676 FXUS63 KJKL 090000 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 800 PM EDT Fri Oct 8 2021 .UPDATE... Issued at 745 PM EDT FRI OCT 8 2021 The thunder threat seems to have waned over eastern Kentucky with loss of sunshine and instability falling. Therefore have updated the forecast to fine tune the PoPs and remove thunder along with adding the latest obs and trends for the T/Td grids. These updates have been sent to NDFD and web servers. The HWO, ZFP, and SAFs were also updated with a beefing up of the dense fog potential highlighted. && .SHORT TERM...(This evening through Saturday night) Issued at 500 PM EDT FRI OCT 8 2021 20Z sfc analysis shows broad low pressure west of the area while high pressure is found to the east. This has left eastern Kentucky in a moist and warm air mass with enough instability around to support convection and a few thunderstorms. The lack of a sfc feature as a trigger has kept the activity rather scattered and mainly in the northeast today but relative high PWATs will mean a small threat for heavy rains from the stronger showers or any thunderstorm. Temperatures are topping out in the mid to upper 70s most places, again this afternoon, while dewpoints are generally in the mid 60s, amid light winds. The models have come in to better agreement aloft through the short term portion of the forecast. They all depict the weakening upper low passing out of the Ohio Valley into the Great Lakes while ridging starts to spread northeast from the Lone Star State. The mid level energy and lower heights exit the area tonight with heights rebounding quickly as the ridge noses in from the southwest. This ridge then elongates over Kentucky on Saturday night - pushing into eastern Ohio by dawn Sunday. Given the small model spread have again favored the blended NBM solution with some terrain adjustments and near term inclusion of CAMs consensus guidance. Sensible weather will feature the remaining northeast convection fading out into the early evening. This then sets the stage for a still humid and mild night but one more prone to the formation of dense fog in the valleys - spreading elsewhere late. This will also mean more terrain distinctions to temperatures tonight in the form of a small to moderate ridge and valley temperature difference into Saturday morning. High pressure will move into the area for Saturday but be slow to push the whole of the moisture out of the area, enough so that showers and even a stray thunderstorm will remain possible in far eastern parts of the area that afternoon and early evening. The drier air moving deeper into the area by late Saturday means another setup for ridge to valley temp splits occurs that night along with anticipated areas of valley fog into Sunday morning. Did make some decent terrain based adjustments to the NBM temps each night. As for PoPs, basically lingered them back to the west of the NBM into this evening - in line with the current radar and near term CAMs. .LONG TERM...(Sunday through Friday) Issued at 329 PM EDT FRI OCT 8 2021 The extended will begin with a departing upper level shortwave just north of the Great Lakes Region and into Southeastern Canada. In its wake, ridging will slide into the area from our southwest. With the rising heights, dry air will return along with warming temperatures through the end of the weekend and into the early work week. Along the Dakotas is another upper level shortwave with a second positioned along the Southern Rockies. Both will push northeast through the early week with a trailing surface cold front along the southern stream wave, which looks to wash out near the Commonwealth towards mid week. Operational guidance is in better agreement today with the ECMWF and GFS on board with limited precipitation chances Tuesday morning and through the afternoon (from west to east). Given the lack of forcing, moisture, and quick progression north and east, have continued to only keep in slight chance PoPs. By Wednesday, a deep trough and subsequent surface low will develop across the Rockies. As with previous waves, guidance too suggests this to progress northeastward as a surface high and upper level ridge sit across the southeastern CONUS. There is discrepancies, however, as the GFS is the most progressive in movement with this low. Ensemble cluster analysis depicts over half of the members suggesting a deeper and slower moving upper level trough. Either way, this could bring us a shot of temps closer to average along with increasing PoPs by the end of next week and into the weekend. Better details will emerge with time, but ridging looks to break down and shift east. Generally speaking, Eastern Kentucky will steer on the drier side through much of the period. Slight chance PoPs in association with a weak front will be possible Tuesday, otherwise ridging will dominate much of the southeast through Wednesday. An advancing low and deep upper level trough out of the Central Plains, along with a cold front, will bring a return of unsettled weather at the end of the period. Temperatures will continue to be warmer than average, topping out in the upper 70s and lower 80s and overnight lows in the mid 50s to low 60s. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 800 PM EDT FRI OCT 8 2021 Prevailing VFR will hold until between 05 and 07Z most sites with fog starting to impact the terminals. Anticipate JKL falling to MVFR visibilities for a time and the rest of the airports likely down to IFR - or worse - for a time late tonight. This fog and any low CIGs will clear out by 14Z with VFR conditions through the day. Winds will be light and variable during the forecast period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...BB AVIATION...GREIF