Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 310713
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
313 AM EDT SUN MAY 31 2015

.SYNOPSIS...
BERMUDA HIGH PRESSURE WILL PERSIST ACROSS THE REGION INTO EARLY NEXT
WEEK...WITH MOIST SOUTHERLY FLOW SUPPORTING SCATTERED AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS. A COLD FRONT APPROACHES THE AREA
ON TUESDAY AND IS EXPECTED TO BECOME STATIONARY THROUGH THE MIDDLE
OF NEXT WEEK WITH CONTINUED CHANCES FOR CONVECTION EACH DAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 245 AM...RADAR AND SATELLITE IMAGES INDICATE THAT AN OLD SEA
BREEZE BOUNDARY LIFT NW ACROSS THE PIEDMONT AND FOOTHILLS...BECOMING
NEARLY STATIONARY ALONG THE EAST FACING SLOPES OF THE MTNS. BKN TO
OVC STRATUS IS FORECAST TO DEVELOP ACROSS THE FORECAST AREA AROUND
DAYBREAK...REMAINING UNTIL MID MORNING. BY MID DAY...DIURNAL MIXING
SHOULD DISSIPATE THE STRATUS AND SCT TO BKN CU SHOULD DEVELOP. USING
A BLEND OF PREFERRED MOS...HIGH TEMPERATURES ARE FORECAST TO RANGE
WITHIN A DEGREE OR TWO OF VALUES OBSERVED ON SATURDAY.
HOWEVER...PERSISTENT RETURN FLOW IS EXPECTED TO YIELD AFTERNOON
DEWPOINTS 2 TO 4 DEGREES WARMER THAN SATURDAY. AT THE MID
LEVELS...HEIGHTS WILL GRADUALLY FALL ACROSS THE WESTERN ZONES AS A
CLOSED LOW DEVELOPS OVER ARKANSAS. FORECAST SOUNDINGS INDICATE THAT
WEAK TO MODERATE VALUES OF CAPE WILL EXIST ACROSS THE FORECAST AREA
THIS AFTERNOON. HOWEVER...FORECAST SOUNDINGS ALSO SHOW A SIGNIFICANT
LAYER OF CIN CENTERED AROUND H85. CAMS AND NEAR TERM MODELS INDICATE
THAT THE GREATEST COVERAGE OF SHOWERS AND THUNDERSTORMS SHOULD OCCUR
WITHIN A MOISTURE CONVERGENCE AREA ALONG THE TN/NC STATE LINE DURING
THE LATE AFTERNOON. TO THE EAST...GUIDANCE DOES NOT SHOW MUCH
COVERAGE...LIKELY THE HIGHEST OVER THE UPPER SAVANNAH RIVER VALLEY
AROUND SUNSET. I WILL CONTINUE TO INDICATE CHC POPS EAST WITH LIKELY
POPS ACROSS THE TN BORDER.

TONIGHT...CONVECTION COVERAGE MAY LINGER WELL INTO THE
NIGHT...SUPPORTED BY THE APPROACH OF A COLD FRONT AND SOUTH LLVL
WINDS. IN ADDITION...THE H5 TROF/CLOSED LOW CENTERED OVER THE
MISSISSIPPI RIVER DEEPENS DURING THE NIGHT. THE COMBINATION OF LOW
PRESSURE TO THE WEST AND HIGH PRESSURE OVER THE ATLANTIC...THE
ENVIRONMENT SHOULD REMAIN VERY MOIST OVERNIGHT. THE FORECAST WILL
FEATURE BKN TO OVC CLOUD COVER. LOW TEMPERATURES WILL RANGE FROM THE
LOW 60S WITHIN THE MTN VALLEYS TO MID TO UPPER 60S EAST.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 215 AM SUNDAY MORNING...THE SHORT TERM FCST PICKS UP AT 12Z ON
MONDAY WITH UPPER RIDGING LINGERING OVER THE REGION AND AN UPPER
TROF GRADUALLY MAKING ITS WAY TOWARDS THE CWFA. IT APPEARS THAT THE
MODELS HAVE SLOWED THE TROFS PROGRESSION EVEN MORE OVER THE PAST DAY
OR SO. THEY DEPICT A CLOSED H5 LOW DEVELOPING BY EARLY TUES WITH THE
LOW THEN STALLING OUT JUST TO OUR WSW ON WED. IT APPEARS THAT THE
LOW WILL REMAIN COMPLETELY SEPARATED FROM THE MEAN UPPER FLOW TO THE
NORTH WELL INTO THE MEDIUM RANGE.

