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Area Forecast Discussion

220
FXUS62 KGSP 010553
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
153 AM EDT SUN MAY 1 2016

.SYNOPSIS...
AN UPPER LOW WILL APPROACH THE AREA WITH A FRONTAL PASSAGE MONDAY
MORNING.  A SECOND MAJOR FRONT AHEAD OF A MASS OF COLD AIR FROM
CANADA IS EXPECTED BY THURSDAY.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 130 AM EDT SUNDAY...A BAND OF RAIN CONTINUES TO PUSH EAST OVER
THE PIEDMONT OF THE CAROLINAS...BUT WAS ON A WEAKENING TREND.
CURRENT THINKING IS THAT IT WILL NOT BE ENUF TO EXACERBATE ANY
PROBLEMS OVER ON THE S SIDE OF METRO CLT. WILL HAVE TO KEEP A FAIRLY
HIGH PRECIP PROBABILITY OVERNIGHT IN THE WAKE OF THIS RAIN AREA AS
RADAR SHOWS REDEVELOPMENT IN THE UPSLOPE AREAS OF N GEORGIA. TEMPS
WILL REMAIN MILD.

OTHERWISE...ONCE THE CONVECTION WANES WOULD NOT BE SURPRISED IF
PATCHY/WIDESPREAD FOG CONSUMES MUCH OF THE FCST AREA BY MORNING.
SUNDAY LOOKS FAIRLY SIMILAR TO TODAY ASIDE FOR THE ENTIRE FCST AREA
BEING FIRMLY IN THE WARM SECTOR.  SHEAR LOOKS A BIT BETTER AS A
PREFRONTAL TROF MOVES INTO THE REGION...WHILE ANOTHER PIECE OF H5
SHORTWAVE ENERGY DOES THE SAME.  STRONG/SEVERE CONVECTION IS
POSSIBLE ON SUNDAY WITH LARGE HAIL AND DAMAGING WINDS BEING THE
PRIMARY CONCERN AS SFC FLOW WILL BE VEERED THUS RESULTING IN LESS
FAVORABLE TORNADO CONDITIONS.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
AS OF 1205 PM EDT SATURDAY...UPPER HEIGHTS ATOP THE SE CONUS WILL
BEGIN TO FALL ON MONDAY AS SOUTHERN PLAINS ENERGY TRANSLATES
EASTWARD. THE RECENTLY POSTED OP RUNS OF THE 30/12 UTC NAM/GFS
SUPPORT THE 30/00 UTC ECMWF TREND OF THE MAIN LLVL BAROCLINIC
ZONE LINGERING NEAR OR NW OF THE CWFA. HENCE...IN CONJUNCTION WITH
THE DEVELOPING FAVORABLE UPPER LEVEL DYNAMICS...CHANCES FOR
DIURNALLY ENHANCED DEEP CONVECTION WILL BE INCREASING. INITIAL
THOUGHTS WILL BE FOR ON AN UPWARD BUMP IN TSTM PROBABILITIES MONDAY
AFTERNOON. CONTINUED UNSETTLED BUT LESS WARM WX CONDITIONS ARE
EXPECTED ON TUESDAY GIVEN THE PROGGED SLOW EVOLUTION OF THE MEAN
PATTERN FEATURING BROAD/DEEP SW FLOW AND THE SLOW SE SAGGING OF
ATTENDANT FRONTAL SYSTEM. WILL PLAN AND KEEPING SOLID MID-CHANCE
POP IF NOT AN UPWARD NUDGE TO LIKELY.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 130 PM SATURDAY...THE EXT RANGE WILL FEATURE A DEVELOPING
UNSEASONAL AND BROAD ERN CONUS ULVL TROF. THIS TROF WILL INTERACT
WITH A STATIONARY FRONT TRAPPED IN A DEEP MEAN SW/LY FLOW. THERE ARE
SIGFNT MODELED DIFFERENCES AS TO THE AMOUNT OF S/W ENERGY TRAVERSING
THE TROF...THE DEGREE OF ATL CYCLOGENESIS...THE AMOUNT OF LLVL COLD
AIR MAKING IT TO THE CAROLINAS...TILT OF THE ULVL TROF...AND
AVAILABLE MOISTURE. WITH THIS SAID...WILL MAINTAIN GRIDS CLOSE TO
THE PREVIOUS FCST. SINCE THE SYSTEM IS OUTSIDE THE NORMS FOR THIS
TIME OF YEAR WILL ALSO SIDE MORE WITH THE DYNAMICAL SOLNS AS OPPOSED
TO MOS GUIDANCE.

