Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 280826
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
326 AM EST FRI NOV 28 2014

.SYNOPSIS...
DRY HIGH PRESSURE WILL BUILD ACROSS THE REGION TODAY AND LINGER
THROUGH THE WEEKEND. THEN A COLD FRONT WILL PUSH THROUGH THE
FORECAST AREA FROM THE NORTH EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM...LATEST IR SATELLITE IMAGES CONTINUED TO INDICATE
CLOUD TOP TEMPERATURES AS COOL AS -15 TO -17C ACROSS THE NORTHERN NC
MTNS. RADAR INDICATED A WEAKENING AREA OF LIGHT RETURNS ACROSS
EASTERN TN. HOWEVER...SFC OBS AND WEB CAMS INDICATED THAT LIGHT SNOW
TO FLURRIES WAS FALLING UNDER THE COOLEST CLOUD TEMPS. IT APPEARS
THAT THE GUSTY NORTHWEST WINDS SUPPORTING THE UPSLOPE CLOUDS AND
LIGHT SNOW WILL REMAIN OVER THE NEXT THREE HOURS...I WILL ADJUST
POPS AND WX.

AFTER SUNRISE...THE CENTER OF A 1030 MB HIGH WILL SLIDE ACROSS THE
SOUTHERN APPALACHIANS...RESULTING IN WEAKENING WINDS. BY THE
AFTERNOON...A WEAK TROF IS EXPECTED TO DEVELOP ACROSS THE EAST
FACING SLOPES AND ADJACENT FOOTHILLS. AFTERNOON WINDS ARE FAVORED
FROM THE SW ACROSS THE PIEDMONT AND FOOTHILLS. I WILL FORECAST
MOSTLY SUNNY CONDITIONS WILL PM RH IN THE 30S.  A BLEND OF
TEMPERATURE GUIDANCE SUPPORTS HIGHS IN THE LOW 40S WITHIN THE MTN
VALLEYS TO MID TO UPPER 40S EAST.

TONIGHT...THE HIGH CENTER IS EXPECTED TO SLIDE OVER THE CAROLINA
COAST BY 12Z. WINDS SHOULD BECOME CALM TO LIGHT FROM THE SOUTH
OVERNIGHT. FORECAST SOUNDINGS INDICATE THAT THIN HIGH CLOUDS WILL
GRADUALLY INCREASE DURING THE LATE NIGHT HOURS. WEAK LLVL
TEMPERATURE RECOVERY AND THIN CLOUDS MAY PROVIDE TEMPS A COUPLE OF
DEGREES WARMER THAN THIS MORNING. I WILL FORECAST LOWS RANGING FROM
THE MID 20S WITHIN THE VALLEYS TO AROUND 30 EAST.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 245 AM FRIDAY...THE SHORT TERM PERIOD LOOKS FAIRLY QUIET. THE
UPPER FLOW WILL START OUT HIGHLY ZONAL ON SATURDAY...THEN A TROF
WILL DIG INTO THE NORTHERN PLAINS AND UPPER MIDWEST SUNDAY...WHILE
AN UPPER RIDGE BUILDS ACRS THE SOUTHEAST STATES.