AT THE SFC...MOIST SLY FLOW WILL OVERSPREAD MOST OF THE CWFA BY MON
MORNING. AS WE MOVE THRU MON...WIDESPREAD SHOWERS AND TS REMAIN
LIKELY WITH SLY FLOW TO OUR SOUTH AND NLY FLOW ASSOCIATED WITH THE
GREAT LAKES HIGH TO OUR NORTH. ITS APPEARS THAT WE WILL REMAIN
SANDWICHED IN BETWEEN THE NLY AND SLY FLOW THRU THE REMAINDER OF THE
PERIOD AS THE GREAT LAKES HIGH SLIDES FARTHER EAST. ANY DEGREE OF
WEDGING ASSOCIATED WITH THE HIGH WONT LIKELY DEVELOP UNTIL BEYOND
WED. AS FOR THE SENSIBLE FCST...NO SIG CHANGES WERE NEEDED FOR THE
PERIOD WITH WIDESPREAD LIKELY POPS FOR MON AFTERNOON/EARLY EVENING
HOURS. POPS REMAIN AT HIGH END CHANCE THRU 12Z WED WITH LINGERING
DEEP MOISTURE OVER THE AREA. MODEL PROFILES CONTINUE TO FEATURE HEALTHY
AMOUNTS OF SFC BASED CAPE EACH DAY WITH SPC INCLUDING OUR CWFA UNDER
A SLIGHT RISK AREA ON MON AND TUES. SUFFICE TO SAY...CONDITIONS
LOOK FAVORABLE FOR WIDESPREAD TS ACTIVITY WITH SOME STORMS BECOMING
SEVERE. TEMPS WILL HAVE A REDUCED DIURNAL RANGE DUE TO SIG CLOUD
COVER AND MOISTURE...WITH MAXES NEAR NORMAL AND MINS A FEW DEGREES
ABOVE NORMAL.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 245 AM SUNDAY MORNING...THE MEDIUM RANGE FCST PICKS UP AT 12Z ON
WEDNESDAY WITH AN H5 CUTOFF LOW DEVELOPING TO OUR WSW AND BROAD
UPPER RIDGING NORTH OF THE LOW. OVER THE REMAINDER OF THE
PERIOD...THE LONG RANGE MODELS NOW INDICATE THAT THE CUTOFF LOW WILL
REMAIN MOSTLY INTACT AND SLOWLY DRIFT SOUTHWARD TOWARDS THE GULF OF
MEX. AT THE SAME TIME...UPPER RIDGING BUILDS BACK OVER MUCH OF THE
EASTERN CONUS AND REMAINS THRU DAY 7.

