Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 210543
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
143 AM EDT TUE OCT 21 2014

.SYNOPSIS...
A WEAK COLD FRONT WILL CROSS THE REGION FROM THE NORTHWEST TODAY
FOLLOWED BY DRY NORTHWEST FLOW ON WEDNESDAY. DRY HIGH PRESSURE WILL
THEN RETURN ON THURSDAY AND LINGER INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TODAY/...
130 AM EDT UPDATE...NO SIGFNT CHANGES NEEDED TO THE GRIDS. MID LEVEL
CLOUDS AND -DZ/SPRINKLES ARE MOVING EAST OF THE CWFA. MADE SOME
TWEAKS TO SKY GRIDS EAST AND ALSO WEST WHERE STCU COVERAGE UPSTREAM
IS LESS THAN ADVERTISED BY PREVIOUS GUIDANCE AND FCSTS. TEMP/TD
CURVES LOOK GOOD.

AS OF 915 PM...ANOTHER QUICK UPDATE TO ADD MENTION OF SHWRS ACRS
MUCH OF THE NC PIEDMONT. BASED ON THE LATEST OBS...SEVERAL RAIN
GAGES HAVE REPORTED UP TO 0.05" OF RAIN. THE SHOWERS SEEM TO BE
LOSING INTENSITY AND COVERAGE NOW AS THEY CROSS THE NC PIEDMONT. IN
ANY CASE...SHWRS AND CLOUDS WILL BEGIN TO CLEAR OUT LATE EVENING
THRU THE OVERNIGHT. IT WILL BE INTERESTING TO SEE IF THIS LITTLE BIT
OF RAIN WILL INCREASE FOG POTENTIAL...ESP IN THE NC MTNS. I DID NOT
CHANGE THE FOG/VSBY IN THE GRIDS WITH THIS UPDATE.

AS OF 730 PM...THE MAIN BAND OF MID-UPR LVL MOISTURE IS CURRENTLY
CROSSING THE MTNS...WITH A FEW SPOTTY RETURNS ON RADAR. BOTH KAVL
AND K1A5 REPORTED LIGHT RAIN...BUT LITTLE IF ANY AREAS WILL RECEIVE
MEASURABLE AMTS. I DID TWEAK POPS TO FOLLOW A SLGT CHC AREA WITH THE
MOISTURE BAND INTO THE NC FOOTHILLS. OTHERWISE...JUST AN INCREASE IN
CLOUDS WITH SEASONABLE TEMPS THIS EVENING.

AS OF 500 PM...ONLY A FEW MINOR TWEAKS TO T/TD AND SKY GRIDS HEADING
INTO THE EARLY EVENING HOURS. OTHERWISE...FCST LOOKS ON TRACK.

AS OF 245 PM EDT...WATER VAPOR IMAGERY SHOWS UPPER LOW SPINNING
ACROSS LOWER MICHIGAN...WITH THE FIRST S/W BEING PUSHED INTO EASTERN
KY. THE FIRST WAVE IS ACCOMPANIED BY A BAND OF CIGS CONSISTING OF
MID LEVEL CLOUDS. THE MODEL PLANE SECTION RH DATA...POINT RH DATA
AND BUFKIT INFORMATION ALL SHOW THIS SLUG OF MOISTURE CROSSING OUR
FORECAST AREA TONIGHT. THE MODELS INSIST THAT OUR NRN MOUNTAINS
COULD STILL SQUEEZE OUT A FEW SPRINKLES...AND WE WILL FOLLOW THAT
COURSE.

MEANWHILE ONCE THAT FIRST BAND OF CLOUDS PASS...AND BEFORE THE NEXT
SURFACE FRONT MAKES IT INTO OUR REGION...THERE APPEARS TO BE A
WINDOW OF OPPORTUNITY WITH LIGHT WINDS AND POTENTIAL FOG DEVELOPMENT
FOR A FEW HOURS LATE TONIGHT/VERY EARLY TUESDAY MORNING...IN PARTS
OF THE CENTRAL AND SRN NC RIVER VALLEYS...NE GA AND THE NW PORTIONS
OF UPSTATE SC. WE WILL ADD FOG TO THIS FORECAST. TEMPERATURES SHOULD
BE ABOVE READINGS OF LAST NIGHT WITH THE PERIOD OF CLOUDS MOVING
THROUGH.

THE COLD FRONT WILL CROSS OUR REGION TUESDAY MORNING. NICE
PERPENDICULAR LOOK OF THE H85 HEIGHT CONTOURS...RELATIVE TO THE H85
THERMAL PATTERN...SUGGESTS VERY GOOD CROSS CONTOURING...YIELDING
GUSTY WINDS. UPSLOPE FLOW...ALONG WITH A STRONG 2DRY S/W TUESDAY
AFTERNOON...WILL HELP WITH THE GENERATION OF SCATTERED SHOWERS.

