Area Forecast Discussion
Issued by NWS Greer, SC

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KGSP 010237 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 937 PM EST Sun Feb 28 2021 .SYNOPSIS... A cold front will cross Tennessee tonight then cross our area by mid day Monday. Dry high pressure will build over from the north as the high center moves from the Great Lakes to the Mid- Atlantic coast Monday night 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 MONDAY/...
-- Changed Discussion --
As of 935 PM: Low level moisture, and the resulting lower clouds, remain limited mainly across the mountains this evening, with mainly high clouds elsewhere. Without the low level moisture, the mechanical lift hasn`t resulted in any appreciable precip. Convection closer to the frontal zone also remains well to our west and north. While an isolated shower is possible across the mountains until midnight, the bulk of the showers should remain to our west until well after midnight. The forecast is on track with only minor changes for current conditions. Otherwise, potent short wave trough/upper low will dig from the Canadian prairie to the northeast Conus by the end of the period, allowing a fairly strong frontal zone to move across the TN and OH Valleys into the evening. A frontal band of convection will fill in across this region during the evening, as the front encounters moderate instability. In fact, the frontal band should be quite vigorous as it approaches the southern Appalachians late tonight, and the NC mountains are where the highest rainfall totals are expected across our forecast area through the period, with 1-2 inches appearing likely across the Smokies and vicinity. However, with meager-at-best instability expected across our area and lackluster upper air support, to go along with the typical high terrain disruption of the frontal circulation/low level convergence, the intensity and coverage of the frontal band is forecast to diminish as it moves across the forecast area Monday morning. As such, the threat of severe convection should remain west of the area, while any low end excessive rainfall threat will remain confined to extreme southwest NC. Despite the expected diminishing trend in the frontal band, it should hold together long enough to support categorical pops across the entire area during the morning. Precip should be all but done by mid-Monday afternoon. Winds diminish this evening before gusty SW winds redevelop across much of the area overnight into Monday morning. Gusty NW winds develop behind the front late morning into the afternoon. Min temps will be very warm tonight, and daily record warm lows...which are generally around 60 at the main climate sites...will be in jeopardy. After the very warm start Monday, developing cold advection will limit the diurnal heating potential, and only modest warming is expected across the mtn valleys and Piedmont/foothills, while temps will slowly fall throughout the day across the high elevations. This will likely negate any potential record warm lows as low temps for the day occur near midnight Monday night.
-- End Changed Discussion --
&& .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... As of 1205 pm EST Sunday: As sfc ridging rolls over into the region Monday night, the llvls will continue to dry, but model cross sections depict varying degrees of mid and upper level moisture lingering within the west to wsw flow aloft. Gridded model sky cover solutions are all over the place, and at this point, the generic partly cloudy should cover it. Downstream of developing southern stream low pressure, clouds should thicken again as Tuesday wears on and within the cool NE llvl flow, maximum temperatures will be back to below climo values. From late day Tuesday into Wednesday morning, as forcing and better moisture asscoiated with the encroaching southern stream system overspreads the region, pcpn will be become widespread. Vertical temperature/moisture fcst profiles over the NC mtns still suggest that a period of snow developing into a wintry mix remains possible during this time. Fast moving s/wv passage is expected on Wednesday, the axis of which is timed to be near the coast by the afternoon. Whatever the orientation and cvrg of pcpn shield is in the morning should be replaced by dry slotting by Wed afternoon. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 1215 pm EST Sunday: No change to the going dry and mild fcst for Thursday as extended range guidance remains in good agreement in progging deep layered dry air within the cyclonic flow aloft and a dry northerly llvl flow. Within the lingering llvl northerly flow, a dry cold front is progged drop south through the region on Friday ushering in another period of below climo temperatures. The mean pattern does not change very much for next weekend, featuring a lingering eastern CONUS trough. Forcing rounding the base of upper trough is progged to activate baroclinic zone, but way off to our south and into the offshore Atlantic on Saturday into Sunday. The dry conditions will continue with temperatures around 5 deg F below the early March climo each day. && .AVIATION /03Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
At KCLT and elsewhere: BKN stratocu across the mountains and SCT cu BKN cirrus will continue through the evening. Cigs lower to MVFR overnight ahead of the approaching cold front. Showers will move in with the lower cigs and move east by noon. Vsby restrictions are possible in the heavier showers, but timing too uncertain to include for now. Can`t rule out a rumble of thunder but prolonged TS looks unlikely given the lack of instability. Cigs return to low VFR by noon with those clouds scattering out during the afternoon. SW wind continues through the evening ahead of the cold front, SSW at KAVL. Gusts pick back up ahead of the front as well. Winds shift to NW behind the front and remain gusty. Winds briefly drop off some, possibly turning more westerly, early in the afternoon, then return to the NW becoming gusty once again. Outlook: VFR conditions expected Monday night and early Tuesday as dry high pressure briefly builds in. Moisture will then surge back into the area by the end of the day Tuesday, with restrictions and precipitation chances returning Tue night into early Wed. Another round of drying is expected by late Wed, likely continuing through the end of the work week. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 100% High 91% High 90% High 100% KGSP High 100% High 93% High 100% High 100% KAVL High 97% High 86% High 100% High 100% KHKY High 100% High 93% High 100% High 100% KGMU High 100% High 94% High 100% High 100% KAND High 100% High 94% High 98% 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:
-- End Changed Discussion --
&& .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...HG NEAR TERM...JDL/RWH SHORT TERM...CSH LONG TERM...CSH AVIATION...RWH is the U.S. government's official web portal to all federal, state and local government web resources and services.