Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 250710
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
310 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 230 AM EDT...THE SURFACE TO 850 MB ANTICYCLONE CENTER WILL
MIGRATE OFF THE SOUTHEAST COAST THROUGH THE NEAR TERM
PERIOD...PERMITTING LOW LEVEL MOISTURE TO GRADUALLY RETURN TO THE
SOUTHERN APPALACHIANS AND THE SURROUNDING REGION. 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 /07Z 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. MAINLY VFR LEVEL SCATTERED
CUMULUS WILL DEVELOP WITH HEATING...BUT BRIEF VFR OR ISOLATED MVFR
CIGS WILL BE POSSIBLE IN THE SOUTHWEST MOUNTAINS IN THE BETTER
REGION OF UPSLOPE THIS MORNING. WILL KEEP ALL CLOUDS SCATTERED AT
THE TAF SITES HOWEVER. EXPECT LIGHT S TO SE WINDS EARLY THIS MORNING
TO TURN MORE SW WITH MIXING THROUGH LATE MORNING AT ALL SITES EXCEPT
KAVL. ANY AFTERNOON SHOWERS SHOULD FORM MAINLY OVER THE MOUNTAINS
BUT WITH CHANCES TOO LOW TO MENTION AT KAVL. 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.

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...

            07-13Z        13-19Z        19-01Z        01-06Z
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  99%     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
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...HG



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