DO BELIEVE IT WILL BE A FAIRLY ACTIVE PERIOD WITH THE FRONTAL ZONE
BISECTING THE CWFA PROVIDING A FOCUSING MECHANISM FOR -SHRA AND
PERHAPS A COUPLE GENERAL TSTMS WED/THU AFTERNOONS. SOME DRIER AIR
LOOKS TO WORK IN AHEAD OF DEVELOPING OMEGA RIDGE FRI/SAT WHILE THE
SFC LOW PULLS NE OF THE AREA. THIS WILL CONFINE THE BETTER MOISTURE
ACROSS THE NC MTNS AND PERHAPS PRODUCE NON/ACCUM -SNSH THU NIGHT
ACROSS THE HIGHEST ELEVATIONS AS H85 TEMPS DROP TO -2 C ACCORDING TO
THE ECMWF...YET ONLY DOWN TO ARND ZERO GOING BY THE GFS. THU NIGHT
WILL BE THE COLDEST AT THE SFC AS WELL WITH HIGH ELEV TEMPS
DROPPING TO JUST ABOVE FREEZING. THIS SCENARIO WILL BE WATCHED FOR
POSSIBLE FROST/FREEZE CONCERNS. WITH CLOUD COVER LIKELY REMAINING
MCLDY/CLDY AND COOLER CP AIR MIXING BEGINNING THU...MAX TEMPS WILL
REMAIN NEAR NORMAL WED...WITH A DECREASE BY A COUPLE CATS THU/FRI
THEN A RETURN TO NORMAL LEVELS SAT AS SFC RIDGING ENGULFS THE SE
STATES.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...A MIXED BAG FOR THE REST OF THE OVERNIGHT
AND PROBABLY THROUGH THE MID-MORNING HOURS WITH VARIABLE CEILING AND
VISIBILITY DEPENDING ON LOCATION RELATIVE TO WAVES OF SHOWERS
EXPECTED TO MOVE ACROSS THE REGION. MOST PLACES WILL BE MVFR OR
IFR/LIFR THROUGH THAT TIME...WITH THE THOUGHT THAT IFR WILL
EVENTUALLY PREVAIL AFTER CURRENT BAND OF LIGHT PRECIP MOVES EAST.
THINK THE BIGGER PROBLEM WILL BE CEILING AND NOT VISIBILITY.
MEANWHILE...THERE WILL BE SOME VFR HOLES IN THE LOW CLOUD CEILING.
WIND GENERALLY SHOULD BE SE TO THE SOUTH OF AN OLD BOUNDARY RUNNING
ROUGHLY ALONG I-85...AND NORTHEAST TO THE NORTH OF THE BOUNDARY.
THIS IS EXPECTED TO WASH OUT WITH SE WIND TAKING SHAPE AT ALL PLACES
BY SUNRISE. UNCERTAINTY ABOUNDS FROM SUNRISE ONWARD ABOUT WHEN
SHOWERS/THUNDERSTORMS WILL OCCUR. THE LATEST GUIDANCE FROM
CONVECTION ALLOWING MODELS SUGGESTS IT WILL ACTUALLY BE A FAIRLY
QUIET DAY...BUT THIS TREND WAS NOT FOLLOWED YET. INSTEAD...HIT THE
AFTERNOON TSRA CHANCE WITH A PROB30 OR TEMPO AT ALL SITES. ENDED
PRECIP/RESTRICTION THREAT EVERYWHERE BY 00Z BASED ON GUIDANCE
SHOWING A WAVE MOVING PAST AROUND THAT TIME. MOST DETAIL BEYOND 00Z
MONDAY WAS ELIMINATED FOR BREVITY.

OUTLOOK...UNSETTLED WEATHER/OCCASIONAL CONVECTION/RESTRICTIONS ARE
EXPECTED TO CONTINUE INTO EARLY NEXT WEEK...AS A FRONT BECOMES
STALLED NEAR THE AREA. DEFINITIVE DRYING DOES NOT APPEAR LIKELY
UNTIL AT LEAST MID-WEEK.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
KCLT       MED   75%     MED   76%     HIGH  89%     HIGH 100%
KGSP       MED   76%     HIGH  85%     HIGH  99%     HIGH 100%
KAVL       HIGH  91%     HIGH  89%     HIGH  98%     HIGH  89%
KHKY       LOW   59%     MED   62%     HIGH  93%     HIGH  97%
KGMU       HIGH  81%     HIGH  84%     HIGH  99%     HIGH 100%
KAND       HIGH  80%     HIGH  84%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...SBK/WJM
NEAR TERM...CDG/PM/TDP
SHORT TERM...CSH
LONG TERM...SBK
AVIATION...PM



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