Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 251434
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1034 AM EDT MON APR 25 2016

.SYNOPSIS...
HIGH PRESSURE WILL SET UP OFF THE EAST COAST THROUGH
WEDNESDAY...ALLOWING SOUTHWESTERLY FLOW TO BRING INCREASING MOISTURE
BACK INTO THE REGION. A WEAK COLD FRONT WILL CROSS THE AREA ON
THURSDAY. WARM AND DRY HIGH PRESSURE RETURNS FOR FRIDAY AND SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM...CUMULUS CLOUDS FORMING NEARLY AS EXPECTED THIS
MORNING. EXPECT COVERAGE TO CONTINUE TO INCREASE THRU THE DAY WITH
BEST COVERAGE OVER THE MOUNTAINS. LATEST GUIDANCE SHOWS A SLIGHTLY
BETTER CHANCE OF CONVECTION ACROSS THE NORTHERN MOUNTAINS AND BLUE
RIDGE. HAVE INCREASED POP SLIGHTLY THERE. OTHERWISE...GOING FORECAST
REMAINS ON TRACK.

THE LOW LEVEL ANTICYCLONE CENTER WILL CONTINUE TO MIGRATE OFF THE
SOUTHEAST COAST THROUGH THE NEAR TERM PERIOD...PERMITTING LOW LEVEL
MOISTURE TO GRADUALLY RETURN TO THE SOUTHERN APPALACHIANS AND
SURROUNDING AREAS. THIN HIGH CLOUDS MOVING IN ALOFT WILL BE
ACCOMPANIED BY A SLOWLY IMPROVING CONVECTIVE CUMULUS FIELD THROUGH
THE DAY...BUT THE CLOUDS WILL NOT SIGNIFICANTLY IMPACT HEATING WITH
MAXES REACHING AROUND 5 DEGREES ABOVE CLIMO. VERY MARGINAL
INSTABILITY SHOULD BE REALIZED WITH THE INSOLATION TODAY...GENERALLY
LIMITED TO A FEW HUNDRED J/KG OF SBCAPE THIS AFTERNOON AND EVENING
OVER THE MOUNTAINS. THE LIGHT SOUTHERLY UPSLOPE FLOW COULD TRIGGER
ISOLATED TO SCATTERED SHOWERS OR EVEN A FEW THUNDERSTORMS...BUT
NOTHING TOO STRONG.

MIN TEMPS TONIGHT WILL REBOUND ANOTHER 2 TO 4 DEGREES OVER THIS
MORNING AS THE AIRMASS CONTINUES TO MODIFY ALONG WITH GRADUALLY
INCREASING ATLANTIC MOISTURE IN THE BOUNDARY LAYER. ISOLATED SHOWERS
IN THE UPSLOPE FLOW COULD LINGER THROUGH THE EVENING MAINLY IN THE
SW MOUNTAINS.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 230 AM MONDAY...A FLAT AND BROAD UPPER RIDGE WILL PERSIST
ACROSS THE SOUTHEAST STATES THRU THE SHORT TERM...BEING PINCHED
BETWEEN A BROAD UPPER TROUGH OVER THE GREAT LAKES AND THE
NORTHEAST...AND A DEEP LARGE UPPER LOW EJECTING INTO THE GREAT
PLAINS. AT THE SURFACE...A SUBTROPICAL HIGH WILL SET UP ATOP THE
REGION...AND GRADUALLY TAP INTO MORE GULF MOISTURE THRU THE PERIOD.
WITH THE INCREASING MOISTURE...THERE WILL BE A GRADUAL INCREASE IN
CAPE. HOWEVER...THERE WILL BE A LACK OF FORCING...WITH A BACKDOOR
COLD FRONT STALLING JUST TO OUR NORTH. I WILL FORECAST INCREASING
POP EACH PERIOD FROM TUESDAY THRU WEDNESDAY NIGHT. TEMPS WILL TOP
OUT IN THE LOW 80S TUESDAY AND MID 80S WEDNESDAY EAST OF THE MTNS.
OVERNIGHT LOW TEMPS WILL BE WELL ABOVE NORMAL (50S MTNS AND 60S
PIEDMONT).

