FXUS63 KJKL 231923 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 323 PM EDT Sun Aug 23 2026 .KEY MESSAGES... - Noticeably cooler and less humid air arrives behind a cold front to start the new week. - Chances for a few showers and thunderstorms return around midweek. && .UPDATE... Issued at 1025 AM EDT SUN AUG 23 2026 14Z sfc analysis shows high pressure nudging into Kentucky from the west. This is working to clear the morning valley fog while it brings in slightly drier and cooler air. Currently, temperatures are running in the mid upper 60s to lower 70s. Meanwhile, amid light winds, dewpoints are generally in the low 60s north and in the mid to upper 60s south. Have updated the forecast mainly to add in the latest obs and trends for the T/Td/Sky grids. These minor adjustments have been sent to the NDFD and web servers along with a freshening of the SAFs and zones. && .SHORT TERM...(Today through Monday) Issued at 520 AM EDT SUN AUG 23 2026 Early this morning, an enlongated upper low was centered over sections of the Great Lakes with an upper trough axis southeast into the mid OH Valley and Central to Southern Appalachians to the Carolinas with an upper ridge centered in NM with ridging extending across portions of the western Conus into the Central Conus/Plains. Drier air has been gradually moving into the Lower OH Valley and eastern KY behind a cold front though the drier air has made a bit less progress into the more southern and southeastern locations as a ridge of sfc high pressure builds into the Lower OH valley from the mid and upper MS Valley regions. Rather extensive fog mainly in the valleys has spread into some no valley locations. Some observation sites such as KEKQ, KSME, and KI35 have recently reported dense fog and fog appears on the dense side at some KY Mesonet station locations as well as on a few of the KYTC cameras. With that in mind, have opted to issue an SPS for fog over the next few hours for areas generally south and southeast of the I-64 corridor. Today and tonight, gradual 500 mb height rises are anticipated as the upper low meanders to the eastern Great Lakes and sections of the mid Atlantic states and axis of the upper trough remains east of the Commonwealth. At the same time, the sfc ridge of high pressure will build across the Commonwealth and into sections of the mid OH Valley by late tonight. A dry airmass for this time of year will be ushered into eastern KY with PW per the 00Z HREF expected in the 5th to 20th percentile. This will set the stage for not much in the way of cloud cover today other than diurnally driven cumulus following the lifting and dissipation of the fog through the 9 AM to 10 AM EDT timeframe this morning. Mixing should result in dewpoints dropping a bit below NBM deterministic values. This airmass will also be cooler as well as drier and this should support highs around 5 degrees below normal for the day on Sunday. The pattern should again favor valley fog formation along the rivers, larger creeks, and area lakes tonight. The normally colder locations may drop to as low as 52 or 53 tonight with the drier airmass in place with more in the way of solid mid 50s for valleys where fog forms and ridgetop locations on the order of the upper 50s to near 60. On Monday, 500 mb heights should continue a general upward trend as the axis of the upper trough moves further east of the Lower OH Valley and Appalachians and upper ridging centered in the NM vicinity builds in sections of the Central Conus/Plains and toward the MS Valley. One more shortwaves will be moving around this ridging and near the mid MS Valley area by Monday evening. Highs for Monday should be similar to Sunday with northwest to west northwest flow aloft prevailing. .LONG TERM...(Tuesday through Sunday) Issued at 323 PM EDT SUN AUG 23 2026 The long term period begins Tuesday with a subtropical ridge and closed 500 mb high ranging from 594-597 dm centered over the Four Corners region. Elsewhere, an upper-level trough is modeled across the Great Lakes, Mid-Atlantic, and New England. Across eastern Kentucky, Tuesday will be fair and quiet with dew points in the 50s, and temperatures in the mid 80s feeling a bit less humid compared to previous days. Overnight, light winds and clear skies may aid in patchy valley fog developing in typical favored river valley locations. With valleys possibly decoupling at night, temperatures in the valleys may cool into the mid to upper 50s, while ridgetops cool into the upper 50s to low 60s, Tuesday night. An upper low modeled over southern Manitoba will progress southeast overnight, ending up in the Upper Great Lakes by Wednesday morning. A surface low will also form in the Great Lakes vicinity. Some high and mid-level clouds may work into the area through Wednesday in advance of the approaching system. By Wednesday evening, as a surface cold front extends from the Great Lakes southwestward through the Ohio Valley and Ozarks, isolated to scattered showers and thunderstorms will develop Wednesday night into Thursday, peaking Thursday ahead of the frontal passage. By Friday, the cold front is expected to have passed east of the Commonwealth, with the trough axis shifting east of the forecast area Friday into Saturday, leaving broad troughing across the eastern US. Lingering moisture along the departing trough may support isolated shower and storm chances Friday afternoon along the VA/KY border. Model and ensemble agreement is poor by next weekend. However, deterministic guidance diverges, with one scenario depicting a shortwave progressing through the Central Plains into portions of the Mid-Mississippi and lower Ohio Valleys by Saturday evening into Sunday, which would lead to another round of showers and storms across the area on Sunday. Conversely, an alternate scenario tracks the shortwave farther north into the Ohio Valley. NBM has maintained low-end isolated PoPs for Sunday (15-20%) to reflect this low-confidence scenario. Temperatures should remain slightly above normal for this time of year, in the mid to upper 80s. The CPC 6-10 day outlook supports this thinking. && .AVIATION...(For the 18Z TAFS through 18Z Monday afternoon) ISSUED AT 248 PM EDT SUN AUG 23 2026 Valley fog is forecast for overnight and early Monday. It will bring localized IFR or worse conditions, probably affecting a few TAF sites at times around dawn. Otherwise, VFR conditions are expected through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...GREIF SHORT TERM...JP LONG TERM...GINNICK AVIATION...HAL