Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 271454
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1054 AM EDT WED MAY 27 2015

.SYNOPSIS...
A BERMUDA HIGH PATTERN WILL PERSIST ACROSS THE REGION FOR THE REST
OF THIS WEEK. THEN A WEAK COLD FRONT WILL PUSH INTO THE AREA AND
STALL EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM...WIDESPREAD STRATUS PERSISTS ACROSS THE PIEDMONT AND
FOOTHILLS THIS MORNING...WITH JUST A FEW BREAKS SHOWING HERE AND
THERE. MEANWHILE...VALLEY FOG/LOW STRATUS HAS BURNED OFF ACROSS MOST
OF THE MTN VALLEYS...AND THE VAST MAJORITY OF THE MTNS ARE
EXPERIENCING MOSTLY SUNNY SKIES ATTM. THIS CREATES SOMEWHAT OF A
CONUNDRUM IN TERMS OF DEEP CONVECTIVE CHANCES THIS PM...AS IT/S NOT
ENTIRELY CLEAR EXACTLY WHEN THE PIEDMONT STRATUS WILL BURN OFF...
AND THUS JUST HOW MUCH INSTABILITY WILL BE REALIZED THERE. A FEW
SHOWERS HAVE DEVELOPED ACROSS THE EASTERN ZONES THIS MORNING...AS
WAS SUGGESTED BY THE SHORT TERM AND SOME MESOSCALE MODEL GUIDANCE
(HOWEVER...NOT NEARLY TO THE EXTENT AS WAS SUGGESTED BY SAID
MODELS). THIS ACTIVITY IS FIRING WITHIN A PLUME OF DEEPER
MOISTURE...WHICH IS EXPECTED TO SHIFT EAST OF THE FORECAST AREA THIS
AFTERNOON. AS SUCH...THERE IS A FAIRLY CLEAR CONSENSUS IN THE
MESOSCALE/CONVECTION ALLOWING MODEL GUIDANCE THAT THERE WILL NOT BE A
GREAT DEAL OF DEEP CONVECTIVE COVERAGE...ESP OUTSIDE THE MTNS. THIS
CERTAINLY MAKES SENSE IN LIGHT OF THE DELAY IN DESTABILIZATION THAT
IS UNDERWAY ACROSS THE PIED/FHILLS. THE UPSHOT IS THAT POPS HAVE
BEEN RAISED A BIT ACROSS THE MTNS...ESP NEAR THE BLUE RIDGE...AND
DECREASED A BIT ACROSS THE PIED/FHILLS. THIS GENERALLY RESULTED IN
WIDESPREAD 30 POPS...WITH A COUPLE OF POCKETS OF 20 AND 40 (HIGHEST
NEAR THE ESCARPMENT).

BULK SHEAR WILL BE VERY WEAK THIS PM (GENERALLY LESS THAN 10 KTS) IN
THE 0-3KM AND 0-6KM LAYERS)...THUS CHANCES FOR UPSCALE ORGANIZATION
WILL BE VERY LOW. HOWEVER...DRYING ALOFT SHOULD RESULT IN
RESPECTABLE LEVELS OF DCAPE THIS AFTERNOON...WHICH SHOULD POSE A
THREAT OF ISOLATED PULSE STORMS/BRIEF MICROBURST-PRODUCERS IN THE
WEAKLY SHEARED ENVIRONS.

AS OF 650 AM...RADAR REMAINS PPINE THIS MORNING AND ANY CONVECTION
SHUD HOLD OFF UNTIL AFTERNOON. HAVE UPDATED POP TO REFLECT THIS.
PATCHY FOG SHUD BURN OFF QUICKLY THIS MORNING...BUT LOW CLOUDS WILL
ONLY SLOWLY LIFT AND/OR SCATTER OUT BY EARLY AFTERNOON. OTHERWISE...
FCST MAINLY ON TRACK WITH UPDATES NEEDED FOR CURRENT CONDITIONS.

