Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 281738
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1238 PM 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 1235 PM...SAT PIX SHOW LOW CLOUDS HAVE DISSIPATED ACROSS THE
MTNS WHILE MTN WAVE CIRRUS IS DEVELOPING. THE CIRRUS SHOULD REMAIN
MOSTLY THIN...BUT WILL INCREASE IN COVERAGE THRU THE AFTERNOON THEN
DISSIPATE OVERNIGHT. WINDS ARE BEGINNING TO TURN SWLY ACROSS THE
AREA AS A HIGH PRESSURE CENTER MOVES EAST OF THE AREA. HOWEVER...
WINDS WILL REMAIN WLY TO NLY ACROSS THE MTNS. FCST HIGHS STILL LOOK
ON TRACK.

AS OF 935 AM...SAT PIX SHOW LOW CLOUDS SLOWLY DISSIPATING ACROSS THE
NC MTNS WHILE MID AND HIGH CLOUDS MOVE IN FROM THE NW. EXPECT THE
LOW CLOUDS TO CONTINUE TO SLOWLY ERODE WHILE THE MID AND HIGH CLOUDS
INCREASE IN COVERAGE AND THICKNESS INTO EARLY AFTERNOON. THE CLOUDS
THEN SLIDE EAST AND MOVE OUT OF THE AREA DURING THE EVENING. STILL
EXPECT THE LIGHT NLY WIND OUTSIDE OF THE MTNS TO BECOME LIGHT SWLY
THIS AFTERNOON...WHILE THE N TO NW WINDS CONTINUE ACROSS THE MTNS.
FCST HIGH TEMPS STILL LOOK ON TRACK.

AS OF 530 AM...RECENT DATA REVEALED WARMING CLOUD TOPS ACROSS THE TN
BORDER. IN ADDITION...NO RADAR RETURNS WERE ACROSS EAST TN AND
OBSERVATIONS OF SNOW ACROSS THE NRN MTNS HAVE ENDED. I WILL UPDATE
THE FORECAST TO REDUCE CLOUD COVER AND POPS. TEMPS...DEWPOINTS...AND
WINDS REMAIN ON TRACK.

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 /18Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...THE CENTER OF HIGH PRESSURE HAS MOVED EAST
OF THE AREA BRINGING THE LIGHT WINDS TO A SWLY DIRECTION...EXCEPT AT
KAVL WHERE WINDS REMAIN NLY. THESE WINDS WILL CONTINUE INTO EARLY
EVENING WHEN CALM WINDS ARE EXPECTED. S TO SW WINDS PICK BACK UP
AGAIN SAT MORN...BUT SPEEDS WILL BE A LITTLE HIGHER. MTN WAVE CIRRUS
THIS AFTERNOON WILL SCATTER OUT OVERNIGHT...BUT RETURN SAT AS HIGH
LEVEL MOISTURE RETURNS ALONG WITH AN UPPER JET STREAK. NO VSBY
RESTRICTIONS EXPECTED THRU THE PERIOD.

OUTLOOK...LOW CLOUDS ARE POSSIBLE SUNDAY MORNING IN THE MOIST SLY
FLOW AHEAD OF A COLD FRONT. THE FRONT WILL SLOWLY SLIP SOUTH ACROSS
THE SOUTHERN APPALACHIANS ON MONDAY. ON TUESDAY...A STRONG RIDGE OF
HIGH PRESSURE WILL BUILD ACROSS THE REGION WITH INCREASING LOW LEVEL
MOISTURE...LIKELY RESULTING IN WIDESPREAD CEILING RESTRICTIONS
THROUGH MID WEEK.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
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/RWH
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...RWH


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