Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 231503
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1103 AM EDT SAT APR 23 2016

.SYNOPSIS...
A WEAK PASSING COLD FRONT WILL MOVE SOUTH OF THE AREA TODAY WITH DRY
HIGH PRESSURE BUILDING OVER THE REGION FROM THE NORTH THROUGH
SUNDAY. AS THE HIGH PRESSURE MOVES OFFSHORE EARLY IN THE
WEEK...SOUTHWESTERLY FLOW WILL ALLOW MOISTURE TO GRADUALLY RETURN
ACROSS THE SOUTHERN APPALACHIANS. A BACK DOOR COLD FRONT WILL
APPROACH FROM THE NORTH TUESDAY NIGHT AND LIKELY STALL SOMEWHERE IN
THE VICINITY ON WEDNESDAY BEFORE RETURNING NORTH AS A WARM FRONT
THROUGH LATE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1050 AM EDT SATURDAY...WITH A COLD FRONT WELL TO THE
SOUTH...THE ATM CONTINUES TO DRY OUT ACROSS THE LOW TERRAIN
WHERE VISSAT CURRENTLY INDICATES ONLY A FEW LOW CU...WITH THE
FCST CONTINUING TO FAVOR INCREASING/LIFTING CU.  FURTHER WEST
ACROSS THE MTNS ITS A DIFFERENT STORY AS NW UPSLOPE FLOW IS
LIFTING LLV MOISTURE AND THUS PRODUCING STRATOCU...WHICH IS
STILL EXPECTED GRADUALLY ERODE THROUGHOUT THE AFTERNOON/EVENING.
WINDS HAVE INCREASED WITH LOW END GUSTS PREVAILING THROUGH THE DAY.
CURRENT FCST REMAINS ON TRACK THUS SO CIG CHANGES WERE MADE.

A MID LEVEL TROUGH WILL SHIFT EAST OF THE AREA BY LATE
MORNING...ALLOWING SKIES TO CLEAR OUT...SAVE FOR SOME LINGERING
NW FLOW UPSLOPE CLOUDS ALONG THE TN BORDER. A WEAK COLD FRONT WILL
EXIT TO THE EAST...AS A MODEST SFC RIDGE BUILDS SOUTHWARD ACRS THE
OH/TN VALLEYS. SOME DRIER AIR WILL FILTER IN FROM THE NORTH...AND
WITH THE HELP OF SOME LIGHT NWLY DOWNSLOPE FLOW...EXPECT TEMPS TO
REBOUND TO ABOUT A CATEGORY ABOVE NORMAL TODAY.

TONIGHT...DRY HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE NW.
THE NAM AND GFS HINT AT SOME HIGH-BASED STRATUS DEVELOPING TOWARD
DAYBREAK SUNDAY...AS SOME RH AT 850 MB REMAINS TRAPPED UNDER THE
BUILDING RIDGE. THE FLOW LOOKS WEAK...BUT DOES TURN OUT OF THE
EAST FOR A WHILE AFTER 06Z TONIGHT. WILL GO WITH MOSTLY CLEAR
SKIES FOR TONIGHT. MIN TEMPS WILL BE ABOUT A CATEGORY ABOVE NORMAL.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
AS OF 315 AM EDT SATURDAY...A 500 MB RIDGE AXIS WILL SETTLE OVER THE
SE ON SUNDAY AS DRY SURFACE HIGH PRESSURE NOSES DOWN FROM THE NORTH.
MAX TEMPS WILL CONTINUE TO REBOUND TO SLIGHTLY ABOVE CLIMO VALUES
WITH 70S THROUGHOUT.

