Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 011150 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 650 AM EST Mon Mar 1 2021 .SYNOPSIS... A cold front will cross the mountains early this morning and then cross the foothills and Piedmont through the late morning and early afternoon hours. Dry high pressure will build over from the north tonight into Tuesday. Unsettled weather returns from the west Tuesday night into Wednesday morning. Another low pressure system may affect the Gulf Coast region Friday into Saturday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 630 am EST: Regional radars show the leading edge of the heaviest shower band and gusty outflow winds pushing east across the foothills and Piedmont of the western Carolinas and NE GA. The heaviest rates will likely exit to the east later this morning, however, decent coverage of lighter rain/showers will persist through a good chunk of the day as a reinforcing surface cold front remains to the west and upper vorticity with a weak embeddd shortwave will cross the southern Appalachians. Additonal rainfall around one-half across the southwest NC mountains could create/exacerbate flooding issues there. Any problems will be minor and isolated so no Flash Flood Watches appear warranted. Instability remains quite marginal in profiles. Will generally keep thunder out of the forecast, but an isolated rumble cannot be completely ruled out with the fropa. Temperature trends will be hard to pin down today, with falling temps likely in the cold advection across the mountains, steady temperatures across the northern tier in balanced cold advection but warming post-fropa downslope flow, and a modest afternoon bump in temps in the western Upstate and NE GA. Gusty northwest winds will also develop in the cold advection through the day, but with gust values remaining below advisory criteria in the windiest mountain locations where a secondary, reinforcing cold fropa arrives this afternooon. The deeper moisture should settle generally southeast of our Piedmont counties by sundown along with the passing cold front. Any shallow upslope moisture into the western mountains will dry up fairly quickly in the cold air along the spine of the mountains this evening. So, any isolated snow showers or flurries will be short- lived and non-accumulating. 1031 mb surface high pressure will then build over the OH River valley tonight, with chilly thicknesses spilling southward east of the Appalachians.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 145 AM EST Monday...A split flow pattern aloft will evolve into a general trof over the period as a srn stream h5 low traverses the FA Tue night into Wed. A broad offshore sfc low will be supported by this upper energy and will bring a decent amt of GOM/Atl moisture to the area beginning Tue afternoon. Meanwhile, a cP sfc high will track off the midAtl coast and provide a weak insitu ridge before breaking down Wed morning. This general pattern will likely support a wintry mix of precip across the NC mtns Tue night, with light snow transitioning to freezing rain, then to rain by 15z Wed. The latest NAM soundings dropped across the NC escarpment show a strong and deep warm nose interacting with sub-freezing sfc temps abv 3.5 Kft to support -fzra, while the GFS is notably warmer with llvl partial thicknesses and indicates more of a sn/ip situation. So, have blended the llvl thermal profiles and used a top down approach for p/types, which generated arnd an inch of snow across the higher peaks with perhaps up to 2 inches over the Smokies. The freezing rain would begin arnd 08z and persist into mid morning with a few hundredths of an inch favoring the nrn BR escarpment. If these ice amts hold over the next few fcst cycles, an advisory may be issued. The atmos dries out during the day Wed as a Canadian high drops south and reinforces a srn stream sfc high building in from the west thru the period. Max temps will remain a little below normal each day, while mins hover arnd or a bit abv normal levels. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 210 AM EST Monday...The ext range fcst looks to remain quite dry as the models continue to show a suppressed large-scale pattern over the SE CONUS. Thus, little change was made to the already dry fcst. A stg subs zone will slowly cross the area, while a couple cP sfc highs build south and force a favored storm track well south of the FA each day. With winds generally maintained n/ly and weak CAA flow in place beginning Thu night, expect max temps to begin the period Thu abv normal, then cool a little below normal Fri thru Sun. Dewpoints will drop and mix out each afternoon, which could create some fire-wx concerns across NE GA based on RH each afternoon, except Sun when llvl moisture begins to return to the area. Winds shud remain relatively weak, however, and plenty of sunshine will be had making for rather nice days for early March. && .AVIATION /12Z MONDAY THROUGH FRIDAY/...
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At KCLT and elsewhere: The heaviest showers have aligned along the leading edge outflow of pre-frontal moisture, and this will be accompanied by briefly gusty northwest winds. Precipitation will become lighter throughout by late morning, and winds may toggle briefly back toward the southwest at all but KAVL ahead of a trailing, reinforcing cold front arriving this afternoon. During the best precip coverage this morning, anticipate mainly lower end VFR cigs with tempo MVFR at times. Visibility may go briefly IFR during the best downpours throughout. Expect a return to gusty northwest flow for the afternoon hours, with cigs generally returning to lower end VFR before gradually lifting and scattering by evening. Anticipate mainly just scattered high clouds tonight as drier high pressure builds in from the north. Most locations lose the gusts by early evening, but KAVL will be the exception with continued NW gusts into the 20s well into the nighttime hours. Surface winds will toggle more northeasterly at KCLT early Tuesday. Outlook: VFR conditions briefly persist into Tuesday under dry high pressure. However, moisture may surge back into the area by Tuesday night, with restrictions and precipitation chances returning through early Wednesday. Another round of drying is expected by late Wednesday, likely continuing through the end of the work week. Confidence Table... 12-18Z 18-24Z 00-06Z 06-12Z KCLT High 92% High 100% High 100% High 100% KGSP High 94% High 100% High 100% High 100% KAVL High 91% High 98% High 100% High 100% KHKY High 100% High 100% High 100% High 100% KGMU High 95% High 100% High 100% High 100% KAND High 95% 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
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&& .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...HG NEAR TERM...HG SHORT TERM...SBK LONG TERM...SBK AVIATION...HG

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