AS OF 325 AM...SHRA HAVE DISSIPATED AND LOW CLOUDS AND FOG ARE
DEVELOPING IN ITS PLACE. THAT SAID...CANNOT RULE OUT A SPRINKLE OR
TWO HERE AND THERE EARLY THIS MORNING. THE FOG WILL BURN OFF BY MID
MORNING WHILE THE LOW CLOUDS WILL ONLY SLOWLY LIFT INTO THE EARLY
AFTERNOON...POSSIBLY SCATTERING OUT AS WELL. THE GUIDANCE SHOWS
QUITE A BIT OF DRYING ACROSS THE CWFA TODAY AS PW VALUES FALL THRU
THE DAY. HOWEVER...LOW LEVEL MOISTURE REMAINS HIGH AND MODERATE
INSTABILITY SHUD DEVELOP ONCE AGAIN. BEST INSTABILITY WILL BE EAST
AND SOUTH OF THE MTNS THIS AFTERNOON. MODERATE SHEAR DEVELOPS AS
ANOTHER SHORT WAVE MOVES INTO THE AREA. DECENT FORCING SHUD DEVELOP
EAST AND SOUTH OF THE MTNS WITH THE SHORT WAVE AND UPPER DIVERGENCE
MOVING IN. THEREFORE...EXPECT BEST COVERAGE EAST AND SOUTH OF THE
MTNS THIS AFTERNOON AND EARLY EVENING. SREF MEAN DCAPE VALUES ARE
OVER 500 J/KG THIS AFTERNOON...BUT MINIMAL CHC OF VALUES ABOVE 1000
J/KG. NAM IS FORECASTING QUITE A BIT OF SFC DELTA THETA-E AS WELL.
THEREFORE...SPC HAS MOST OF THE CWFA IN A MARGINAL RISK WITH
DAMAGING WINDS THE MAIN THREAT. EXPECT COVERAGE TO DIMINISH TO
ISOLATED OVERNIGHT WITH LOSS OF HEATING AND FORCING. HIGHS WILL BE
NEAR TO A LITTLE ABOVE NORMAL WITH LOWS AROUND 5 DEGREES ABOVE
NORMAL.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 230 AM WEDNESDAY...A SHORTWAVE TROF WILL CROSS THE GREAT LAKES
ON THURSDAY...WITH SOME TRAILING VORTICITY SHEARING OUT ACRS THE
CENTRAL/SOUTHERN APPALACHIANS. AT THE SFC...A WEAK FRONT PUSHES ACRS
THE OHIO VALLEY...BUT WASHES OUT AT THE APPALACHIANS. THE FLOW
AROUND THE HIGH OFF THE EAST COAST AND AHEAD OF THE FRONT...RESULTS
IN CONFLUENT FLOW THAT ALLOWS FOR PWATS TO RETURN TO THE 1.5 TO 1.75
INCH RANGE ACRS THE CWFA. GUIDANCE SHOWS SCATTERED TO NUMEROUS SHWRS
AND TSTMS THURSDAY AFTN...HIGHEST COVERAGE IN THE MTNS. FCST SNDGS
SHOW VERY WEAK DEEP LAYER FLOW...WITH 10 KTS OR LESS UP TO ABOUT 20
KFT. WHILE THE PROFILES ARE MOISTER THAN ON WEDNESDAY...THERE IS
STILL A LITTLE MID LVL DRY AIR...SO A FEW WET MICROBURSTS MAY BE
POSSIBLE. OTHERWISE...LOCALLY HEAVY RAIN WILL BE THE MAIN
THREAT...WITH SLOW STORM MOTION. CONVECTION SHUD WANE THURSDAY
EVENING. HIGH TEMPS WILL BE NEAR NORMAL...AND LOWS ABOVE NORMAL
THURSDAY NIGHT.

ON FRIDAY...AN UPPER RIDGE BEGINS TO BUILD BACK IN ACRS THE
SOUTHEAST STATES...WITH A SFC RIDGE AXIS LINGERING FROM THE FL
PANHANDLE TO THE OUTER BANKS. GUIDANCE SEEMS TO BE IN GOOD AGREEMENT
ON ANOTHER ROUND OF AFTN/EVE SHWRS AND TSTMS ACRS THE MTNS AND
FOOTHILLS. HOWEVER...THE LOWER PIEDMONT MAY BE CAPPED BY THE
BUILDING UPPER RIDGE. SO WILL GO WITH SLIGHTLY LOWER POPS THAN
THURSDAY...WITH A TIGHTER GRADIENT FROM SLGT CHC IN THE SOUTHEAST TO
AROUND 60% ALONG THE TN BORDER. CONVECTION SHUD WANE AGAIN FRIDAY
EVENING. TEMPS WILL BE A CATEGORY ABOVE NORMAL DURING THE DAY...AND
SEVERAL CATEGORIES ABOVE NORMAL FRIDAY NIGHT.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 245 AM WEDNESDAY...MODELS IN GOOD AGREEMENT ON ANOTHER BROAD
SHALLOW UPPER TROF CROSSING THE GREAT LAKES...WITH THE UPPER RIDGE
WEAKENING SLIGHTLY ACRS THE SOUTHEAST STATES OVER THE WEEKEND. THIS
WILL ALLOW A SLOW-MOVING COLD FRONT TO PUSH SOUTHEAST ACRS THE OH/TN
VALLEYS SATURDAY AND SUNDAY...THEN STALL OUT ACRS THE SOUTHERN
APPALACHIANS FOR MONDAY AND TUESDAY.