THE UPPER FLOW PATTERN WILL THEN BECOME INCREASINGLY ZONAL ON MONDAY
AS PHASING LOW PRESSURE LIFTS OVER THE EASTERN RIDGE INTO THE GREAT
LAKES. THE SURFACE HIGH WILL MIGRATE OFFSHORE AND PERMIT
SOUTHWESTERLY WINDS TO START MODIFYING THE AIRMASS AND SLOWLY
BRINGING BOUNDARY LAYER MOISTURE BACK TOWARD THE BASE OF THE
SOUTHERN APPALACHIANS. MAX TEMPS WILL RECOVER ANOTHER 1 TO 2
CATEGORIES...WITH LOW 80S EAST OF THE MOUNTAINS. AN ISOLATED LATE
DAY NORTHERN/WESTERN MOUNTAIN SHOWER CANNOT BE RULED OUT.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
AS OF 315 AM EDT SATURDAY...THE UPPER RIDGE WILL BECOME RESURGENT
OVER THE FORECAST AREA TUE THROUGH WED AS A STRONG CLOSED LOW MOVES
FROM THE ROCKIES INTO THE PLAINS. AT LOWER LEVELS...A BACKDOOR COLD
FRONT WILL SAG SOUTHWARD INTO OR NEAR THE FORECAST AREA TUE NIGHT
INTO WED. LATE TUESDAY INSTABILITY MAY MAXIMIZE ACROSS THE NORTHERN
TIER AHEAD OF THE APPROACHING BOUNDARY AND ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS ARE POSSIBLE OVER THE MOUNTAINS AND NORTH
OF INTERSTATE 40. THE WARMUP WILL CONTINUE WITH PLENTY OF MID 80S
HIGHS TUE AFTERNOON. WEDNESDAY TEMPS ARE A BIT MORE OF QUESTION MARK
DEPENDING ON HOW FAR SOUTH THE STALLING BOUNDARY GETS. WILL ALSO
MAKE ISOLD TO SCATTERED CONVECTION A BIT MORE EXPANSIVE ON WED WITH
THE BOUNDARY IN THE REGION.

ZONAL FLOW WILL SET UP AGAIN THU THROUGH FRI...WITH ANY ENERGY FROM
THE PLAINS SYSTEM PASSING TO THE NORTH. DEPENDING ON THE LOCATION OF
THE STALLED BACK DOOR FRONT...MOIST UPGLIDE COULD DEVELOP OVER THE
BOUNDARY ON THU. THE GFS IS MOST AGGRESSIVE AT KEEPING UPGLIDE IN
PLACE OVER THE AREA WHEREAS THE ECMWF HAS THE BOUNDARY NORTH OF THE
REGION. A BLEND IS PREFERRED GIVEN ALL THE UNCERTAINTY AND THIS WILL
PERMIT MORE 80S TEMPS EAST OF THE MOUNTAINS THU AFTERNOON BUT WITH
YET ANOTHER UPTICK IN POP. BETTER INSTABILITY IS THEN LIKELY ON
FRIDAY AS THE TRAILING COLD FRONT SETTLES INTO THE AREA WHILE THE
WARM SECTOR EXPANDS FROM THE SOUTH.

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...FOG AND STRATUS IS BEING SCOURED OUT FROM NW
TO SE ACROSS THE PIEDMONT EARLY THIS MORNING...AS A COLD FRONT HAS
JUST PASSED THROUGH THE AREA. BY 12Z VALID TIME ALL SITES MAY BE
VFR. KCLT AND KAND MAY HAVE BRIEF RESTRICTIONS DURING THE FIRST HOUR
OF THE TAF...SO WILL TEMPO IN SOME IFR. OTHERWISE...VFR CONDITIONS
ARE EXPECTED THRU THE PERIOD. N TO NW WINDS WILL INCREASE BY MID
MORNING...WITH LOW-END GUSTS EXPECTED THRU THE AFTN. THEN THE NW
WINDS DIMINISH AROUND SUNSET. GUIDANCE IS BACKING OFF SOME
HIGH-BASED STRATOCU DEVELOPMENT TONIGHT. I WILL ADD A FEW050 MENTION
AT KCLT AFTER 06Z. BUT OTHERWISE...SHOULD BE SKC OR FEW-SCT250.

OUTLOOK...HIGH PRESSURE AND MOSTLY VFR CONDITIONS WILL PERSIST INTO
MONDAY. PRECIPITATION CHANCES WILL START TO INCREASE ON TUESDAY.

CONFIDENCE TABLE...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH  85%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  83%
KHKY       HIGH  85%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     MED   70%     LOW   57%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...HG
NEAR TERM...ARK/CDG
SHORT TERM...HG
LONG TERM...HG
AVIATION...ARK



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