Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 141850
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
250 PM EDT SUN SEP 14 2014

.SYNOPSIS...
COOL BUT UNSETTLED WEATHER WILL CONTINUE THROUGH MONDAY NIGHT...AS A
STATIONARY FRONT WILL REMAIN JUST TO OUR SOUTH BEFORE AN UPPER
DISTURBANCE PASSES THROUGH. A COLD FRONT WILL THEN CROSS THE AREA IN
ITS WAKE...WHICH AGAIN STALLS TO OUR SOUTH. THIS WILL KEEP
TEMPERATURES A FEW DEGREES BELOW NORMAL INTO NEXT WEEKEND.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 245 PM...WEAK SHOWERS CONTINUED ACROSS THE I-85
CORRIDOR...ASSOCIATED WITH SURGING NE WINDS AND 305K-315K ISENTROPIC
LIFT. ISENTROPIC LIFT SHOULD GRADUALLY WEAKEN THROUGH THE REMAINDER
OF THE AFTERNOON HOURS. I WILL EXPECT LIGHT SHOWERS TO CONTINUE INTO
THIS EVENING...BUT COVERAGE SHOULD DECREASE EAST OF THE MTNS. WINDS
AT 300K SHOULD VEER FROM SOUTHEAST THIS AFTERNOON TO WEST LATE
TONIGHT. HIGH PRESSURE CENTERED OVER THE MID ATLANTIC REGION SHOULD
RESULT IN ANOTHER ROUND OF ISENTROPIC LIFT...PRIMARILY FROM 9Z-15Z. I
WILL KEEP POPS IN THE SCHC RANGE TONIGHT...WITH LOWS RANGING FROM
AROUND 60 WITHIN THE MTN VALLEYS TO THE LOW TO MID 60S EAST.

MONDAY...H85 WINDS WILL BECOME WEST DURING THE DAYLIGHT
HOURS...RESULTING IN DRYING ACROSS THE NC MTNS AND PIEDMONT.
HOWEVER...MOISTURE SHOULD REMAIN PLENTIFUL ACROSS THE SC AND GA
ZONES. THE COMBINATION OF DEEP MOISTURE AND WEAK INSTABILITY SHOULD
IN POPS RANGING FROM U40S ACROSS THE UPPER SAVANNAH RIVER VALLEY TO
SCHC ACROSS THE N I-77 CORRIDOR. THINNER CLOUD COVER AND WEAK
DOWNSLOPE WINDS SHOULD ALLOW TEMPERATURES TO REBOUND TO NEAR 80
ACROSS THE MTN VALLEYS...FOOTHILLS...AND PIEDMONT.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 215 PM SUNDAY...THINK WE ARE ENTERING A PERIOD OF DIMINISHED
CONFIDENCE IN THE FORECAST FOR THE EARLY TO MIDDLE PART OF THE WEEK.
ASSUMING A REMNANT COOL POOL HAS BEEN ELIMINATED BY MONDAY EVENING
AND SOME CONVECTION HAS DEVELOPED...IT WILL PROBABLY LINGER WELL
INTO THE EVENING IN ADVANCE OF A SHORT WAVE. THIS WAVE WILL DRIVE A
REINFORCING SURFACE BOUNDARY ACROSS THE REGION LATE MONDAY NIGHT OR
EARLY TUESDAY MORNING...BUT ITS PASSAGE IS UNREMARKABLE IN THE MODEL
GUIDANCE. THE PRECIP CHANCE HAS A DOWNWARD TREND INTO TUESDAY
MORNING ONCE THAT BOUNDARY HAS MOVED PAST. IT IS FROM THAT POINT
ONWARD THAT CONFIDENCE IS RELATIVELY LOW. THE GFS ONCE AGAIN BRINGS
THE LOW LEVEL FLOW AROUND TO EASTERLY AND UPSLOPE BEHIND THE
BOUNDARY ON TUESDAY AFTERNOON...AND DEVELOPS SOME LIGHT PRECIP
MAINLY FROM THE BLUE RIDGE EAST. THE NAM RETAINS MUCH MORE LOW LEVEL
MOISTURE AND DEVELOPS CONVECTION ON THE BLUE RIDGE AND MOVES IT
EAST. THE FORECAST IS A COMPROMISE BETWEEN THE MOSGUIDE AND THE SREF
AND WILL FEATURE A LOW END CHANCE MORE IN LINE WITH THE GFS...
FIGURING THAT EITHER WAY THERE WILL BE SOME PRECIP OUT THERE. TEMPS
REBOUND ANOTHER CATEGORY WARMER...BUT COULD BE TOO WARM IF TOO MUCH
UPSLOPE CLOUDINESS DEVELOPS EARLY IN THE DAY.

