Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 031500
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1100 AM EDT WED JUN 3 2015

.SYNOPSIS...
UPPER LEVEL LOW PRESSURE WILL GRADUALLY DRIFT ACROSS THE
SOUTHEASTERN STATES THROUGH THE REMAINDER OF THE WORK WEEK.
MEANWHILE A WEDGE OF COOL AIR WILL REMAIN ENTRENCHED OVER MOST OF
THE FORECAST AREA THROUGH THURSDAY. THE INTERACTION OF THESE
FEATURES WILL ENHANCE THE LIKELIHOOD OF SHOWERS AND
THUNDERSTORMS...AND KEEP TEMPERATURES A FEW DEGREES BELOW NORMAL.
THE PATTERN WILL SLOWLY TRANSITION TO MORE SEASONABLE WEATHER OVER
THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 AM...STRATUS HAS FILLED IN ACROSS THE AREA AS
EXPECTED...AS A SUMMER WEDGE STRENGTHENS ATOP THE CWFA. THIS MAKES
FOR A COMPLEX NEAR TERM FCST...AS GUIDANCE ALLOWS THE MTNS AND THE
SUOTHERN HALF OF THE PIEDMONT TO MIX OUT AND BECOME MODERATELY
UNSTABLE THIS AFTN. WITH AN UPPER LOW SPINNING OVER ERN TN...OUR
AREA CONTINUES TO BE UNDER DEEP-LAYER Q-VECTOR CONVERGENCE. HIGH-RES
MODELS SHOW CONVECTION FIRING AROUND PERIPHERY OF THE WEDGE AND ACRS
THE MTNS BY EARLY AFTN...WITH STEERING FLOW TAKING SOME OF THE
ACTIVITY INTO THE WEDGE OUT OF THE SOUTH. FLOW IS WEAKER TODAY
OVERALL...BUT THERE IS MORE DIRECTIONAL SHEAR GIVEN THE EASTERLY LOW
LEVEL FLOW AND SOUTHERLY MID LVL FLOW AROUND THE LOW. SO A MARGINAL
HAIL AND WIND THREAT WILL EXIST ACRS THE MTNS...NE GA AND THE
UPSTATE. THE NC FOOTHILLS AND PIEDMONT LOOK MORE STABLE...WITH
MAINLY LIGHT SHWRS AND DRIZZLE MUCH OF THE DAY. TEMPS ARE TRICKY AS
WELL...HAVE BLENDED IN THE THE CONSRAW TEMPS WHICH ARE COOLER THAN
THE PREVIOUS FCST...ESP ACRS THE NORTHERN ZONES WHERE CLOUDS WILL BE
THICKEST AND MOST PERSISTENT.

TONIGHT...THE CENTER OF THE H5 LOW WILL REMAIN OVER THE FORECAST
AREA...BUT SHOULD CONTINUE TO DRIFT EAST. AT THE SFC...A RIDGE OF
HIGH PRESSURE IS EXPECTED TO RIDGE SW ACROSS THE WESTERN CAROLINAS.
LOW LEVEL MOISTURE AND NE WINDS WILL INCREASE ACROSS THE CWA
OVERNIGHT. WEAK INSTABILITY MAY REMAIN OVER THE LAKELANDS...BUT NEAR
ZERO TO THE NORTH. WEAK ISENTROPIC LIFT AROUND 300 K SHOULD SUPPORT
A FEW SHRA OR PATCHES OF DZ TONIGHT...I WILL HIGHLIGHT WITH CHC
POPS. LOW TEMPS MAY RANGE FROM THE U50S ACROSS THE MTNS TO LOW TO
MID 60S EAST.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 230 AM WED...MODELS HAVE TRENDED LATER WITH THE EROSION OF THE
WEDGE...WHICH SEEMS REASONABLE. THEY NOW FEATURE MORE INTERACTION OF
THE SLOW MOVING UPPER LOW AND THE WEDGE BOUNDARY. GFS GOES SO FAR AS
TO CLOSE OFF A SFC LOW OFF THE OUTER BANKS FRIDAY MORNING. CONSENSUS
IS TO MAINTAIN EASTERLY FLOW THRU THURSDAY DESPITE THE PARENT HIGH
PRESSURE MOVING OFF THE NORTHEAST COAST. UPSLOPE INTO THE BLUE RIDGE
WILL CONTINUE TO PRODUCE ABOVE CLIMO POPS...PARTICULARLY ALONG THE
RIDGE ITSELF. VORTICITY PROGS SUGGEST THE LOW WILL BE A BIT TOO FAR
EAST TO PROVIDE MUCH EXTRA LIFT ON ITS OWN...BUT SHOULD CONTINUE TO
ENHANCE LAPSE RATES AROUND THE WEDGE BOUNDARY. THUNDER WILL BE
ADVERTISED ON ITS WARM SIDE. MAX TEMPS WILL STAY A COUPLE CATEGORIES
BELOW NORMAL. MINS FRIDAY MRNG WILL BE NEAR NORMAL.

