Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 301344
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
944 AM EDT MON MAR 30 2015

.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE REGION THIS MORNING AHEAD OF
REBUILDING HIGH PRESSURE FOR TUESDAY.  ANOTHER WEAK COLD FRONT WILL
ARRIVE ON TUESDAY NIGHT WITH HIGH PRESSURE QUICKLY BUILDING FOR
WEDNESDAY LASTING THROUGH THURSDAY.  FRIDAY NIGHT WILL BRING THE
PASSAGE OF ANOTHER COLD FRONT...WITH COOLER AND DRIER HIGH PRESSURE
PREVAILING FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 930 AM...THE BAND OF PREFRONTAL SHOWERS AND THUNDERSTORMS HAVE
EXITED THE CWA TO THE EAST...WITH ONLY UNION COUNTY UNDER LIGHT RA.
THE CWA SHOULD BECOME DRY OVER THE NEXT HOUR. I WILL UPDATE THE
FORECAST DECREASE POPS AND QPF ACROSS THE CWA. IN ADDITION...I WILL
INCREASE SKY COVER AND SLOW THE MORNING DIURNAL WARMING RATE. THIS
AFTERNOON...THE COLD FRONT WILL PUSH OVER THE PIEDMONT...RESULTING
IN LIGHT DOWNSLOPE FLOW. CLEARING SHOULD OCCUR THROUGH THE AFTERNOON
HOURS. HOWEVER...SLOW WARMING THIS MORNING WILL PLACE THE CURRENT
FORECAST OUT OF PACE FOR HIGH TEMPERATURES. THE UPDATE WILL ALSO
FEATURE HIGH TEMPERATES SEVERAL DEGREES COOLER...WITH AROUND 60
WITHIN THE MTN VALLEYS TO MID TO UPPER 60S EAST.

AS OF 630 AM...LARGE AREA OF RAIN...WITH EMBEDDED THUNDERSTORMS...
WAS MOVING VERY RAPIDLY ACROSS SRN NC/UPSTATE SC/NE GEORGIA...DRIVEN
EWD BY A STRONG LOW LEVEL JET. HAVE RAISED PRECIP PROB TO
CATEGORICAL MOST PLACES S OF I-40 BASED ON RADAR TREND. SOME PLACES
COULD PICK UP AN INCH OR SO OF PRECIP WHERE THE MODERATE RAIN IN THE
TRAILING STRATIFORM REGION LINGERS LONGEST. TEMPS WERE TWEAKED BASED
ON OBS. THE MODELS TAKE THE BAND OF PRECIP AHEAD OF THE FRONT
EASTWARD ACROSS THE FCST AREA FAIRLY RAPIDLY THIS MORNING...AS THE
SHORT WAVE ROTATES QUICKLY AROUND THE BOTTOM OF THE UPPER TROF. THIS
SHOULD DRIVE THE SURFACE FRONTAL ZONE EAST OF THE REGION BY MIDDAY.
COVERAGE SHOULD BE NOT AS GREAT ALONG/N OF I-40 WHERE DOWNSLOPE E OF
THE MTNS WILL BE UNFAVORABLE. PRECIP CHANCES RAMP DOWN QUICKLY BY
MIDDAY. TEMPS SHOULD REBOUND NICELY...ABOUT TEN DEGREES ABOVE
YESTERDAY...IN SPITE OF THE SFC BOUNDARY MOVING THRU...BECAUSE OF
THE W/NW DOWNSLOPE FLOW IN THE AFTERNOON.

