Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 270727
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
327 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 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 /08Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...SHRA HAVE DISSIPATED AND SHUD NOT RETURN THIS MORNING.
HOWEVER...A FEW LIGHT SHRA OR SPRINKLES ARE POSSIBLE. GUIDANCE STILL
SUGGESTS MVFR THEN IFR CIGS DEVELOPING BY DAYBREAK AS IS OCCURRING
TO THE WEST. HAVE GONE WITH THESE TRENDS AS WELL. EXPECT A RETURN TO
MVFR BY MID MORNING...THEN LOW VFR BY NOON. AFTERNOON TSRA EXPECTED
AGAIN...AND HAVE INCLUDED PROB30 DURING THIS TIME. S TO SW WINDS
THRU THE PERIOD.

ELSEWHERE...IFR ALREADY DEVELOPED ACROSS THE SC SITES...BUT HAS BEEN
IN AND OUT THE LAST FEW HOURS. EXPECT IFR TO BE THE PREDOMINANT
FLIGHT CATEGORY THIS MORNING...SO HAVE STARTED IFR BUT KEPT TEMPO
VFR EARLY FOR THE BRIEF SCATTERING. KAVL AND KHKY SHUD SEE MVFR THEN
IFR BEFORE DAYBREAK. SHUD SEE A SLOW RISE TO LOW VFR AFTER DAYBREAK.
DIURNAL CONVECTION EXPECTED AGAIN...SO HAVE INCLUDED PROB30. HAVE
KEPT LOW VFR FOR THE EVENING...BUT RESTRICTIONS COULD RETURN BEFORE
THE END OF THE PERIOD. S TO SW WINDS THRU THE PERIOD.

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...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       HIGH  86%     HIGH  81%     HIGH 100%     HIGH 100%
KGSP       LOW   48%     MED   78%     HIGH 100%     HIGH 100%
KAVL       MED   69%     HIGH  86%     HIGH 100%     HIGH 100%
KHKY       MED   76%     MED   72%     HIGH 100%     HIGH 100%
KGMU       LOW   48%     HIGH  88%     HIGH 100%     HIGH 100%
KAND       LOW   47%     LOW   59%     HIGH 100%     HIGH  82%

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...RWH
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...RWH


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