THE MODELS ARE NOT TOO KEEN ON COLD AIR CU ELSEWHERE...BUT WOULD BE
SURPRISED IF THEY WERE ABSENT. WE HAVE FOLLOWED AN AVERAGE
TEMPERATURE FORECAST BASED ON OUR MOST RELIABLE MODEL GUIDE SET.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
AS OF 205 PM EDT MONDAY...A STRONG UPPER LOW WILL MOVE OFF THE
MID-ATLANTIC COAST TUESDAY NIGHT. A SHORT WAVE RIDGE IS FORECAST TO
BUILD OVER THE SE STATES IN ITS WAKE WED INTO THU. DEEP LAYER N/NW
FLOW WILL PERSIST THROUGH WED ALONG WITH ASSOCIATED COLD ADVECTION.
THICKNESSES WILL REBOUND SOME ON THU AS UPPER HEIGHTS INCREASE. DRY
WEATHER IS EXPECTED THROUGH THU AS THE LOW TO THE NE PULLS AWAY AND
SURFACE HIGH PRESSURE TO THE NW SLOWLY BUILDS TOWARD THE AREA. THE
EXCEPTION TO THE TOTALLY DRY FORECAST MAY BE A FEW SPRINKLES IN THE
NORTHERN MOUNTAINS TUE NIGHT DUE TO UPSLOPE NWLY FLOW. MODEL TIME
HEIGHTS INDICATE GENERALLY CLEAR CONDITIONS WILL PERSIST EAST OF THE
MOUNTAINS IN THE DOWNSLOPE FLOW. HOWEVER OVER THE MOUNTAINS TUE
NIGHT...SOME STRATO CUMULUS CEILINGS ARE LIKELY. MODEL SOUNDINGS
OVER THE MOUNTAINS INDICATE THAT ENOUGH LOW LEVEL MOISTURE WILL
PERSIST INTO THU FOR PATCHY CLOUDS.

WINDS WILL BE GUSTY IN THE MOUNTAINS TUE NIGHT AND WED IN THE COLD
ADVECTION REGIME. COOL AUTUMN TEMPS ARE EXPECTED WITH MAX TEMPS
5-10 DEGREES BELOW CLIMO ON WEDNESDAY. DESPITE THE COOL REGIME...CURRENT
INDICATIONS ARE THAT CLOUDS AND/OR WIND WILL PRECLUDE MUCH OF A
FROST FREEZE CONCERN IN THE MTNS TUE NIGHT...EXCEPT PERHAPS IN THE
SHELTERED VALLEYS OF THE SOUTHWEST MTNS (WHERE THE FROST/FREEZE
PROGRAM HAS ALREADY ENDED FOR THE SEASON). WITH WINDS DIMINISHING
WED NIGHT...A BETTER CASE CAN BE MADE FOR FROST AND AREAS
OF FREEZING TEMPS. HOWEVER....IT APPEARS THE SW MOUNTAINS WILL BE
THE COLDEST AGAIN WHILE AREAS ACROSS THE CENTRAL MOUNTAINS WHERE THE
FROST/FREEZE PROGRAM HAS NOT ENDED MAY STAY MIXED ENOUGH TO PRECLUDE
ANY FREEZE ISSUES. TEMPS WILL MODEERATE ON THU...BUT REMAIN BELOW
CLIMO.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 215 PM MONDAY...EVEN THOUGH THE 12Z GFS DEPICTS A RATHER
VIGOROUS LOOKING UPPER TROUGH MOVING SE THROUGH THE AREA THU NIGHT
INTO FRI...IT APPEARS THAT THE SYSTEM WILL BE MOISTURE STARVED AND
HENCE NO PRECIP ASSOCIATED WITH IT. MODEL TIME HEIGHTS INDICATE
PERHAPS SOME HIGH LEVEL CLOUDINESS ONLY. BEYOND THAT...AN UPPER
RIDGE IS FORECAST TO MOVE EASTWWARD FROM THE 4-CORNERS AREA TO OVER
THE EASTERN U.S. BY SUN NIGHT AND THEN OFF THE EAST COAST ON MONDAY.
SURFACE HIGH PRESSURE WILL DOMINATE THE WEATHER REGIME AS IT
EVENTUALLY MIGRATES TO OFF THE SE COAST ON MONDAY. DOWNSLOPE FLOW ON
FRIDAY LOOKS TO OVERCOME THE WEAK COLD ADVECTION ASSOCIATED WITH THE
UPPER TROUGH AND ALLOW FOR NEAR CLIMO MAX TEMPS. TEMPS WILL THEN
SLOWLY WARM TO ABOVE CLIMO THE REMAINDER OF THE PERIOD.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
AT KCLT...VFR CONDS THROUGH THE PERIOD. MID LEVEL CLOUDS ARE PUSHING
OFF TO THE EAST CURRENTLY WITH DRIER AIR MIXING IN THROUGH THE
AFTERNOON. DOWNSLOPE WARMING WILL ALLOW GOOD MIXING WITH SOME LOW
END GUST POSSIBLE THIS AFTERNOON. FEW FAIR WX CU WILL LIKELY DEVELOP
THIS AFTERNOON AS WELL...BUT NOT INCLUDED IN THE TAF ATTM. WINDS
WILL REMAIN W/LY WITH VEERING OCCURRING AFT 20Z.

ELSEWHERE...AREAS OF MORNING FG/BR DEVELOPING MAINLY ACROSS THE MTN
VALLEYS AND INTO THE NRN NC FTHILLS. KAVL SHOULD SEE A DIP INTO IFR
VSBY...WHILE KHKY WILL LIKELY BE HELD AT MVFR...BUT MAY NEED A TEMPO
IFR. MODERATE GUSTS LATE THIS AFTERNOON CONTINUING THROUGH THE
PERIOD AT KAVL AND KHKY WITH CLIPPER FRONT AND CAA PUSHING IN.
NON/MTN SITES SHOULD SEE MVFR VSBY ARND DAYBREAK WITH INCREASING
W/LY TO NW/LY WINDS MID DAY VEERING ARND 00Z.

OUTLOOK...BLUSTERY AND COOLER FOR THE MIDDLE PART OF THE WEEK...THEN
WARMING THE LATTER PORTIONS INTO THE WEEKEND. GUSTY MOUNTAIN WINDS
TUESDAY NIGHT SEEM TO BE THE ONLY AVIATION CONCERN APPARENT AT THIS
TIME...AS AIR WILL DRY AND WINDS BECOME LIGHT.

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  87%     HIGH  87%     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...HG
NEAR TERM...ARK/SBK/TS
SHORT TERM...LG
LONG TERM...LG
AVIATION...SBK






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