Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 171928
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
328 PM EDT WED SEP 17 2014

.SYNOPSIS...
A COOL RIDGE OF HIGH PRESSURE WILL SLOWLY BUILD SOUTHWEST ACROSS THE
AREA THROUGH TONIGHT...THEN INTENSIFY ON FRIDAY. THIS PATTERN IS
EXPECTED TO PERSIST THROUGH THE WEEKEND...BEFORE A COLD FRONT
CROSSES THE AREA EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 235 PM EDT...VISIBLE SATELLITE IMAGERY THIS AFTERNOON IS
SHOWING STEADY EROSION OF THE LOW CLOUD LAYER IN THE WEAK CAD REGION
N OF THE RECENTLY DEPARTED BACKDOOR FRONT. THIS SHOULD CONTINUE AS
VAD WIND PROFILES INDICATE LITTLE RESIDUAL UPGLIDE OVER THE CAD.
HOWEVER...BOUNDARY LAYER MOISTURE IS ALLOWING SOME CUMULUS
REDEVELOPMENT AS SCATTERING OCCURS...AND WEAK PASSING H5 SHORTWAVES
ALOFT COULD TRIGGER SOME ISOLD SHALLOW CONVECTION ALONG THE MOST
UNSTABLE SRN/ERN MTNS AND SE PIEDMONT THROUGH EARLY EVENING. THE
BEST FOCUS OF ANY UPPER FORCING SHOULD BE WITH A 60 TO 70 KT UPPER
JETLET CROSSING THE REGION IN WNW FLOW ALOFT...PLACING THE BEST
UPPER DIVERGENCE OVER THE MIDLANDS AND PIEDMONT EAST OF OUR FORECAST
AREA TOWARD EVENING. OTHERWISE...ANTICIPATE MOSTLY DRY CONDITIONS
WITH LOW CLOUDS AND PATCHY FOG FILLING BACK IN ACROSS THE REGION
OVERNIGHT AS SFC WINDS SLACKEN.

A TRAIN OF ADDITIONAL WEAK SHORTWAVES WILL CONTINUE TO PUSH INTO THE
ERN TROUGH ON THU...BUT AGAIN WITH WEAK TRIGGERING AND LIMITED
MOISTURE. WILL FEATURE LOW END ISOLD POPS FOR THU AFTN AS 850 TO 500
MB LAPSE RATES REMAIN REASONABLY STEEP AT 6.5 DEG C/KM. LOW CLOUDS
SHOULD SCATTER A BIT MORE QUICKLY THU...RESULTING IN MAX TEMPS A
DEGREE OR TWO WARMER IN MOST AREAS...BUT STILL A LITTLE BELOW CLIMO.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 245 PM EDT WEDNESDAY...THE SHORT TERM FORECAST PERIOD
INITIALIZES THURSDAY EVENING AMIDST POSSIBLE ONGOING
SHOWER/THUNDERSTORM ACTIVITY WITH POPS STARTING OUT AT SLIGHT CHANCE
LEVELS ALONG THE BLUE RIDGE WITH THE REMAINDER OF THE FORECAST AREA
BEING DRY. POPS WILL TAPER OVERNIGHT...WITH AN INCREASING POP TREND
INTO THE AFTERNOON HOURS ON FRIDAY AS HIGH PRESSURE BEGINS TO WEDGE
FURTHER SOUTH LEADING TO INCREASING UPGLIDE POTENTIAL.
THUS...FORECAST WILL FEATURE REGIONWIDE SLIGHT CHANCE POPS FOR
FRIDAY AFTERNOON BEFORE TAPERING FOR THE OVERNIGHT AS THE WEDGE
EXTENDS FURTHER SOUTH ALONG WITH BEST UPGLIDE POTENTIAL.  FORECAST
WILL REMAIN DRY THROUGH SATURDAY AS HIGH PRESSURE CONTINUES TO
STRENGTHEN WITH COOLER NORTHERLY FLOW PREVAILING.  MEANWHILE...THE
NEXT UPPER TROF WILL BE DIGGING ACROSS THE UPPER MIDWEST WITH A COLD
FRONT DRAPED SOUTHWARD ALONG THE MISSISSIPPI RIVER VALLEY.
TEMPERATURES THROUGH THE SHORT TERM WILL REMAIN SEASONABLY COOLER
LEADING TO BELOW NORMAL LEVELS EACH AFTERNOON.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 310 PM EDT WEDNESDAY...NO SIGNIFICANT CHANGES FOR THE EXTENDED
RANGE PORTION OF THE FORECAST WHICH INITIALIZES SATURDAY EVENING
AMIDST DEEP SURFACE WEDGE AND PREVAILING NORTHERLY FLOW.  FORECAST
WILL REMAIN DRY THROUGH THE OVERNIGHT INTO SUNDAY AFTERNOON BEFORE
GRADUALLY RAMPING UP TO SLIGHT CHANCE LEVELS ACROSS THE WESTERN
ZONES OF THE FORECAST AREA WHERE PREFRONTAL/UPSLOPE SHOWER ACTIVITY
WILL REMAIN A POSSIBILITY.  POPS WILL INCREASE ON MONDAY AS UPPER
TROF AND ASSOCIATED COLD FRONT SWING THROUGH THE SOUTHERN/CENTRAL
APPS.  FORECAST WILL FEATURE CHANCE LEVEL POPS ACROSS THE MOUNTAINS
ALONG AND JUST AHEAD OF THE FRONTAL INTRUSION MONDAY AFTERNOON WITH
ONLY SLIGHT CHANCE POPS HIGHLIGHTED FURTHER EAST.  CONSIDERING
RETURNING SOUTHERLY FLOW ON SUNDAY AS ABOVE MENTIONED WEDGE
RETREATS...ALONG WITH IMPROVED SHEAR ASSOCIATED WITH APPROACHING
UPPER TROF AXIS...DID GO AHEAD AN INCLUDE SLIGHT CHANCE THUNDER
MENTION ON MONDAY AFTERNOON.  BEYOND THAT...A DRY FORECAST WILL
PREVAIL FOR THE REST OF THE EXTENDED RANGE AS ANOTHER HIGH PRESSURE
RIDGE SLIDES BY TO THE NORTH AND EXTENDS SOUTHWARD IN YET ANOTHER
WEDGE CONFIGURATION.  SEASONABLE COOLER TEMPERATURES WILL PREVAIL
THROUGH THE PERIOD.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
AT KCLT...VISIBLE IMAGERY SHOWS SLIGHT SCATTERING AND IMPROVEMENT OF
THE LOW CEILINGS FROM THE EAST AT ISSUANCE TIME. ANTICIPATE FAIRLY
SOLID MVFR RESTRICTIONS THROUGH THE LATE AFTN HOURS...WITH ANY
RECOVERY TO VFR LIKELY VERY BRIEF THIS EVENING BEFORE MVFR CIGS
RETURN QUICKLY IN THE ABUNDANT BOUNDARY LAYER MOISTURE OVERNIGHT.
THERE IS DEVELOPING CONSENSUS THAT A ROUND OF VLIFR TO LIFR
RESTRICTIONS MAY RETURN BY 09Z. WILL TREND THE TAF TOWARD LOWER END
IFR FOR NOW. RECOVERY THROUGH MVFR WILL TAKE THE BETTER PART OF THU
MORNING. ALTHOUGH WEAK SHORTWAVES WILL MOVE OVERHEAD...TIMING IS TOO
UNCERTAIN TO FEATURE ANY PRECIPITATION IN THE TAF AT PRESENT. EXPECT
LIGHT NE SFC WINDS THROUGHOUT.