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 245 AM MONDAY...A LARGE UPPER LOW OVER THE PLAINS WILL LIFT NE
AND SHEAR OUT OVER THE GREAT LAKES...AS THE SUBTROPICAL RIDGE OVER
THE SOUTHEAST STATES PERSISTS. A WEAK LOW PRESSURE SYSTEM WILL TRY
TO MAKE INROADS EAST ACROSS THE OH/TN VALLEYS TO THE APPALACHIANS
THURSDAY. THERE MAY BE ENOUGH FORCING WITH THE DYING FRONT TO
TRIGGER MORE WIDESPREAD CONVECTION ACROSS THE CWFA. THE GFS AND
ECMWF AGREE ON ABOUT 1000-1500 J/KG OF SBCAPE ON THURSDAY...BUT ONLY
WITH 25-30 KTS OF 0-6 KM BULK SHEAR. SO WHILE WE WILL HAVE SOLID CHC
TO LIKELY POPS...THE SEVERE THREAT LOOKS MARGINAL. TEMPS WILL STILL
BE ABOUT 8-10 DEG ABOVE NORMAL DESPITE MORE CLOUDS AND PRECIP
THURSDAY. LOWS WILL BE ABOUT 10-15 DEG ABOVE NORMAL.

FRIDAY THRU SUNDAY...WEAK HIGH PRES WILL BUILD IN BEHIND THE
FRONT...WITH DOWNSLOPE NW FLOW HELPING TEMPS WARM BACK TO ABOUT 8-10
DEG ABOVE NORMAL (MID 80S EAST OF THE MTNS). THEN POPS WILL
GRADUALLY RAMP UP AGAIN OVER THE WEEKEND TO LIKELY...AS AN AREA OF
LOW PRESSURE ORGANIZES OVER THE SOUTHERN PLAINS. THE 00Z GFS/ECWMF
ARE IN GOOD AGREEMENT ON A MOIST COLD AIR DAMMING WEDGE SETTING UP
BY SUNDAY. TEMPS WILL TREND COOLER TOWARD NORMAL BY SUNDAY.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
AT KCLT AND ELSEWHERE...BOUNDARY LAYER MOISTURE WILL GRADUALLY
INCREASE THROUGH THE TERMINAL FORECAST PERIOD AS SOUTHERLY FLOW
CONTINUES AROUND OFFSHORE HIGH PRESSURE. THE PLUME OF MVFR CLOUDS
FROM KCLT TO THE SW WILL DISSIPATE/LIFT THROUGH THE MORNING.
OTHERWISE...MAINLY SCATTERED VFR LEVEL CUMULUS WILL DEVELOP WITH
HEATING...BUT BRIEF VFR OR ISOLATED MVFR CIGS WILL CONTINUE TO BE
POSSIBLE IN THE SOUTHWEST MOUNTAINS IN THE BEST REGION OF UPSLOPE
THROUGH LATE MORNING AND INTO EARLY AFTERNOON. WILL KEEP CLOUDS
SCATTERED AT THE TAF SITES...EXCEPT VFR CIGS DEVELOPING FROM KAVL TO
KAND BY THIS EVENING. EXPECT LIGHT S TO SW WINDS EARLY THIS MORNING.
A FEW LOW END GUSTS WILL BE POSSIBLE WITH THE DEEPEST MIXING THIS
AFTERNOON BEFORE WINDS SLACKEN AND BACK TO S OR SE AGAIN THIS
EVENING. ANY AFTERNOON SHOWERS SHOULD FORM MAINLY OVER THE MOUNTAINS
BUT WITH CHANCES TOO LOW TO MENTION AT KAVL.

OUTLOOK...INSTABILITY WILL INCREASE ACROSS THE REGION TUESDAY
THROUGH WEDNESDAY AS A BACK DOOR COLD FRONT APPROACHES FROM THE
NORTH. PRECIPITATION CHANCES WILL INCREASE INTO THURSDAY AHEAD OF A
COLD FRONT TO THE NORTHWEST...WITH UNSETTLED WEATHER POSSIBLE INTO
FRIDAY.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
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  92%
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 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...ARK
NEAR TERM...HG/RWH
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...HG/RWH



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