TONIGHT SHOULD BE QUIET AS HIGH PRESSURE BUILDS BACK IN FROM THE NW.
MIN TEMPS WILL BE BELOW NORMAL AGAIN. THERE ARE SOME MINOR CONCERNS
FOR FROST/FREEZE OVER THE MTNS...BUT THE TEMPS BELOW 32F ARE MAINLY
CONFINED TO THE HIGHER ELEVATIONS...AND THE FROST POTENTIAL DOES NOT
APPEAR TO BE THAT GREAT BASED ON DEWPTS.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM EDT MONDAY...THE SHORT TERM FCST PERIOD INITIALIZES
TUESDAY MORNING AMIDST CONTINUED NW FLOW PATTERN ALOFT...HIGHLIGHTED
BY A NORTHERN STREAM SHORTWAVE SLIDING THROUGH THE SOUTHERN GREAT
LAKES REGION.  WEAK SURFACE CYCLOGENESIS BENEATH WILL AID COLD FRONTAL
PROGRESSION ACROSS THE MIDWEST INTO THE OHIO VALLEY ON TUESDAY AHEAD
OF SPRAWLING HIGH PRESSURE.  MEANWHILE ACROSS THE SOUTHERN PLAINS
ANOTHER SURFACE WAVE WILL FORM IN THE LEE OF THE SOUTHERN ROCKIES
ALLOWING FOR DEVELOPMENT OF MODEST BAROCLINIC ZONE OVER THE
SOUTHEAST TUESDAY AFTERNOON INTO WEDNESDAY.  WARM FRONT LEADING THE
CHARGE NORTHWARD ON TUESDAY WILL ADVANCE INTO THE I20 CORRIDOR LATE
IN THE DAY WITH ACTIVATION LIKELY AS MORE UNSTABLE AIR ADVECTS
NORTHWARD.  AS THE ABOVE MENTIONED COLD FRONT CONTINUES TO SLIDE
SOUTH THROUGH THE TN VALLEY...EXPECTING CONVECTION ALONG THE FRONTAL
ZONE WHICH COULD PUSH INTO THE WESTERN NC MTNS LATE TUESDAY NIGHT.
MODELS CONTINUE TO HINT AT SOME RESIDUAL INSTABILITY AFTER SUNSET
AHEAD OF THE FRONT...HOWEVER DECREASING WITH HEATING LOSS...AND
DRIER AIR ADVECTION BEHIND THE FRONT AS IT BACK DOORS INTO THE
REGION.  THE FRONT WILL SLIDE SOUTH THROUGH THE REMAINDER OF THE
FCST AREA OVERNIGHT...AS HIGH PRESSURE SETS UP ALONG THE EASTERN
SEABOARD.  BRIEF HEIGHT RISES ALOFT COMBINED WITH RIDGING AT THE
SURFACE WILL KEEP THE WX DRY ON WEDNESDAY AHEAD OF RETURNING MOIST
SOUTHERLY UPGLIDE ATOP POSSIBLE INSITU CAD THURSDAY MORNING.