AT THE SFC...A MODERATING CANADIAN AIR MASS WILL SHIFT EAST OFF THE
EAST COAST ON SATURDAY...WHILE A COLD FRONT DROPS INTO GREAT LAKES
AND CENTRAL PLAINS. THE HIGH SETTLES ACRS THE SUBTROPICAL LATITUDES
FOR SUNDAY AND MONDAY...ALLOWING AN INCREASING WEST-SOUTHWESTERLY
LLVL FLOW TO PERSIST ACRS THE CWFA. OTHER THAN SOME MOISTURE AND
POSSIBLE SHWRS APPROACHING THE NC/TN BORDER AHEAD OF AN APPROACHING
FRONT...THE FA SHUD BE DRY...WITH A NICE WARMING TREND. TEMPS WILL
START OUT NEAR OR SLIGHTLY BELOW NORMAL SATURDAY...THEN WARM SEVERAL
DEG SUNDAY...AND EVEN WARMER ON MONDAY...WITH UPPER 60S POSSIBLE
ACRS THE PIEDMONT.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 300 AM FRIDAY...MODELS IN DECENT AGREE TO START OUT THE MEDIUM
RANGE...DEPICTING A COLD FRONT PUSHING THRU THE AREA MONDAY
EVENING...USHERING IN FAIRLY STRONG COLD AIR DAMMING EAST OF THE
MTNS BY DAYBREAK TUESDAY. THE PARENT HIGH OF THE CAD...WITH BE
FAST-MOVING...BUT STRONG...BUILDING TO ABOUT 1043 MB...AS IT CROSSES
THE GREAT LAKES MONDAY NIGHT...TO INVOF NEW BRUNSWICK BY TUESDAY
EVENING. GIVEN THE TRENDS...I HAVE BUMPED MONDAY NIGHT AND TUESDAY
TEMPS DOWN ABOUT 5 DEG OR SO. THE GFS IS A LITTLE STRONGER AND
COLDER THAN THE ECWMF...BRINGING POTENTIALLY FREEZING RAIN
THICKNESSES EARLY TUESDAY MORNING TO NEAR I-40. FOR NOW...I STILL
HAVE NO WINTRY PRECIP MENTION IN THE GRIDS. HOWEVER...IF MODELS
TREND MUCH COLDER...THERE MAY BE A CHC OF VERY LIGHT AND GENERALLY
SPOTTY ICE ACCUM TUESDAY MORNING.

FROM TUESDAY NIGHT THRU THURSDAY...THE GFS AND ECWMF BEGIN TO
DIVERGE...AND THE OVERALL TRENDS ARE MIXED. THEY BOTH TAKE THE
PARENT HIGH OF THE CAD ACRS THE CANADIAN MARITIMES ON
WEDNESDAY...AND ALLOW THE WEDGE TO ERODE BY WEDNESDAY AFTN. I
SUPPOSE WITHOUT MUCH FORCING AND LACK QPF RESPONSE IN THE
MODELS...THERE MAY NOT BE ANY WAY TO ANCHOR THE WEDGE. WITH THAT
SAID...MODELS ARE NOTORIOUS FOR ENDING CAD EVENTS TOO EARLY. WHETHER
THE WEDGE PERSISTS OR NOT...850 MB TEMPS CONTINUE TO RISE TO AROUND
6-8C. SO ANY PRECIP THAT MAY OCCUR SHUD BE ALL RAIN. THE ECWMF
PUSHES A COLD FRONT THRU THE AREA WEDNESDAY NIGHT...BRINGING PERHAPS
A SMALL CHC OF SHWRS ALONG THE TN/NC BORDER. WHILE THE GFS WASHES
THE FRONT OUT TO OUR NORTH AND KEEPS US IN A WARMER AIR MASS. IN
LIGHT OF THE DISAGREEMENT...I DID NOT MAKE MAJOR CHANGES TO THE
GRIDS FOR THESE PERIODS. KEEPING NEAR NORMAL TEMPS AND GRADUALLY
TAPERING POPS.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS. STEADY NORTHWEST FLOW WILL
CONTINUE ACROSS THE REGION EARLY THIS MORNING. UPSLOPE CLOUDS ARE
FORECAST TO CONTINUE ALONG THE TN LINE THROUGH SUNRISE. CLOUDS AND
FLURRIES MAY REACH KAVL FROM TIME TO TIME THROUGH 9Z...THEN EXPECTED
TO SLIDE WEST AS FLOW WEAKENS DURING THE PRE DAWN HOURS. THE CENTER
OF HIGH PRESSURE WILL SLIDE ACROSS THE WESTERN CAROLINAS DURING THE
DAYLIGHT HOURS FRIDAY...LIKELY WITH A WEAK LEE TROUGH. WINDS WILL
BECOME LIGHT FROM THE SOUTHWEST BY FRIDAY AFTERNOON.

OUTLOOK...DRY HIGH PRESSURE WILL SET UP OVER THE AREA THROUGH THE
WEEKEND. A COLD FRONT WILL APPROACH FROM THE NORTHWEST EARLY NEXT
WEEK.

CONFIDENCE TABLE...

            08-14Z        14-20Z        20-02Z        02-06Z
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...ARK
NEAR TERM...NED
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...NED


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