ELSEWHERE...SLOW BUT STEADY IMPROVEMENTS IN MVFR CIGS ARE EXPECTED
AT THE MTN AND FOOTHILL TAF SITES THROUGH LATE AFTERNOON. A BRIEF
PERIOD OF VFR IS EXPECTED...BUT THIS SHOULD BE FAIRLY SHORT LIVED AS
CIGS RETURN QUICKLY TO MVFR OVERNIGHT GIVEN THE ABUNDANT BOUNDARY
LAYER MOISTURE. ISOLD SHRA CANNOT BE RULED OUT AT KAVL AND THE
UPSTATE TAFS THIS EVENING WITH PASSING SHORTWAVES OVERHEAD...BUT THE
FORCING IS TOO WEAK AND UNCERTAIN TO TIME. EXPECT A PERIOD OF IFR TO
LIFR RESTRICTIONS TO DEVELOP THROUGH DAYBREAK AS THE SFC WINDS
SLACKEN IN THE WEAK CAD REGIME. SLOW BUT STEADY LIFTING FROM IFR
THROUGH MVFR IS EXPECTED THU MORNING. SFC WINDS WILL CONTINUE
NE...EXCEPT TURNING FROM SE TO NW AT KAVL THROUGH THE PERIOD.

OUTLOOK...THE POTENTIAL FOR LATE NIGHT/MORNING FOG/STRATUS WILL
PERSIST INTO THE EARLY PART OF THE WEEKEND...ESPECIALLY IN THE MTN
VALLEYS. CONDITIONS MAY FINALLY DRY OUT FOR THE LATTER PART OF THE
WEEKEND. A COLD FRONT MAY BRING INCREASING CHANCES FOR SHOWERS/TSTMS
EARLY NEXT WEEK.

CONFIDENCE TABLE...

            19-01Z        01-07Z        07-13Z        13-19Z
KCLT       HIGH  83%     MED   71%     MED   75%     MED   77%
KGSP       HIGH  85%     HIGH  87%     MED   74%     MED   75%
KAVL       HIGH  88%     HIGH  90%     HIGH  82%     MED   79%
KHKY       HIGH  89%     HIGH  92%     MED   77%     MED   71%
KGMU       HIGH  84%     HIGH  88%     MED   70%     MED   76%
KAND       HIGH  81%     HIGH  87%     MED   75%     HIGH  84%

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...HG
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...HG





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