Area Forecast Discussion
Issued by NWS Greer, SC

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000 FXUS62 KGSP 271507 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 1007 AM EST Sat Feb 27 2021 .SYNOPSIS... A front stalled south of the region today will gradually lift northward as a warm front through Sunday. A cold front will approach the southern Appalachians from the northwest Sunday night and cross the area on Monday. Dry high pressure will build over from the north Monday night into Tuesday before unsettled weather returns from the west Tuesday night into Wednesday. A stronger storm system could arrive by Friday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 950 AM: The CWA remains under a decaying CAD setup, with parent high already well off the East Coast and continuing to distance itself from our area, and low-level winds veering such that upglide over what`s left of the wedge will diminish, if not already. That said, strong inversion is expected to limit mixing, and cloud cover looks pretty stubborn this aftn. Have increased cloud cover thru the day, and brought max T values down a bit. However, any insolation will lead temps to rebound rapidly wherever breaks/scattering do occur; warmest airport site in the CWA is Jackson Co Arpt which cleared out for a time and already hit 60, compared to temps near 40 in the NW NC Piedmont. Thus, still expecting most of the area to rise into the 60s by mid-aftn, with even the "wedgier" guidance showing values near 60 without any contribution from MOS. The sub-trop ridge becomes the dominant feature thru the rest of the period as a warm/stat front develops just to the NW of the area. Will maintain low-end chance PoPs across the NC mtns this afternoon and thru the overnight within continued moist mech lift; the previous fcst values from early morning still look good. Pockets of h5 vort energy will traverse the aforementioned frontal zone today and enhance the convective potential. By the afternoon/evening general thunderstorms are possible along the nrn TN/NC spine, with most of this activity developing on the TN side, however, a couple tstms are possible across the nrn NC mtns as well. With increasing llvl GOM moisture and stratus likely developing overnight, expect mins to be held quite a bit abv normal with readings generally in the 50s over most locales.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 230 am EST Saturday: Deep layer southwesterly flow will continue over the southeastern U.S. on Sunday, with a split flow pattern developing back over the western and central CONUS. Meanwhile, deeper moisture will remain wrapped north and west of our area through the day on Sunday along a stalled frontal boundary. The southwest flow and associated warming of 850 mb temps will permit maxes to run well into the 70s for many areas Sunday afternoon, with PoPs for showers generally confined to northern and western sections. The more progressive northern stream will send shortwave energy into the lower Ohio Valley Sunday night, while the southern stream develops into a cutoff low over west Texas. The northern stream trough will cross the southern Appalachians Monday and push a cold front through the region. The deepest moisture and forcing ahead of the sagging cold front will occur late Sunday night into Monday morning, with drying from the northwest Monday afternoon. QPF amounts are down slightly given the better forward movement of the boundary on recent model runs. Instability with the fropa will be modest as well, so neither hydro nor severe appear to be prominent concerns - although a heavy rain mention will be continued in the mountains in the HWO for very isolated, minor flooding late Sunday night. Right entrance region upper jet divergence will cross the area late Monday post fropa, however, deep-layer drying will have developed by then and dry profiles continue through Monday night in the northwesterly flow. The only exception will be very shallow northwest flow moisture in the NC mountains Monday night, but any brief snow shower or snow flurry activity looks quite isolated at best along the spine of the northern mountains. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 230 am EST Saturday: Disparate solutions exist among the models in the Tuesday timeframe with regards to the handling of the southern stream low/trough evolution eastward from the southern plains to the lower MS River Valley. The ECMWF has considerably more forcing and associated moisture through mid week, with the GFS drier. Will keep a chance PoP mention in the forecast for Tuesday night and Wednesday at present during the best consensus period. Given the strength of the high to the north, and chilly thicknesses in place on Tuesday, there is some potential for mixed mountain/nrn tier ptypes at onset Tuesday night. The passing upper energy will move east of the area on Thursday, with a relative lull in the forecast expected. The next robust southern stream system may begin to approach the Deep South on Friday. Anticipate moisture spilling back into the region from the west ahead of this system Thursday night through Friday, but again with considerable model uncertainty. Will focus the best chance PoPs for showers on Friday. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
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At KCLT and elsewhere: Low-end flight cats will continue or develop this morning across all TAF sites as a shallow sfc wedge begins to weaken and moisture levels remain high. Expect KCLT to remain IFR or worse thru midday. Conds improve slowly by the afternoon, with most sites going VFR, as hipres works across the OH Valley and mixes in llvl dry air. Northeasterly winds will switch to a sw/ly direction by mid morning as the sfc wedge continues to breakdown and the synoptic pattern favors an Atl ridge axis. A return of llvl moisture overnight will generate IFR/LIFR CIGs aft 09z or so thru the morning hrs. Outlook: Scattered to numerous showers with associated flight restrictions are expected to return Sunday and linger into early next week. Drier hipres will build back into the area by Tuesday. Confidence Table... 15-21Z 21-03Z 03-09Z 09-12Z KCLT Med 68% High 81% High 100% High 80% KGSP High 90% High 96% High 100% Med 78% KAVL High 83% High 95% High 100% Med 68% KHKY Med 73% High 88% Med 66% Med 77% KGMU High 85% Med 70% High 100% Med 77% KAND High 88% High 81% High 95% High 83% 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...SBK/Wimberley SHORT TERM...HG LONG TERM...HG AVIATION...SBK/Wimberley

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