A DEEP NRN STREAM TROUGH MOVING THRU ERN CANADA WILL BRING A COLD
FRONT TO THE GREAT LAKES AND ST LAWRENCE VALLEY EARLY SATURDAY. THE
TROUGH SEEMS TO PHASE WITH THE UPPER LOW OVER OUR REGION AND HELP
SUSTAIN IT. MEANWHILE A SHORTWAVE WILL ROUND THE SHARP SRN PLAINS
RIDGE AND INTO THE OHIO VALLEY. PAST RUNS HAVE SUGGESTED THIS TOO MAY
MERGE WITH THE TROUGH OR AT LEAST MINIMIZE HEIGHT RISES IN ITS WAKE.
LOW LEVEL FLOW CONTINUES TO REFLECT WEAK OFFSHORE LOW
PRESSURE...FAVORING NORTHERLY. WITHOUT GOOD DOWNSLOPING WINDS TO
SCOUR IT...THE WEDGE COULD HANG ON THRU FRIDAY. A SMALL AREA OF HIGH
PRESSURE IS ANALYZED ON NAM/GFS PROGS OVER THE MID-ATLANTIC WITH A
WEDGELIKE MSLP PATTERN. PROFILES ARE LESS UNSTABLE BUT SUFFICIENT FOR
SLIGHTLY ELEVATED POPS COMPARED TO CLIMO. TEMPS SHOULD REBOUND TO A
COUPLE DEGREES BELOW NORMAL FRI AFTN...WITH LOWS A BIT ABOVE NORMAL
SAT MRNG.

