Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 150200
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1000 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/...
AT 1000 PM EDT SUNDAY...A BROAD LOW AMPLITUDE UPPER TROUGH EXTENDED
ACROSS THE NORTH CENTRAL PART OF THE NATION...WHILE A FLAT UPPER
RIDGE EXTENDED FROM TX TO THE GA COAST. A WEAK IMPULSE MOVING
THROUGH THE UPPER TROUGH WILL PASS TO THE NORTH OF NC OVERNIGHT.
SURFACE ANALYSIS PLACED A STATIONARY FROM THE GA COAST TO THE
NORTHERN GULF OF MEXICO. CONVECTIVE ACTIVITY WAS LOCATED ALONG THIS
BOUNDARY.

COOLER AIR NORTH OF THE FRONT EXTENDED ACROSS THE WESTERN CAROLINA
AND NE GA. ISOLATED SHOWERS MOVING NORTHEAST ALONG INTERSTATE 85
HAVE LARGELY ABATED THIS EVENING. WITH SOME WEAK ISENTROPIC UPGLIDE
REMAIN OVER OUR AREA...VERY SMALL POPS WILL REMAIN IN THE FORECAST
OVERNIGHT. MODEL GUIDANCE SUPPORTS FOG LATE TONIGHT...BUT ONLY HAD
SIGNIFICANT REDUCTIONS IN VISIBILITY IN THE MOUNTAINS. WITH LOW
CONFIDENCE IN DENSE FOG...NO ADVISORY WILL BE ISSUED AT THIS TIME.
MINIMUM TEMPERATURES WILL RUN SLIGHTLY ABOVE NORMAL DUE TO CLOUDS
AND LINGERING LOW LEVEL MOISTURE.

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 /02Z MONDAY THROUGH FRIDAY/...
AT KCLT...GUIDANCE DOES NOT FAVOR A VSBY RESTRICTIONS...EVEN THROUGH
NE WINDS FALL OFF CONSIDERABLY. GUIDANCE DOES FAVOR MVFR CIGS
OVERNIGHT...WITH A RETURN TO VFR IN THE MORNING. CONVECTIVE CHANCES
WILL INCREASE ON MONDAY AS COOL HIGH PRESSURE WEAKENS...AND WARRANT
A MENTION IN THE TAF. LIGHT NE WINDS WILL VEER SW BY MONDAY
AFTERNOON.

ELSEWHERE...GUIDANCE FAVORS MVFR VSBY IN THE FOOTHILLS...AND LIFR IN
AT KAVL. WITH CONFIDENCE STILL SOMEWHAT LIMITED...DESPITE LIGHT
WINDS OVERNIGHT...ONLY IFR WILL BE CARRIED AT KAVL...AND HIGH END
MVFR AT FOOTHILL SITES. GUIDANCE SUPPORTS MVFR CIGS OVERNIGHT...AND
LIFR AT KAVL BY DAWN. ALTHOUGH VSBY RETURNS TO VFR MID MORNING...BUT
CIGS ARE NOT EXPECTED TO RETURN TO VFR UNTIL MIDDAY. LIGHT NE WINDS
WILL VEER SW BY MONDAY AFTERNOON IN THE FOOTHILLS... WHILE KAVL
WINDS VEER FORM N TO S. CONVECTIVE CHANCES INCREASE ON
MONDAY...WARRANTING A MENTION IN THE TAFS BY AFTERNOON.

OUTLOOK...SCT SHOWERS/THUNDERSTORMS WILL CONTINUE INTO MONDAY NIGHT.
A RETURN TO MAINLY VFR CONDITIONS IS EXPECTED TUE INTO MIDWEEK
OUTSIDE OF RESTRICTIONS WITH DIURNAL CONVECTION.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-02Z
KCLT       HIGH  81%     MED   64%     HIGH  92%     HIGH 100%
KGSP       HIGH  90%     HIGH  97%     HIGH  94%     HIGH  91%
KAVL       MED   77%     HIGH  92%     HIGH  83%     HIGH  96%
KHKY       MED   74%     HIGH  80%     HIGH  93%     HIGH  98%
KGMU       HIGH  85%     HIGH  92%     HIGH  95%     HIGH 100%
KAND       HIGH  80%     HIGH  83%     HIGH  90%     HIGH  91%

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...JAT/NED
SHORT TERM...PM
LONG TERM...DEO
AVIATION...JAT





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