Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 200545
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
145 AM EDT MON OCT 20 2014

.SYNOPSIS...
DRY AND COOL CANADIAN HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS
THE REGION THROUGH MONDAY. A WEAK COLD FRONT WILL CROSS THE AREA
TUESDAY...BRINGING WITH IT SMALL CHANCES OF RAIN. DRY AND MOSTLY
SUNNY WEATHER WILL PREVAIL THE REST OF THE WEEK WITH TEMPERATURES
TYPICAL FOR THE SEASON.

&&

.NEAR TERM /THROUGH TODAY/...
130 AM EDT UPDATE...NO MAJOR CHANGES NEED TO THE GOING FCST FOR THE
NEXT FEW HRS. MADE SOME SIGFNT SKY COVER INCREASES ACROSS THE MTNS
WITH CI PATCH DEFINED IN S/W FLOW. RELIED ON MADIS SFC OBS FOR
MANUAL HR/LY T/TD GRID EDITS...WHICH RESULTED IN A BUMP UP ACROSS
THE HIGHER TERRAIN AND DOWN A BIT NON/MTNS. MIN TEMPS AND TD/S WILL
BE MARGINAL ACROSS THE NRN MTN VALLEYS FOR AREAS OF FR
FORMATION...BUT SOME PATCHY FR IS PROBABLE BEFORE DAYBREAK.

AS OF 1030 PM...THE MAIN CHANGES TO THE FCST WITH THIS UPDATE WERE
TO INCREASE THE DEWPTS ACRS THE CWFA...MOST AREAS BY 4-8F. THIS
TREND IN ADDITION TO BUMPING UP SKY COVER FOR THE GENERALLY THIN
CIRRUS...INCREASES MY CONFIDENCE THAT MOST OF THE AREA WILL NOT HAVE
MUCH FROST POTENTIAL. I DID OPT TO LEAVE MIN TEMPS ALONE...BUT THEY
MAY BE TOO COLD IN SPOTS. THE ONE EXCEPTION TO THIS IS THE NORTHERN
NC MTNS...WHERE SOME OF THE VALLEYS HAVE SEEN A SHARP DROP IN TEMPS
ALREADY INTO THE UPPER 30S IN SPOTS. I BEEFED UP THE AREA OF PATCHY
FROST IN THE GRIDS FOR THE NORTHERN THREE COUNTIES. GIVEN THE HIGH
CLOUDS...DEWPTS IN THE UPPER 30S TO MID 40S...AND A LIGHT...BUT
INCREASING SWLY LLVL FLOW...I OPTED NOT TO ISSUE AN ADVISORY...AS I
DON/T THINK A WIDESPREAD KILLING FROST WILL OCCUR.

OTHERWISE...WITH LIGHT WINDS AND JUST PERIODS OF THIN CIRRUS...TEMPS
WILL DIP INTO THE UPPER 30S TO MID 40S WHICH IS ABOUT 5-10 DEGREES
BELOW NORMAL.

HIGH PRESSURE WILL DRIFT OFF THE EAST COAST ON MONDAY AS THE NEXT
UPPER SHORT WAVE DROPS DOWN THROUGH THE MIDWEST TO THE TN VALLEY BY
THE END OF THE DAY. MOISTURE WILL INCREASE FROM THE NW AHEAD OF THE
MID/UPPER FORCING LATE IN THE DAY...THAT COULD RESULT IN A FEW
SHOWERS MAINLY ALONG THE TN BORDER OF THE NC MTNS. WILL INCLUDE A
SLIGHT CHANCE POP AFTER 21Z. TEMPS WILL REBOUND A FEW DEGREES WITH
WEAK WARM ADVECTION DEVELOPING.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
AS OF 200 PM EDT SUNDAY...AN UPPER TROUGH CONTINUES TO DIG INTO THE
SOUTHEAST WITH ITS AXIS CROSSING THE FORECAST AREA MON NIGHT INTO
EARLY TUE. THIS OPEN TROUGH IS PROGGED TO CLOSE OFF AS AN UPPER LOW
JUST TO OUR NORTHEAST BY TUE NIGHT AND SLOWLY MOVES OFF THE MID
ATLANTIC COAST THROUGH WED WEDNESDAY...LEAVING OUR CWA UNDER N/NNW
FLOW ALOFT DURING THIS PERIOD.