THE NEXT IN A SERIES OF WEAK HIGH PRESSURE CENTERS BRIDGES THE MTNS
TUESDAY NIGHT AND CONTRIBUTES TO THE FORMATION OF ANOTHER WEDGE-LET
BY WEDNESDAY MORNING. THE EXTENT TO WHICH YOU MIGHT CALL THIS A COLD
AIR DAMMING EVENT WILL BE DEBATABLE...AS THERE SHOULD BE NO OBVIOUS
PARENT HIGH TO THE NORTH. HOWEVER...WE SHOULD HAVE A COOL
NORTHEASTERLY FLOW AT LOW LEVELS E OF THE MTNS WHICH COULD RESULT IN
SOME LIGHT PRECIP MAINLY NEAR THE BLUE RIDGE. HAVE NUDGED THE FCST
IN THE DIRECTION OF THE SREF TO DEPICT THIS SCENARIO. TEMPS WILL
ALSO DROP OFF TWO CATEGORIES OR MORE WITH THE NORTHEAST FLOW.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 215 PM SUNDAY...THIS PERIOD BEGINS WED EVENING WITH AN UPPER
TROUGH OVER THE EAST AND A RIDGE OVER THE WESTERN STATES. ANOTHER
COLD AIR DAMMING EVENT WILL BE OCCURRING AS A 1028 MB SURFACE HIGH
WILL BE OVER THE GREAT LAKES WED EVENING AND THEN BE OVER NEW
ENGLAND THURS NIGHT. THIS SYSTEM WILL BRING A COOL AND STABLE AIR
FLOW FROM CANADA AND SOME FETCH OFF THE ATLANTIC. THIS HIGH WILL
MOVE SLOWLY EAST CROSSING NOVA SCOTIA SATURDAY MORNING WHILE STILL
RIDGING DOWN INTO THE CAROLINAS WITH A COOL NE FLOW. THIS FLOW
SHOULD CERTAINLY BREAK DOWN SUNDAY AND BECOME MORE SOUTHERLY SUNDAY
NIGHT AHEAD OF THE NEXT COLD FRONT WHICH IF FORECAST TO BE CROSSING
THE OHIO VALLEY TO START THE WEEK OF SEPTEMBER 22. THE GFS SHOWS
WEAK INSTABILITY OF AROUND 500 J/KG IN THE PIEDMONT THURS AND FRI PM
BEING MOSTLY ELBERTON TO GREENWOOD FRI...SO IF THERE IS ANY RAIN AT
ALL IT WOULD BE SHOWERS OR PATCHY LIGHT RAIN UNDER THE WEDGE. TEMPS
WILL BE THE COOLEST THURS AND FRI.  TEMPS WILL BE A BIT WARMER TO
AROUND 5 DEGREES BELOW NORMAL OVER THE WEEKEND WITH THE WEDGE
BREAKING DOWN AND THE RESULTANT OF MORE SUNSHINE.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
AT KCLT...THE 12Z NAM INDICATES THAT WEAK LLVL LIFT WILL CONTINUE
ACROSS THE TERMINAL THROUGH MOST OF THE AFTERNOON. HOWEVER...LIFT
WEAKENS CLOSER TO 0Z...I WILL INDICATE PERIODS OF VFR FROM 18-19 AS
A SHOWER PASSES BY...WITH VFR SETTLING IN AROUND 22Z. WEAK LLVL LIFT
WILL LIKELY REDEVELOP LATER TONIGHT. ONCE THE FORCING
DEVELOPS...RESTRICTIVE CEILINGS SHOULD READILY REDEVELOP ACROSS THE
REGION. I WILL INDICATE THE LOWEST CEILINGS FROM 8Z-14Z. THE ARRIVAL
OF SLIGHTLY DRIER AIR MAY ALLOW CLOUD BASES TO LIFT TO 035 BY 14Z.
THROUGH THE TAF PERIOD...WINDS WILL REMAIN BETWEEN 3-6 KTS FROM THE
NE...OR CALM. SHRA ARE MOST LIKELY THIS AFTERNOON.

ELSEWHERE...CONDITIONS WILL REMAIN SIMILAR TO KCLT. HOWEVER...SURGE
OF NE FLOW WILL KEEP KAND AND KAVL RESTRICTED THROUGH MOST OF THE
TAF PERIOD. ROUNDS OF LLVL LIFT WILL TAPER OFF THIS AFTERNOON...BUT
WILL REDEVELOP OVERNIGHT. MVFR CONDITIONS SHOULD REMAIN WIDESPREAD
THROUGH MID MORNING MONDAY. VFR CONDITIONS SHOULD SPREAD ACROSS THE
REGION BETWEEN 13Z-15Z.

OUTLOOK...THE WEDGE SHOULD MIX OUT ON MONDAY...BUT SCT
SHOWERS/THUNDERSTORMS WILL DEVELOP AHEAD OF AN APPROACHING COLD
FRONT MONDAY AFTERNOON INTO MONDAY NIGHT. A RETURN TO MAINLY VFR
CONDITIONS IS EXPECTED TUE INTO MIDWEEK OUTSIDE OF RESTRICTIONS WITH
DIURNAL CONVECTION.

CONFIDENCE TABLE...

            19-01Z        01-07Z        07-13Z        13-19Z
KCLT       HIGH  94%     HIGH  94%     MED   79%     HIGH  95%
KGSP       HIGH  83%     MED   77%     MED   72%     HIGH  81%
KAVL       HIGH  82%     MED   68%     HIGH  90%     HIGH  87%
KHKY       HIGH  94%     HIGH  91%     MED   73%     HIGH  95%
KGMU       HIGH  81%     MED   79%     MED   73%     HIGH  86%
KAND       HIGH  92%     HIGH  87%     HIGH  91%     HIGH  93%

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...DEO
NEAR TERM...NED
SHORT TERM...PM
LONG TERM...DEO
AVIATION...NED





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