742 FXUS63 KJKL 211450 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 1050 AM EDT Sat Aug 21 2021 .UPDATE... Issued at 1050 AM EDT SAT AUG 21 2021 The forecast remains largely on track this morning. Fog has dissipated across the area leaving eastern Kentucky under mostly clear skies. Hourly grids have been updated based on latest observation trends. UPDATE Issued at 710 AM EDT SAT AUG 21 2021 Issued an SPS earlier this morning in coordination with surrounding offices for dense fog in the valleys. Fog should burn off by around 9 or 10 AM and then mostly clear to partly cloudy conditions expected late this morning through the afternoon. Updates sent to NDFD and web servers. && .SHORT TERM...(Today through Sunday) Issued at 315 AM EDT SAT AUG 21 2021 Latest analysis shows an upper level low just to our east over WV and upper level ridging to our west over the mid west US. Additional upper level lows are over the northern plains and pacific NW. At the surface, high pressure is over the eastern Great Lakes, and there is a stationary boundary that stretches from the SE states up through central TN and western KY. Locally, patchy valley fog has developed early this morning, but is not nearly as widespread as it was yesterday morning. Fog should be quick to dissipate after sunrise this morning in most locations. A disturbance is expected to break off from the upper level trough in the northern plains today and ride along the stationary front through the day. Most of the precip will remain well to our SW but there is a low chance (under 15%) of an isolated shower/storm sneaking into our SW counties late this afternoon into early this evening. Most of the region will remain dry today with mostly sunny skies early becoming partly cloudy this afternoon. Afternoon high temps will be in the mid to upper 80s. Mostly clear skies tonight although some cloud cover may continue over the far S/SW of the area overnight. Some patchy river valley fog develops towards morning. Overnight low temps will be in the middle 60s. On Sunday the upper level low moves further east into the Mid Atlantic, and a surface cold front associated with a system well north of the upper Great Lakes approaches the area from the west but will likely only make it to southern IN/IL by late in the day. Some widely scattered showers/storms are expected Sunday, mainly during the late afternoon into early evening hours. Afternoon high temps will be in the upper 80s. .LONG TERM...(Sunday night through Friday) Issued at 345 AM EDT SAT AUG 21 2021 The extended period will begin with a broad upper level trough and closed low shifting out of the Mid Atlantic and into the upper East Coast. Current Tropical Storm Henri, expected to be Hurricane Henri, will be making landfall at the start of the period along the coast of New England. To the west, a large dome of upper level ridging sits along Eastern Texas, encompassing much of the Southern Plains and into the Lower Mississippi Valley. This will shift east, increasing heights through Monday across Eastern Kentucky and allowing for both a mostly dry day as well as a warm one. A surface high will continue to sit across the Appalachians as a parent low in Central-Southern Canada works east through the mid and latter part of the week. Along with the low will be a cold front, extended down and through the Mid-Plains Wednesday and through the Ohio Valley by the end of the period. Guidance is in fairly good agreement early in the period. The one exception is the ECMWF which suggests some rainfall is possible Monday across the area, particularly in the higher terrain. Given the downward trend in recent runs, and the agreement among the other operational guidance, have removed any measurable PoPs in this area. With the ridge and rising heights, westerly flow, very low measurable PoPs suggested by the blend, and limited moisture indicated by time-heights, felt fairly confident in this change. Rain chances into Tuesday again look slim (isolated), with the best opportunity along the northwest. As winds shift to be more out of the south midweek and a cold front approaches from the west, PoPs will be on the increase, with the best opportunity Thursday as the front is draped across the Ohio Valley. Showers and storms will be best during peak heating and decreasing with the loss of instability toward nightfall. Sensible weather will feature very summer-like conditions with mainly diurnally driven PoPs Tuesday and onward. Temperatures will generally run 5+ degrees above average through Wednesday, before a cold front looks to bring more average highs late week. With the increased humidity combined with warm temperatures, look for heat indices in the mid and upper 90s through midweek. As with the highs, low will be on the warmer side of the norm, in the mid and upper 60s through the period. Ridge/valley splits will be likely the first half of the period, given the clearer skies and calm winds, which could lead to some of the more sheltered valleys bottoming out towards the lower 60s. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) ISSUED AT 715 AM EDT SAT AUG 21 2021 LIFR conditions the first hour or so of the 12Z TAF period due to dense fog, then VFR conditions are expected from late this morning through the rest of the day. Additional patchy fog overnight into early Sunday morning may result in more flight restrictions. Winds will be light and variable through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...BATZ SHORT TERM...CMF LONG TERM...BB AVIATION...CMF