AT THE SFC...A LARGE PLUME OF PERSISTENT DEEP LYR MOISTURE
ASSOCIATED WITH A DISSIPATING FRONTAL ZONE WILL KEEP THE FCST AREA
UNDER FAVORABLE CONDITIONS FOR WIDESPREAD SHOWERS AND TS FOR MOST OF
THE PERIOD. ON THURS...THE HIGH TRIES TO SET UP WEDGE TYPE SFC
PATTERN OVER THE FCST AREA BUT ITS NOT LOOKING VERY COHERENT
COMPARED TO PREVIOUS MODEL RUNS. TOWARDS THE END OF THE PERIOD ON
SAT...ANOTHER CANADIAN SFC HIGH MOVES SE TOWARDS NEW ENGLAND AND
COULD BRING US ANOTHER ROUND OF NELY FLOW...HOWEVER ITS STILL TOO
EARLY TO SAY WITH MUCH CERTAINTY. DIURNALLY DRIVEN POPS REMAIN IN
THE 20 TO 40% RANGE EACH DAY/EVENING. HIGH TEMPS WILL WARM STEADILY
THRU THE PERIOD WITH VALUES ENDING JUST ABOVE CLIMO FOR THE WEEKEND.
LOWS SHOULD REMAIN NEARLY CONSTANT WITH VALUES JUST ABOVE CLIMO EACH
DAY.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...AS OF 5Z...THE 0Z GUIDANCE HAS GENERALLY
INDICATED TOO MUCH CONVECTION ACROSS THE WESTERN CAROLINAS EARLY
THIS MORNING. THIS WILL MAKE THE GUIDANCE LESS USEFUL IN DETERMINING
THE EXTENT OF THE LOW CLOUDS AND FOG TOWARD SUNRISE. OTHERWISE...THE
GUIDANCE DID HAVE A GOOD HANDLE WITH THE PASSAGE OF A BOUNDARY
ASSOCIATED WITH AN OLD SEABREEZE. THIS BOUNDARY PASS ACROSS THE GSP
AREA AROUND 4Z BASED RADAR AND SATELLITE IMAGES. GIVEN THAT MOST
TERMINALS WILL BE ON THE MOIST SIDE OF THE BOUNDARY BY SUNRISE...IT
APPEARS THAT STRATUS WILL BE THE MOST LIKELY OUTCOME EARLY THIS
MORNING. I WILL INDICATE THAT MVFR STRATUS WILL DEVELOP DURING THE
PRE DAWN HOURS AND WILL LINGER UNTIL MID MORNING. KAND MAY FAVOR
CLOUD BASES LOWERING TO IFR BETWEEN 10Z TO 14Z. BY LATE
MORNING...ALL TERMINALS SHOULD OBSERVE VFR SCT CU WITH STEADY SOUTH
WINDS.

LATE THIS AFTERNOON...MODELS INDICATE THAT MODERATE CAPE SHOULD
DEVELOP ACROSS THE WESTERN CAROLINAS...WITH FALLING MID LEVEL
HEIGHTS. HOWEVER...THE FORECAST SOUNDINGS FROM THE NAM INDICATE A
50-90 J/KG LAYER OF CIN REMAINING THROUGH THE AFTERNOON. I WILL
FORECAST THE GREATEST COVERAGE ACROSS THE MTNS...BUT SCT SHRA/TSRA
SHOULD DEVELOP EAST OF THE MTNS DURING THE LATE AFTERNOON AND
EVENING. I WILL HIGHLIGHT THE CONVECTION WITH A PROB30 FOR EACH
TERMINAL LATE THIS AFTERNOON.

OUTLOOK...THE PATTERN IS EXPECTED TO BECOME MORE UNSETTLED/ACTIVE
INTO AT LEAST MID-WEEK...AS A COLD FRONT STALLS OVER THE REGION.
EXPECT AT LEAST LOCALIZED AREAS OF MORNING FOG AND/OR STRATUS MOST
DAYS...WITH GOOD CHANCES FOR AFTN/EVENING SHRA/TSRA EACH DAY.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       HIGH  86%     HIGH  90%     HIGH 100%     HIGH 100%
KGSP       HIGH  92%     HIGH  85%     HIGH 100%     HIGH  91%
KAVL       HIGH  80%     HIGH  94%     HIGH 100%     HIGH 100%
KHKY       HIGH  87%     HIGH  87%     HIGH 100%     HIGH 100%
KGMU       HIGH  86%     HIGH  85%     HIGH 100%     HIGH  91%
KAND       HIGH  91%     HIGH  87%     HIGH 100%     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...JPT
NEAR TERM...NED
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...NED



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