Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 051740 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 1240 PM EST Sat Dec 5 2020 .SYNOPSIS... Another fast-moving system could bring light precipitation to our region Sunday night and Monday, and possibly another round of light snow for the mountains. Seasonably cool and dry weather is otherwise expected through Friday. && .NEAR TERM /THROUGH TONIGHT/... As of 1230 PM Saturday...Radars have gone quiet. Satellite imagery continues to show some low cloudiness over the nrn mountains, but cloud top temps have continued to warm to the point where no significant threat of snow exists, so precip prob has been removed for the rest of the day. The clouds should gradually diminish late in the day, as will the occasional wind gusts. Temps were in relatively good shape. Otherwise, the upper trof axis will continue to lift NE and off the Atlantic Coast today/tonight. This will result in a brief, nearly zonal upper pattern towards the end of the period early Sunday before the next round of upper-lvl energy approaches the fcst area from the north and west. At the sfc, the low pressure system will continue to move northward and up the Atlantic/New England Coast as broad high pressure spreads back over the region in its wake. This will make for a sunny and breezy Saturday for most of the CWFA with temps outside the mtns, near normal, if not a couple degrees below. Highs across the higher terrain will be 1 to 2 categories below normal. Clouds and light NW-flow snow showers will linger over the higher terrain and especially along the NC/TN border thru late morning. Any accumulations should remain below Advisory criteria, with the exception of a few isolated spots along the NC/TN border. As we move into the aftn, guidance has bndy layer moisture diminishing across the higher terrain and precip ending. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 100 PM Sat: A developing light pcpn event is still expected Sunday night as encroaching southern stream energy aids in blossoming pcpn shield northeastward from the Gulf of Mexico. Ensembles continue to adverise mean QPF of less than a tenth of an inch through daybreak Monday and mainly limited to the piedmont. In the critical chillier air over the mountains, thermal profiles still support frozen pcpn, but with only a few hundreths liquid accum expected, hard to believe that any pre-dawn light snow accums would be seen outside of the higher elevations of the SW mtns. In conjunction with potent looking northern stream vort, showers are expected to redevelop and expand on Monday, especially in the mountains in conjunction with llvl caa and upslope flow. Temperatures will remain cool enough across the higher elevations for accumulating snow, maybe even for a higher elevation advisory level event, into Monday evening. With clouds and caa keeping maxes well below normal and vertical temp profiles becoming increasingly supportive of frozen pcpn even across the lower elevations as Monday wears on, will be monitoring the situation closely to see if there is enough lingering moisture to carry precip downstream of the mountains. After a chilly start to the day on Tuesday, widespread 20s for morning minumums, a sunny, brisk and chilly day is on tap featuring maximum temperatures several categories below climo. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 240 AM Sat: One more trailing shortwave is progged to traverse the area Tuesday as upper trough shifts offshore, but without any moisture to speak of. A broad ridge will replace these features, bringing dry wx and moderating temps to the South Wednesday thru Friday. Maxes will be a couple categories above normal Thu and Fri, in the upper 50s and lower 60s for the mtn valleys and Piedmont. One or more shortwaves will reach the Plains by the end of the work week; GFS and ECMWF both depict cyclogenesis such that a cold front approaches the area Friday night. The CMC GDPS instead shows the sfc low crossing the Great Lakes. Given this disagreement, and this development being very close to the end of the period, precip chances are being kept below the mentionable threshold thru 12z Sat. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... At KCLT and elsewhere: VFR through the period, with only a few stratocu across parts of NC through sunset. A few gusts are possible at the NC sites as well. All this should diminish with sunset, leaving us with clear sky and a light N or variable wind overnight as high pressure settles in. Sunday should start out clear, with wind returning light from the SE/S. Some high clouds will start to invade in the afternoon. Outlook: Moisture will return Sunday night with cig restrictions possible at times on Monday as another low pressure system lifts out of the Gulf and up the Atlantic Coast. Once that system departs Monday night, the rest of the period should be VFR. Confidence Table... 17-23Z 23-05Z 05-11Z 11-12Z KCLT High 100% High 100% High 100% High 100% KGSP High 100% High 100% High 100% High 100% KAVL High 100% High 100% High 100% High 100% KHKY High 100% High 100% High 100% High 100% KGMU High 100% High 100% High 100% High 100% KAND High 100% 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 are available at the following link: www.weather.gov/gsp/aviation && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...Wimberley NEAR TERM...JPT/PM SHORT TERM...Wimberley LONG TERM...Wimberley AVIATION...PM

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