102 FXUS62 KGSP 160707 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 307 AM EDT Sun Oct 16 2022 .SYNOPSIS... Warm temperatures and a quick round of showers for some of the area will end the weekend ahead of a strong cold front moving into the region Monday. The coldest air of the season so far will reach the area and bring about widespread freezing temperatures and frost for most of the week. && .NEAR TERM /THROUGH TONIGHT/... As of 305 am EDT Sunday: IR satellite imagery shows a large shield of mid and high-level cloudiness streaming east from decaying convection over the middle Mississippi River Valley early this morning. The leading edge of this should thin a bit, but still expect an increasing mid/high cloud trend today given swift zonal flow aloft. This might cap maximum temperatures a touch under those supported by the warming thicknesses. Meanwhile, a weak and dissipating surface front remains stalled across western NC this morning. This boundary will further frontalyze as a much more potent cold front moves through the Ohio River Valley late in the day. Chance PoPs will build across northwest sections through the afternoon hours as very modest instability returns with recovering dewpoints ahead of the front. The upstream boundary will then quickly be on the move southeast tonight. Frontal circulations will combine with upper-level divergence near the right entrance region of a passing upper jetlet to force fairly solid likely to categorical shower coverage in northwest sections tonight. Indeed, the latest convection-allowing models all have robust coverage of showers and embedded thunderstorms, especially over western NC, from 03Z to 09Z. Surface- based instability should be limited to a few hundred J/kg of SBCAPE just ahead of the approaching front, with 850 to 500 mb lapse rates generally near 6.5 deg C/km. Deep-layer bulk shear will likely reach 40 to 50 kt along the northern Blue Ridge by midnight, and a 35+ kt low-level jet could transit east along the I-40 corridor through the early morning hours. Most of the better HREF updraft helicity streaks are west and north of the forecast area, but convection may need to be monitored with the approaching frontal zone into the overnight hours. The current Day 1 Marginal severe thunderstorm risk looks well-placed. Coverage may wane as the boundary moves southeast across the region and ongoing activity encounters drier profiles and lessening nocturnal instability. Anticipate our final night of warm mins for a while, with temperatures mostly in the 50s. Fog could become a problem in the NC mountains by daybreak with continued low- level moisture. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 230 AM Sunday: A strong upper trough across the Great Lakes region will extend into the CWA on Monday. As the trough and associated low in Canada strengthen, heights should continue to fall throughout the region. A strong cold front will sweep across the area Monday morning into the afternoon, with plenty of cold air behind it. Backing winds will inject much colder and drier air throughout the forecast period and beyond. Any showers from prior to the front should rapidly taper off Monday morning with slight chance PoPs in the far western portion of the western Carolina mountains. High temperatures on Monday ahead of the FROPA will rise well above climo, with upper 70s in the Piedmont and upper 60s in the western Carolina mountains. As more CAA descends into the CWA, temperatures will steadily decline and the first widespread freeze and frost event is expected. Monday night temperatures dip below freezing in the mountains and bottom out in the 20s, with mixed 30s and 40s for the Piedmont. Even colder temperatures are forecasted for the entire region Tuesday and Wednesday night, with widespread 20s and 30s. A freeze watch is likely later today for Monday night. Frost is not expected Monday night as higher winds should prevent it from forming. However, more widespread frost is anticipated. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 230 AM Sunday: Continuing with the short term forecast, freezing temperatures are expected to again be widespread through the CWA, ranging from the 20s to 30s. Widespread frost is expected Wednesday night throughout the majority of the area as colder temperatures settle into the region. Thursday night temperatures will begin to rebound, but frost is likely in the northeastern portion of the CWA. As the upper trough and associated low across the Northeast begins to lift, surface winds returns to a southwesterly flow on Thursday and allows for warmer air to move into the area. High pressure will build back into the region through the rest of the forecast period. Dry conditions will persist as GFS and ECMWF model guidance suggest deep subsidence aloft and minimal PWAT values. Daytime temperatures should start to rise back to near climo and be indicative of the fall weather season. Overnight temperatures will not warm as quickly, however will rise above freezing for the remainder of the forecast period. As for any fire weather concerns, RH values will continue to be lower, teetering in the 30s, in the SE portion of the CWA. Despite the RH values, light winds throughout the week should keep any critical fire weather thresholds from being met. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: VFR conditions will generally continue through the period with mainly mid and high-level clouds increasing from the west today and lowering through the VFR range this evening. Cannot rule out some brief valley fog around daybreak this morning, but increasing high clouds will limit the potential. Surface winds will remain generally locked in from the SW today through tonight, except for mostly NW into the French Broad Valley at KAVL. Low end gusts will be possible once again today, especially in the Upstate where mixing may be a touch deeper. Shower chances will increase from the northwest late today into tonight with the approaching, vigorous cold front. Will confine any PROB30 mentions for now to the NC TAF sites for the last few hours of the current period. Cannot rule out some thunder at the western NC sites, but with low confidence at present. Fog may pose a problem late tonight across the mountains and at KAVL. Outlook: Showers will move east on Monday, with breezy conditions and rapid drying post fropa. Cool and dry high pressure will build into the region through the week. 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...CP NEAR TERM...HG SHORT TERM...CP LONG TERM...CP AVIATION...HG