AT THE SURFACE...A SURFACE LOW OVER THE EASTERN GREAT LAKES REGION
MON NIGHT WILL MOVE EASTWARD INTO THE NE COAST BY TUE NIGHT. THIS
WILL PUSH AN ASSOCIATED WEAK COLD FRONT THROUGH THE FORECAST AREA
DURING THE DAY ON TUESDAY WITH SW WINDS VEERING TO THE NW IN ITS
WAKE. MODEL CROSS SECTION SHOWS NEARLY SATURATED MOISTURE LAYER
DEVELOPING UP TO 800MB ALONG THE TN BORDER AS LLVL MOISTURE WRAPPING
AROUND THE LOW REACHES THE SOUTHERN APPALACHIANS IN PREVAILING NW
FLOW. WITH THE COMBINATION OF UPSLOPE NW FLOW AND LLVL
MOISTURE...MODELS SHOW LIGHT QPF RESPONSE ALONG THE TN BORDER LINE.
THEREFORE...HAVE CARRIED SLIGHT CHANCE TO LOW END CHANCE FOR LIGHT
SHOWERS MAINLY OVER THE NORTHERN NC MTNS TUE INTO EARLY WED. COOL
AND DRY CANADIAN HIGH PRESSURE WILL BUILD IN FROM THE NW BEHIND THE
FRONT...YIELDING DRY CONDITIONS FOR MOST LOCATIONS ON WED.
TEMPERATURES WILL BE NEAR NORMAL ON TUE AND DROP BY 8-10 DEGREES ON
WED. MIN TEMPS DURING THE SHORT RANGE PERIOD APPEARS TOO WARM FOR
FORST CONCERNS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 100 PM EDT SUNDAY...AN UPPER LEVEL LOW SPINNING OFF THE
MID-ATLANTIC COAST WED NIGHT WILL LIFT OFF TOWARD THE NE WHILE AN
UPPER SHORTWAVE DIGS INTO THE REGION BY LATE FRI...OFF THE SE COAST
BY SAT. HEIGHTS WILL THEN RISE OVER THE FORECAST AREA SAT INTO SUN
AS AN UPPER RIDGE BUILDS IN FROM THE CENTRAL CONUS.

AT THE SURFACE...DRY AND COOL CANADIAN HIGH PRESSURE WILL CONTINUE
TO BUILD IN FROM THE NW WED NIGHT INTO FRI AND BECOMES CENTERED OVER
THE REGION SAT INTO SUN. THIS WILL RESULT IN A PROLONGED PERIOD OF
DRY WEATHER THROUGHOUT THE MEDIUM RANGE PERIOD. TEMPERATURES WILL
START OUT AROUND 5-10 DEGREES BELOW NORMAL ON THU...AND A GRADUAL
WARMING TREND IS EXPECTED FRI THRU SUN.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AT KCLT AND ELSEWHERE...VFR FLIGHT CONDS THROUGHOUT THE TAF PERIOD.
SFC HIPRES CONTINUES TO CENTER ACROSS THE CAROLINAS THIS MORNING
MAKING FOR CALM WINDS. SHALLOW MIXING IN WEAK FLOW WILL BE HAD
THROUGH THE AFTERNOON...WITH LIGHT SFC WIND DIRECTIONS BECOMING
DEFINED SSW/LY INTO THE AFTERNOON AS THE HIGH CENTER SHIFTS EAST. A
LATE AFTERNOON SHIFT TO W/LY IS POSSIBLE WITH CROSSING ULVL TROF
AXIS...BUT AGAIN WINDS WILL REMAIN LOW END.

OUTLOOK...DRY HIGH PRES WILL GENERALLY DOMINATE THROUGH TUESDAY.
ANOTHER ROUND OF GUSTY NW WINDS AND MOUNTAIN STRATOCU WILL BE
POSSIBLE BEHIND ANOTHER (MOSTLY DRY) COLD FRONT LATE TUE INTO EARLY
WED. OTHERWISE...VFR CONDITIONS SHOULD PREDOMINATE INTO LATE WEEK.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-05Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     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...JOH
NEAR TERM...ARK/SBK
SHORT TERM...JOH
LONG TERM...JOH
AVIATION...SBK






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