A RETURN OF WEAK SHEAR IMPLIES SLOW MOVING STORMS MAY ENHANCE HYDRO
CONCERNS. MOISTURE IS NOT EXCEPTIONALLY HIGH FRI OR SAT BUT PWAT
VALUES ARE HIGHER THAN THEY WERE TUESDAY...WHEN ISOLATED FLOOD ISSUES
SPRANG UP. SO THE SITUATION WILL LIKELY STILL REQUIRE CAREFUL
MONITORING...PARTICULARLY IF THE WEDGE BOUNDARY IS ABLE TO FOCUS
CONVECTION THU AFTN.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 300 AM WED...ANOTHER DOME OF CANADIAN HIGH PRESSURE WILL PUSH
SEWD INTO THE NERN CONUS THRU SUNDAY. THE UPPER PATTERN DOES NOT
APPEAR FAVORABLE FOR IT TO LOCK IN AS CAD...BUT EASTERLY FLOW WILL BE
MAINTAINED INTO THE CWFA SAT AND MOST OF SUN. WILL MAINTAIN ABOVE
CLIMO POPS NEAR THE BLUE RIDGE. MAX TEMPS WILL REBOUND TO JUST BELOW
NORMAL. A LOW PRESSURE SYSTEM WILL FOLLOW THE HIGH...THE SFC LOW
MOVING OVER ONTARIO SUNDAY NIGHT. 03/00Z GFS AND 02/12Z EC DIFFER IN
THEIR DEPICTIONS OF THIS SYSTEM...THE LATTER BEING STRONGER AND
FURTHER SOUTH WITH IT. BOTH MODELS EFFECT A RETURN OF SOUTHERLY FLOW
FOR OUR AREA MONDAY...AND ABOVE NORMAL MAX TEMPS...PRIOR TO THE
ARRIVAL OF THE WEAK COLD FRONT FROM THE ONTARIO SYSTEM. A BROAD AND
SOMEWHAT DEEP TROUGH DIGS INTO THE ERN STATES THEREAFTER...WHILE THE
COLD FRONT STALLS JUST SOUTH OF THE CWFA POTENTIALLY PROLONGING
UNSETTLED WEATHER. GFS FEATURES A SECOND...MORE POTENT COLD FRONT AS
THE AXIS OF THIS TROUGH REACHES THE SRN APPALACHIANS TUE NIGHT. THE
EC HAS BEEN DRIER...AND WHILE THE NEW 03/00Z RUN MAINTAINS THE
OVERALL TRENDS OF THE PREVIOUS RUN...IT HAS NOW COME IN WITH LESS
PRECIP EARLY NEXT WEEK. NONETHELESS ON ACCOUNT OF THE PATTERN CHANCE
POPS WILL BE MAINTAINED MON-TUE.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
KCLT...LATEST SFC ANALYSIS INDICATED A STATIONARY FRONT EAST OF
I-85 WITH A FRONTAL WAVE ACROSS CENTRAL GA. RADAR IMAGES SHOW SEVERAL
LARGE CLUSTERS OF SHRA/TSRA GENERALLY ALONG AND EAST OF THE SFC
BOUNDARY. WEST AND NORTH OF THE FRONT...LIGHT WINDS HAVE VEERED FROM
THE NNE. BASED ON THE SFC PATTERN AND RECENT OBSERVATIONS...IT
APPEARS THAT WEAK CAD HAS SETTLED OVER PORTIONS OF THE NC FOOTHILLS
AND PIEDMONT. IFR CEILINGS WILL BEGIN THE 12Z TAF...TEMPO RISING TO
MVFR THROUGH 14Z. BASED ON THE LATEST MOS AND NAM FORECAST
SOUNDINGS...IFR CLOUDS MAY LINGER INTO THE LATE MORNING...THEN
REMAINING MVFR THROUGH THE REST OF THE DAY. WINDS WILL REMAIN
GENERALLY FROM THE NE THROUGH THE TAF PERIOD...SPEEDS SHOULD PEAK IN
THE LOW TEENS THIS AFTERNOON. IT APPEARS THAT THE APPROACH OF THE
CLOSED H5 LOW THIS AFTERNOON WILL TRIGGER SHRA AND POSSIBLY A TSRA
THROUGH EARLY EVENING. I WILL INDICATE IN THE TAF -SHRA THROUGH THIS
AFTERNOON...WITH A PROB30 FOR TSRA FROM 21Z TO 1Z. BASED ON
MESOSCALE MODELS...CAD SHOULD SURGE SOUTHWARD AFTER SUNSET...I WILL
TIME THE RETURN OF IFR CEILINGS AT 3Z.

ELSEWHERE...AT 12Z...CONDITIONS ACROSS THE WESTERN CAROLINAS RANGED
FROM VFR TO VLIFR. BETWEEN 12Z-14Z...BKN STRATUS SHOULD DEVELOP
ACROSS THE TERMINALS...EVEN AREAS THAT OBSERVE VFR CONDITIONS AT
10Z. THE STRATUS SHOULD LINGER UNTIL MID DAY ACROSS THE UPSTATE AND
MTNS...BUT SHOULD REMAIN THROUGH THE DAY FOR KHKY. I WILL FEATURE
-SHRA FOR MOST SITES DURING THE AFTERNOON HOURS...ALL SITES A PROB30
GROUP FOR LATE THIS AFTERNOON AND EARLY EVENING FOR -TSRA. AFTER
SUNSET...CAD IS EXPECTED TO SURGE SOUTHWARD AND RESTRICTIVE CEILING
WILL BECOME WIDESPREAD.

OUTLOOK...A MID LEVEL LOW WILL LINGER OVER THE AREA THRU AT LEAST
THURSDAY...WITH DEEP MOISTURE. SO NUMEROUS SHOWERS AND THUNDERSTORMS
ARE EXPECTED EACH AFTERNOON AND EVENING. MORNING STRATUS AND FOG
WILL ALSO REMAIN A POSSIBILITY...ESPECIALLY OVER WET GROUND...THRU
AT LEAST FRIDAY.

CONFIDENCE TABLE...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       MED   68%     MED   66%     LOW   59%     MED   71%
KGSP       HIGH  94%     MED   79%     MED   76%     HIGH  87%
KAVL       MED   77%     HIGH  89%     MED   77%     MED   70%
KHKY       MED   74%     HIGH  90%     LOW   52%     HIGH  82%
KGMU       HIGH  94%     HIGH  85%     MED   74%     HIGH  92%
KAND       HIGH  90%     HIGH 100%     MED   63%     HIGH  87%

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...WIMBERLEY
NEAR TERM...ARK/NED
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...NED



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