLATTEN DURING THIS TIME. TEMPS WILL LIKELY CREEP ABOVE NORMAL BY
DAY 7...AS DEEP BUT DRY SW FLOW GRADUALLY BECOMES ESTABLISHED.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...

AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES
WITH THE POSSIBLE EXCEPTION OF MVFR CIGS AT KAVL.  GUSTY DOWNSLOPE
WINDS WILL HIGHLIGHT THE TAFS THROUGH THE REMAINDER OF THE DAY AS
UPPER TROF AND ASSOCIATED SURFACE CYCLONE EJECT TO THE EAST.
PRESSURE GRADIENT FORCES BETWEEN THESE FEATURES AND INTRUDING
SURFACE RIDGE HAVE COMBINED WITH DEEPENED MIXED LAYER TO PROMOTE
GUSTY NORTHWEST WINDS AT ALL SITES.  GUSTS WILL SUBSIDE AS MIXING
DECREASES AFTER SUNSET WITH SUSTAINED FLOW IN THE 5-8KT RANGE
LIKELY THROUGH THE OVERNIGHT AT ALL SITES.  SKIES WILL REMAIN MOSTLY
SUNNY/CLEAR THROUGH THE REMAINDER OF THE PERIOD ASIDE FOR AT KAVL
WHERE MORNING STRATUS IS POSSIBLE DUE TO INVERSION TRAPPED LOW LEVEL
MOIST UPSLOPE FLOW...WHICH WAS HANDLED WITH A TEMPO.  FLOW WILL
GRADUALLY START TO VEER EAST OF NORTH OVER THE LATER PART OF THE TAF
CYCLE WITH WINDS REMAINING IN THE 6-10KTS RANGE THROUGH 18Z THURSDAY
BENEATH CLEAR SKIES.

OUTLOOK...QUIET WEATHER WILL CONTINUE ACRS THE REGION...AS DEEP
LAYER RIDGING SETTLES IN THRU THIS WEEKEND.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-10Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       MED   65%     HIGH 100%     HIGH 100%     HIGH 100%
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 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...JDL
NEAR TERM...CDG/SBK
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...CDG






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