AS FOR THE FCST...POPS WILL SLOWLY INCREASE INTO TUESDAY EVENING
ACROSS THE NORTHEAST GA AND WESTERN NC MTNS TO ACCOUNT FOR WEAK
FRONTAL ZONE ASSOCIATED CONVECTION...WITH POPS REMOVED BY MID
MORNING WEDNESDAY AS THE COLD FRONT SLIDES THROUGH.  POPS WILL
REMAIN BELOW MENTIONABLE LEVELS THROUGH THE DAY WEDNESDAY BEFORE
INCREASING MID/LATE EVENING AS MODELS CONTINUE TO HINT AT WEAK
INSITU CAD REGIME ON THE WESTERN FLANK OF THE COASTAL SFC RIDGE.  GFS
ISENTROPIC CHARTS INDICATE IMPROVING UPGLIDE IN THE LOW
LEVELS...THUS CHANCE LEVEL POPS WERE FAVORED OVER THE WESTERN HALF
OF THE FCST AREA TAPERING TO SLIGHT CHANCE FURTHER EAST ON THE
FRINGE OF UPGLIDE MAXIMA.  TEMPERATURES THROUGH THE PERIOD WILL
REMAIN ABOVE NORMAL LEVELS DESPITE THE WEAK FROPA TUESDAY NIGHT.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 315 AM EDT MONDAY...THE MEDIUM RANGE FCST PERIOD INITIALIZES
THURSDAY MORNING AMIDST ONGOING UPGLIDE/UPSLOPE PRECIP ACROSS MUCH OF
THE SOUTHWEST NC AND NORTHEAST GA MTNS.  WEAK INSITU CAD REGIME
RESULTANT FROM ANCHORED COASTAL HIGH OFF THE NC COAST WILL BREAK
DOWN THROUGH LATE MORNING LEADING TO EROSION OF ANY UPGLIDE
ENHANCEMENT.  SOUTHERLY FLOW AT THE SURFACE WILL CONTINUE LEADING TO
IMPROVING WAA REGIME INTO FRIDAY.  MEANWHILE...A NORTHERN STREAM
UPPER WAVE WILL SLIDE ACROSS THE UPPER MIDWEST WHILE A COLD FRONT
STRETCHES TO THE SOUTH FROM SUBSEQUENT SFC LOW.  MODELS CONTINUE TO
PROG THE FRONT ALONG THE OH RIVER VALLEY THURSDAY EVENING WITH AN
IMPROVING WARM SECTOR AIRMASS OUT AHEAD.  THE ECMWF/GFS TREND
TOWARDS SOME DISCONTINUITY LATE IN THE WEEK REGARDING TIMING OF THE
FROPA ACROSS THE SOUTHERN APPS.  THE ECMWF FAVORS A FASTER SOLUTION
WHICH BRINGS THE FRONT INTO THE MTNS OF WESTERN NC FRIDAY AFTERNOON
OR EARLY EVENING WITH PERHAPS ISOLATED CONVECTION AHEAD IN THE
MILDLY UNSTABLE AIRMASS...WHILE THE GFS SEEMS ABOUT 6 HOURS SLOWER
THAN THAT OF THE ECMWF.  BOTH SOLUTIONS WOULD FAVOR A NOCTURNAL
FROPA THUS LIMITING THE AMOUNT OF POTENTIAL INSTABILITY AVAILABLE
FOR CONVECTION.  BEYOND THAT THE FRONT SHOULD EXIT THE REGION TO THE
EAST BY MIDDAY SATURDAY AT THE LATEST ALLOWING FOR COOLER/DRIER HIGH
PRESSURE TO ADVECT IN FROM THE WEST.  TEMPERATURES THROUGH THE
PERIOD WILL WARM TO WELL ABOVE NORMAL LEVELS FOR THURSDAY AND
FRIDAY...WITH SLIGHTLY COOLER YET STILL ABOVE CLIMO LEVELS FCST FOR
THE WEEKEND.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
AT KCLT...BAND OF PRECIP AHEAD OF FRONT WILL MOVE ACROSS THE
AIRFIELD THROUGH ABOUT 14Z. EXPECT THE HEAVIER PRECIP AND EMBEDDED
THUNDERSTORMS TO MOVE S OF THE AIRFIELD...SO WILL NOT CARRY A TSRA.
THE PRECIP SHOULD HELP BRING THE CEILING DOWN INTO THE LOWER END OF
THE MVFR RANGE...BUT THE MODEL GUIDANCE SUGGESTS THAT ANY MVFR
CEILING WILL NOT FORM UNTIL AFTER THE HEAVIER RAIN MOVES OFF TO THE
EAST. WIND SHOULD STAY SW UNTIL MIDDAY WHEN THE FRONTAL ZONE REACHES
THE SRN PIEDMONT. EXPECT THE WIND SHIFT AROUND 17Z...FIRST TO
WESTERLY...AROUND THE SAME TIME THE LOW CLOUDS MOVE OUT...AND THEN
TO NW BY MID AFTERNOON WHEN THE CLOUDS SCATTER OUT FOR GOOD. THE
REST OF THE FCST WILL BE VFR WITH ONLY CIRRUS AND A NW TO N WIND
OVERNIGHT.

ELSEWHERE...THE BAND OF PRECIP SHOULD MOVE EAST OF THE TERMINALS BY
14Z OR SO. AN MVFR CEILING IS EXPECTED ON THE BACK SIDE OF THE RAIN
AREA BASED ON MODEL GUIDANCE AND UPSTREAM OBSERVATIONS. THE LOWER
CLOUDS SHOULD SCATTER OUT AS THE FRONTAL ZONE MOVES THROUGH DURING
MIDDAY. HAVE INCLUDED THUNDER AT THE UPSTATE TAF SITES BASED ON
EMBEDDED LIGHTNING...THRU 14Z. THERE COULD BE SOME GUSTY NW WINDS
BEHIND THE FRONT AT KAVL THROUGH SUNSET.

OUTLOOK...VFR TUESDAY THROUGH WEDNESDAY. AN APPROACHING WARM FRONT
AND RESULTANT MOISTURE RETURN WILL BRING BETTER CHANCES FOR
PRECIP/RESTRICTIONS ACROSS THE AREA LATER IN THE WEEK...PERHAPS
STARTING THURSDAY MORNING. EVENTUALLY...A SLOW MOVING COLD FRONT
WILL AFFECT THE AREA FRIDAY OR SATURDAY WITH MORE RESTRICTIONS.

CONFIDENCE TABLE...

            13-19Z        19-01Z        01-07Z        07-12Z
KCLT       HIGH  85%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       MED   70%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  85%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       MED   69%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       MED   77%     HIGH 100%     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...CDG
NEAR TERM...NED/PM
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...PM


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