Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 241115 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 715 AM EDT Tue Oct 24 2017 .SYNOPSIS... Drier and cooler air will sweep into the region today leading to possible frosty conditions Wednesday and Thursday mornings. Dry conditions are expected to persist through the remainder of the work week before another front moves in next weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 655 AM EDT: Visibility in fog remains quite variable over the NC piedmont this morning, so will continue with the Special Weather Statement for patchy dense fog through 9 AM. Otherwise, a weak surface trough axis will linger along the Blue Ridge in westerly flow today. Meanwhile, the deepening upstream trough axis will move east toward the Appalachians, with a broad area of mid-level DPVA and steepening lapse rates reaching the NC mountains this afternoon. A few showers could result over the high terrain, but profiles remain relatively dry so will limit any low PoP mention to just the western mountains and higher ridges. The trough axis will bring a reinforcing shot of cooler air to the region late today through tonight. Shallow northwest flow moisture will also arrive in the western mountains late tonight and a few high elevation snow showers could mix in late, but with no accumulations expected. The colder temperatures will permit many mountain locations to experience near freezing minimum temperatures. Frost issues appear limited by the continued mixing and possibly increasing clouds late. Still, freeze warnings will likely be needed across the northern mountains and also Haywood County, and conditions will need to be monitored for possible expansion or new Frost Advisories later today for tonight. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 200 AM EDT Tuesday: The short term fcst period kicks off on Wednesday morning amidst deep full latitude H5 troffing across the eastern CONUS, while ridging builds over the Desert Southwest. At the surface, broad cool/dry high pressure centered westward across central TX will extend well to east into the southern Appalachian region at fcst initialization, with it`s center moving eastward over the central GOM by Thursday morning. Closer to home this pattern will yield dry weather and below normal temperatures. With that, guidance does favor possible freeze conditions at fcst onset with frost possibly hindered to some degree by light winds. However on Thursday morning the PG will be relaxed a bit yielding improved frost conditions across the low terrain, as well as freezing temperatures across the northern mtns and in the central/southern mtn valleys. On top of that, guidance continues to favor some reinforcing moisture thanks to a passing shortwave among the mean flow aloft, which looks to impact the western slopes of the Apps into Thursday morning. Profiles at that time will support wintry precip in the form of snow showers, thus such will be included in the fcst at the higher peaks with no accumulation expected. Beyond that the pattern begins to modify as the upper trof ejects over the western Atl and shortwave H5 ridging moves across the southeast states. In response, the surface anticyclone will move onshore Thursday afternoon and continue moving to the northeast along the Atl shoreline through the remainder of the period. This pattern will favor sly backed surface flow and thus a weak waa regime leading to improved temperatures/dewpoints. Therefore the fcst will feature temperatures nearly 8-10 degrees below normal on Wednesday as well as Thursday morning, warming a few degrees for Thursday afternoon yet still nearly a cat/two below normal. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 230 AM EDT Tuesday: The medium range fcst period picks up on Friday morning amidst an increasingly amplified upper pattern highlighted by weak ridging along the east coast, while a sharp full latitude trof consumes the Rockies/Plains with a region of surface cyclogenesis over the upper Midwest driving a cold front into the MS River valley. Pattern evolution through the period will feature continued waa across the southeast into Saturday as the aforementioned cold front approaches out of the TN valley by mid/late day. Ahead of the front, moisture advection will increase warranting elevated pops in the upslope favored regions first then spreading out across the cwfa overnight into Sunday morning. By that point guidance seems to be in better agreement than previous runs in that front will be moving into western NC, possibly with a line of convection to accompany. The front will push across northeast GA and the western Carolinas on Sunday warranting healthy pops regionwide, eventually moving out overnight into Monday morning. At that point thermal profiles will be cooling rapidly given the strength of post frontal caa therefore lingering moisture across the high terrain could yield the first measurable nwfs event just in time for our snowfall season to begin at the first of November. Temperatures through the medium range will initialize warm at near normal levels, cooling a bit Saturday/Sunday given increased coverage of clouds/precip, then falling to below normal into Monday. && .AVIATION /11Z TUESDAY THROUGH SATURDAY/... At KHKY: Communications to the KHKY ASOS remain down since the Monday severe storms affected the airfield. AMD NOT SKED will be featured there until further notice. Low clouds and fog could appear at times through 13Z given the abundant ground moisture along with clear skies and slackening winds. Some drying has occurred from the west so will keep cloud bases scattered for now, with fog limited to MVFR. However, IFR to LIFR conditions are certainly possible for an hour or so. Expect an uptick in WSW flow today with mainly high clouds and then winds adjusting more WNW tonight. At KCLT and elsewhere: Skies have cleared at the TAF sites. Ground moisture will raise the potential for some low clouds and fog at KCLT through 13Z. Will keep low cloud bases there scattered for now. Otherwise, expect light W to SW flow, NW at KAVL, becoming slightly gusty through the day with mixing. VFR conditions are expected throughout despite the approach of a robust trough from the west tonight. Winds may toggle more WNW tonight. Outlook: Drier and cooler conditions will continue through Thursday. Deep moisture will return ahead of another cold front over the weekend. Confidence Table... 11-17Z 17-23Z 23-05Z 05-06Z 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 94% 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 and ensemble forecasts are available at the following link: www.weather.gov/gsp/aviation && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...Freeze Warning from 1 AM to 9 AM EDT Wednesday for NCZ033-049- 050-052. SC...None. && $$ SYNOPSIS...CDG NEAR TERM...HG SHORT TERM...CDG LONG TERM...CDG AVIATION...HG

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