557 FXUS63 KJKL 190620 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 220 AM EDT Sat Sep 19 2020 .UPDATE... Issued at 155 AM EDT SAT SEP 19 2020 The current forecast is right on track so have mainly updated to include the latest obs and trends for the t/Td grids. Also touched up the river valley fog in the weather grids through dawn. These updates have been sent to the NDFD and web servers. UPDATE Issued at 1143 PM EDT FRI SEP 18 2020 Besides a few small areas of stratocu, as well as some high clouds streaming in aloft across the far south and southeast, skies have cleared out across most locations. Temperatures are running from the low to mid 50s across the area. Some areas of fog have also developed across portions of the Big Sandy and Kentucky River basins, as seen on the Nighttime Microphysics satellite channel. In general, the forecast remains on track. Did make a few tweaks to the temperatures based on the latest trends in observations. Also allowed for a bit more valley fog early on, given the satellite trends. Updates have been sent. UPDATE Issued at 754 PM EDT FRI SEP 18 2020 Stratocu is starting to relent across eastern Kentucky, with the latest satellite trends showing dissipation from west to east with time. Did freshen up the sky cover to reflect the latest trends. Also adjusted some of the low temperatures, allowing for somewhat milder readings to the south, as low level flow gradually veers to the northeast overnight. Updates have been sent. && .SHORT TERM...(This evening through Saturday night) Issued at 337 PM EDT FRI SEP 18 2020 A fairly benign forecast is on tap. After the passage of a cold front during the previous overnight, a much drier and cooler airmass is taking hold from our NW. That being said, lingering moisture from Sally became trapped in the form of low (MVFR) clouds, which has stuck around for a good portion of the day under the cooler northerly flow. As drier air has continued to work in throughout the day, these clouds have slowly eroded away from NW to SE. However, there has been enough lingering moisture in the air and daytime mixing, that as this low cloud deck dissipates and clears out, diurnally driven VFR CU has redeveloped in its place. These CU, and remaining low level clouds, should dissipate during the evening, giving way to mostly clear skies overnight. Breezy conditions have also been on tap behind the cold front, and should also diminish as we head into the evening and lose mixing. Generally clear, calm, and abnormally cool conditions are on tap for tonight. With light northerly flow expected to continue, the lowest diurnal drop may actually be in our western valleys, so tried to account for this in the forecast. Can't rule out some fog development once more, especially in the deeper river valleys and near bodies of water. Surface high pressure will pass to our NE during the day Saturday, with mostly clear conditions expected to continue. With continued NE flow, temperatures will once again top off in the upper 60s to low 70s across the CWA. Not much additional information to add for Saturday night. With high pressure still in control to our NE, another night of dissipating NE winds and clear skies is on tap, along with temps dropping back into the 40s. These cooler temps combined with the sinking air could lead to some fog development in the deeper river valleys and near bodies of water. .LONG TERM...(Sunday through Friday) Issued at 422 PM EDT FRI SEP 18 2020 At the beginning of the forecast period on Sunday, the upper level trough in place begins to exit eastward. Higher heights begin to build in from the west through Monday, and remain through a good portion of the forecast period, before a trough moving east across the Great Lakes causes heights to fall across the Ohio Valley Thursday into Friday. Down at the surface, high pressure dominates, sitting to our northeast and helping to drive in cooler air. By the middle of the week, the high will have shifted south and then sit roughly centered over the state by the middle of the week, only moving slightly through the next couple of days. The main focus at the very end of the period revolves around what happens with now tropical depression 22, and how quickly it gets picked up and pushed north. Though there is still considerable uncertainty and spread among solutions, with most holding off on bringing impacts to our area until after the end of the period. So, kept with the NBM solution of keeping things dry. In terms of sensible weather, the forecast period looks quite pleasant and particularly fall-like, especially early in the week. High temperatures will hover around low 70s through the first half of the week and lows will sink into the 40s. Temperatures will gradually start to rise moving through the rest of the week under the influence of the rising heights aloft, eventually reaching highs in the upper 70s by the end of the period. The dominant high pressure at the surface will help to keep things dry through the week. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 220 AM EDT SAT SEP 19 2020 High pressure, centered to our north, will allow for mainly VFR conditions through the period. Some patchy MVFR or worse fog may be seen within the deeper river valleys towards dawn, particularly across southeastern Kentucky, where the low level drier air has been slower to move in. Few to scattered stratocu of 3-5K feet agl will be found through southeast parts of the area into the day. North to northeast winds will average around 5 kts through Saturday. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...JMW LONG TERM...HAS AVIATION...GEOGERIAN/GREIF