SATURDAY LOOKS LIKE IT WILL HAVE THE LOWEST POPS OF THE
PERIOD...WITH JUST A LOW-END CHC IN THE MTNS...AND PROBABLY DRY ACRS
MOST OF THE PIEDMONT. POPS RAMP UP AGAIN SUNDAY AND MONDAY...AS THE
RIDGE WEAKENS AND THE FRONT PUSHES IN FROM THE NORTHWEST. SHEAR WILL
STAY FAIRLY WEAK...BUT THERE MAY BE A SMALL SEVERE THREAT. THE GFS
IS MORE BULLISH ON BRINGING MORE STABLE AIR IN ACRS THE NRN HALF OF
THE CWFA...AS A WEAK WEDGE DEVELOPS DUE TO A 1028-1030 MB SFC HIGH
PRES BUILDING IN ACRS THE NORTHEAST STATES. THE ECMWF IS STILL MUCH
WEAKER WITH THE HIGH...AND DOESN/T PUSH THE BACKDOOR FRONT INTO THE
AREA UNTIL TUESDAY. SO MORE UNCERTAINTY FOR EARLY NEXT WEEK...BUT
WILL FEATURE ABOVE CLIMO POPS EACH DAY SUN-TUE...WITH HIGHEST POPS
ON MONDAY. TEMPS WILL BE THEIR WARMEST SAT-SUN AHEAD OF THE
FRONT...THEN BACK TO NEAR OR SLIGHTLY ABOVE NORMAL MON-TUE. MIN
TEMPS WILL REMAIN WELL ABOVE NORMAL EACH NIGHT WITHIN THE SUMMERY
AIR MASS.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...AT LEAST TEMPO LIFR CIGS ARE EXPECTED TO CONTINUE THROUGH
ABOUT 14Z. A BRIEF VISBY RESTRICTION IS ALSO POSSIBLE...BUT HAVE
LIMITED REDUCED VISBY TO 6SM IN A TEMPO ATTM. WHATEVER FORMS...
IMPROVEMENT WILL BE SLOW WITH VFR POSSIBLY HOLDING OFF UNTIL 18Z.
EXPECT DIURNAL CONVECTION AGAIN TODAY...ALTHOUGH COVERAGE WILL BE
LESS. STILL HIGH ENUF FOR CONTINUED PROB30. EXPECT MVFR CIGS TO
REDEVELOP TOWARD DAYBREAK THU...BUT IFR POSSIBLE. S TO SW WINDS THRU
THE PERIOD.

ELSEWHERE...IFR CIGS WILL ONLY SLOWLY LIFT THRU THE DAY WITH VFR
CIGS POSSIBLY HOLDING OFF UNTIL 18Z. MEANWHILE...RECENTLY DEVELOPED
LIFR FOG AT KAVL WILL BURN OFF MUCH MORE QUICKLY. DIURNAL CONVECTION
EXPECTED AGAIN...ALTHOUGH COVERAGE WILL BE LESS. STILL NEED TO
RETAIN PROB30. MVFR AND POSSIBLY IFR CIGS DEVELOP AGAIN TOWARD
DAYBREAK THU. S TO SW WINDS THRU THE PERIOD. KAVL THE EXCEPTION
WHERE NLY WIND THIS MORNING BECOME SLY FOR THE AFTERNOON.

OUTLOOK...MOIST SW FLOW WILL CONTINUE TO AFFECT THE TERMINAL
FORECAST AREA RIGHT THROUGH THE UPCOMING WEEKEND...AS A COLD FRONT
LAYS OVER TO THE NORTH OF THE AREA. EXPECT MORNING STRATUS TO RESULT
EACH DAY...WITH CONTINUED BETTER THAN CLIMATOLOGICAL CHANCES OF
AFTN/EVENING SHRA/TSRA EACH DAY.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       MED   77%     HIGH 100%     HIGH 100%     MED   79%
KGSP       HIGH  81%     HIGH 100%     HIGH 100%     HIGH  81%
KAVL       HIGH  82%     HIGH 100%     HIGH 100%     MED   70%
KHKY       HIGH  92%     HIGH 100%     HIGH 100%     HIGH  91%
KGMU       MED   77%     HIGH 100%     HIGH 100%     HIGH  85%
KAND       HIGH  83%     HIGH 100%     HIGH 100%     LOW   58%

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...ARK
NEAR TERM...JDL/RWH
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...JDL/RWH


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