968 FXUS62 KGSP 160305 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 1105 PM EDT Sat Oct 15 2022 .SYNOPSIS... A weekend warm-up continues for the region as high pressure builds across the area ahead of a strong cold front. This strong cold front arrives from Kentucky and Tennessee then crosses our region on Monday. Much colder air will descend into the area bringing the coldest air of the season through the middle of the week. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 1035 PM EDT Saturday: As expected, the area of sct showers over NE Tennessee fizzled out as it approached the NC border a few hours ago. I'm not expecting any additional shower activity thru the overnight/morning with cloud cover gradually increasing from the NW Sunday morning. The mostly clear skies and relatively low dewpts should allow for good radiational cooling, although the pressure gradient may remain sufficient to support areas of weak mixing across the Piedmont. The potential is there again for the sheltered mtn valleys to crater shortly before sunrise. Thus, low temps are fcst right around climatology across much of the Piedmont and Foothills, and below climo across the valleys. Otherwise, a long wave trof over the east will sharpen thru the near-term period as a strong speed max digs into the western Great Lakes toward the end of the period. This will activate an associated baroclinic zone from the southern Great Plains into the Tennessee Valley Sunday afternoon and evening. In the interim, another round of mostly token chance PoPs are carried across our northern and western zones to account for the potential for showers and perhaps a thunderstorm or two before the front arrives. Otherwise, high temps are expected to be even warmer than Saturday, with values about 6 to 10 degrees above climo over most areas. && .SHORT TERM /MONDAY THROUGH TUESDAY/... As of 115 PM Saturday: Broad upper low will bring rapid height falls into the area through the short term as an attendant cold front encroaches the region from the northwest Sunday night. A stout upper jetlet and southwesterly flow through the lower half of the troposphere will align with the main frontal zone ahead of the cold front Sunday night into Monday morning. This should allow for scattered showers with a few rumbles of thunder possible with elevated instability being indicated in profiles. The cold front is expected to slip through the CFWA by Monday afternoon, but if guidance tries to push the forward progression back any slower, instability may uptick and allow for at least scattered or a broken line of convection east of the mountains Monday afternoon due to the fropa occurring at peak heating. The best chance would be along and east of I-77, but as of now, the cold front is forecasted to instigate a fropa before peak heating of the day and thus, should lower convective chances and keep PoPs in the forecast until daybreak Monday. The best upper forcing will also shift into the eastern Carolinas by peak heating as well, which will reduce convective chances even more. Strong CAA will filter in behind the front as heights continue to fall and a stout Canadian surface high dips into the central CONUS. Expect gusty northwesterly winds and colder temperatures as a result, especially over the mountains Monday night into Tuesday as the area enters a true post-frontal regime. Temperatures will remain above normal Sunday night as extensive cloud cover and precip will be over the CFWA, while temperatures Monday manage to reach near- normal values, just ahead of the cold front. Temperatures take a very cold turn as lows Monday night drop to around 10 degrees F below normal as strong CAA and decent radiational cooling conditions settle over the region. Expect freeze conditions to prevail over the mountains, while frost advisories will be likely along the I-40 corridor and north and west of the I-85 corridor Monday night. Despite dry conditions and mostly sunny skies, expect max temperatures on Tuesday to be 12-18 degrees F below normal, feeling more like late November/early December than mid-October as broad upper troughiness and CAA remains over the eastern CONUS. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 215 PM Saturday: Upper troughiness over the eastern CONUS will continue to deepen through the middle part of the week. Expect height falls to continue through Wednesday, which will allow our temperatures to remain 12-18 degrees F below normal for highs and lows through Wednesday night. Expect widespread freeze in the mountains and foothills, while locations in the northern Upstate and along the I-40 corridor will flirt with the freezing mark. Elsewhere will likely experience frosty conditions Tuesday and Wednesday night, which essentially puts an end to the growing season for the year. The base of the trough axis should move across the area Wednesday into Wednesday night.This should allow for the airmass to gradually modify through the end of the period as broad high pressure sets up shop over the CFWA through the end of the work week. Temperatures will remain a few degrees below normal through Friday night. Model guidance have picked up on a cutoff low from the base of the trough as it dips the low into Florida and eventually meander off of the Southeast coast through D7. This could fetch moisture back into the region, but would mostly stay confined to the Coastal Plains. Expect dry conditions through the medium range. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: VFR conditions are expected to persist thru the 00z taf period. With moisture increasing, the potential for fog will be higher in the mtn valleys Sunday morning, yet fog still appears most likely in the valleys west of KAVL (if it actually materializes). Otherwise, high clouds will increase thru the day tomorrow, with KAVL and KCLT likely going bkn by the end of the taf period. In addition, I included a PROB30 for SHRA at KAVL and KHKY for the last few hours of the period, but held off on any mention of precip for the other taf sites for the time being. Winds will be light tonight/overnight and continue to favor a SWLY direction at most sites. They will pick up again out of the SW by late morning and remain SWLY thru the day. The only exception will be KAVL, where winds will favor more of a NWLY direction tomorrow. Outlook: There will be an uptick in shower chances from the NW Sunday evening and early Monday along with the arrival of the next cold front. Frost/freeze conditions could impact operations each morning from Tuesday onward, but with VFR conditions still likely at most sites. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...DEO NEAR TERM...JPT SHORT TERM...CAC LONG TERM...CAC AVIATION...JPT