Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS62 KGSP 172348
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
748 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 730 PM...A FEW SHOWERS HAVE MANAGED TO DEVELOP OVER THE SRN
MOUNTAINS AND UPPER SAVANNAH BASIN ON ACCOUNT OF INSTABILITY
AFFORDED BY SKY THAT CLEARED EARLY ENOUGH IN THE AFTERNOON AND SOME
WEAK LOW LEVEL CONVERGENCE. WILL EXTEND AND ENLARGE THE PRECIP
CHANCE AREA TO INCLUDE MORE OF NE GEORGIA AND THE WRN UPSTATE. THE
SHOWERS SHOULD DIMINISH BY 02Z OR SO. OTHERWISE...CLOUDS CONTINUE TO
DIMINISH...BUT THAT TREND SHOULD HALT WITH SUNSET AND THEN REVERSE
AS A WEAK UPSLOPE FLOW ACTS ON AVAILABLE LOW LEVEL MOISTURE TO BRING
THE LOW CLOUDS BACK.

PREVIOUS DISCUSSION...

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 /00Z THURSDAY THROUGH MONDAY/...
AT KCLT...VISIBLE IMAGERY SHOWS ONLY SCATTERED CLOUDS REMAINING
ACROSS THE PIEDMONT...SO VFR CONDITIONS SHOULD PREVAIL THROUGH LATE
EVENING WITH A LIGHT N WIND. THE LOW LEVEL FLOW SHOULD COME AROUND A
BIT MORE EASTERLY AFTER SUNSET...SO EXPECT THE LOW CLOUDS TO RETURN
AT SOME POINT DURING THE OVERNIGHT HOURS GIVEN THE AMOUNT OF LOW
LEVEL MOISTURE PRESENT. THE PREVIOUS PROGRESSION IN THE TAF STILL
LOOKS GOOD...WITH CLOUDS/VIS INITIALLY IN THE MVFR RANGE STARTING
AROUND 05Z...EARLIER THAN GUIDANCE...AND THEN EVENTUALLY LOWERING TO
IFR AROUND 08Z. NOT CONVINCED THAT WE WILL SEE LOW IFR AS UPSLOPE
DOES NOT LOOK ALL THAT GREAT...SO PREFER TO TREND MORE FAVORABLE AND
AMEND LATER. THE LOW CLOUDS WILL BE SLOW TO LIFT AND SCATTER AGAIN
ON THURSDAY...BUT IT LOOKS LIKE CONDITIONS WILL IMPROVE TO VFR MUCH
EARLIER THAN TODAY...AROUND 17Z...BUT STILL WITH A BKN CEILING. WIND
SHOULD STAY LIGHT NE.

ELSEWHERE...SIMILAR TO KCLT...A VFR BREAK THROUGH EVENING...WITH LOW
CLOUDS AND FOG RETURNING LATE EVENING OR EARLY THURSDAY MORNING. THE
MTNS...KAVL...HAVE THE BEST CHANCE OF SEEING IFR VIS RESTRICTIONS
AND THE GUIDANCE SHOWS A LONG PERIOD OF VLIFR. THE TAF REFLECTS MORE
OPTIMISTIC THINKING THAT SOME HIGH CLOUDS WILL PREVENT DENSE FOG.
ELSEWHERE...EXPECT WEAK UPSLOPE COMPONENT TO BRING CEILING/VIS DOWN
TO MVFR AND EVENTUALLY IFR BEFORE DAYBREAK. THE CLOUDS WILL BE SLOW
TO LIFT AND SCATTER AS ON WEDNESDAY.

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...

            23-05Z        05-11Z        11-17Z        17-23Z
KCLT       HIGH  83%     MED   69%     MED   71%     HIGH  90%
KGSP       HIGH 100%     MED   71%     LOW   57%     HIGH 100%
KAVL       HIGH  97%     MED   77%     MED   71%     HIGH  87%
KHKY       HIGH 100%     MED   79%     MED   64%     HIGH  80%
KGMU       HIGH 100%     MED   73%     LOW   57%     HIGH 100%
KAND       HIGH 100%     MED   67%     MED   66%     HIGH 100%

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/PM
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...PM





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.