574 FXUS63 KJKL 071425 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1025 AM EDT Fri Oct 7 2022 .UPDATE... Issued at 1025 AM EDT FRI OCT 7 2022 14Z sfc analysis shows a cold front pushing into eastern Kentucky from the northwest. This is noted by the wind shift to the north and a pick up in speed to between 10 and 15 mph and a band of thicker/lower clouds. Temperatures varying across this boundary will become more clear shortly with the cooler post frontal air compared to diurnal warming still out ahead of it. Readings are mainly in the mid to upper 50s currently, though some low 50s are still holding on in a few of the more sheltered valleys. Meanwhile, amid light and variable winds ahead of the dry front, dewpoints are mainly in the lower 50s. Have updated the forecast to mostly fine tune the sky cover into the afternoon and add in the latest obs and trends for the T/Td grids. These updates have been sent to the NDFD and web servers. UPDATE Issued at 750 AM EDT FRI OCT 7 2022 The forecast generally remains on track. Did freshen up the diurnal temperature curve through this morning, accounting for the latest trends in the observations. The cold front has entered the I-64 corridor, and this will continue to shift southeast through the day. && .SHORT TERM...(Today through Saturday) Issued at 524 AM EDT FRI OCT 7 2022 The latest upper level map features a seasonably strong ridge positioned from the West Coast through the Gulf of Alaska, with another branch spread through the Northwest Territories. Further east, broad troughing/cyclonic flow encompasses most locations east of the Continental Divide, with several short wave troughs moving through the flow. At the surface, high pressure has retreated to the Gulf states. Low pressure is seen across southern Ontario, with a cold front aligned southwest through the Ohio Valley and middle Mississippi Valley, before becoming more stationary across the southern Plains and Rockies. Behind this boundary, a nearly 1040 mb high is centered across eastern North Dakota. Mostly clear skies currently reign across eastern Kentucky, with fog forming in the river valleys once again. Temperatures range from the low to mid 40s at the cooler valley sites, to the low to mid 50s atop the ridges. The models remain in good agreement through the short term, with a more vigorous short wave moving out of Nunavut to reinforce the trough/cyclonic flow east of the Rockies through the end of the short term period. At the surface, a cold front will sag southeast of the Ohio Valley today, with Canadian high pressure settling south southeast through the Plains and into the Ohio Valley. This will bring a much more fall-like air mass into eastern Kentucky by tonight and Saturday, with areas of frost expected by early Saturday morning for portions of the forecast area. The cold front will push southeast across our area through this morning/early afternoon. The passage of the boundary will mainly result in an increase in cloud cover, although a sprinkle or very light transient rain shower might be possible across southeastern Kentucky by late this afternoon/early this evening. Given that the 6 hour probabilities of locations receiving greater than 0.01 inches have been trending down in the HREF since the 00z run from October 6th, will keep a persistent dry forecast going. Highs today will range from the mid 60s north of I-64, to the low to mid 70s bordering Tennessee and Virginia. Clouds will gradually clear out tonight, although these will be slower to clear the far southeast until later into the night. Winds will gradually calm with time, with lows ranging from the low to mid 30s northwest, to upper 30s southeast. Patchy fog will likely form within the river valleys, especially southeast, where better low level moisture will linger the longest. Outside of the deeper river valleys, expect areas of frost to form where temperatures dip into the low to mid 30s. As such, have hoisted a Frost Advisory for portions of the area. The frost will burn off between 9 and 10 am, with temperatures only rebounding into the upper 50s to around 60 under mainly clear skies on Saturday. .LONG TERM...(Saturday night through Thursday) Issued at 404 AM EDT FRI OCT 7 2022 Key Points: * Freeze Watch introduced area-wide Saturday night, as valley lows fall into the upper 20s to around 30 degrees. * A cool and dry air mass will be in place to begin the period, with an overall warming trend expected through mid week. * A passing disturbance and cold front will bring a welcomed shot of rainfall the second half of the work week. The period will begin on the backside of a stout cold front, where a Canadian airmass will allow for cool and dry conditions across the Commonwealth. With an expansive high directly above the area, prolonged dry antecedent soil conditions, and calm winds, an ideal set up for effective radiational cooling will be in place overnight Saturday. As such, have blended valley lows closer to the 5th and 10th percentiles, while fine tuning the Bluegrass and SW where the coolest of temperatures will likely be seen. Given the set up, have gone with a Freeze Watch to highlight the potential impacts to sensitive vegetation into Sunday morning. Cool temperatures will continue through the afternoon as well, with mostly sunny skies and highs around 10 degrees below average for this time of the year. Aloft, longwave troughing encompasses much of the eastern half of the USA where an additional positively tilted wave sits near the Four Corners region. Further south, shortwave ridging resides across portions of Texas and the Gulf of Mexico, meandering east with time. Heights will slowly increase Sunday and through the early work week as a result, with a surface high settling across the Appalachians from the Lower Mississippi Valley. Toward mid and late week, model trends begin to diverge. A closed upper level Canadian low will dive SE from the Northwest Territories, supporting another strong cold front. Operational runs are struggling to grasp the location/path of the low, with the Canadian much further north than its counterparts, and thus, suggesting a much drier and slower solution. Comparing these deterministic runs with ensemble data, a better picture is painted. The best Day 6 agreement, around 30% for the GEFS, Euro, and Canadian members, is of a closed low across the southern edge of the Hudson Bay. Differences in timing/progression can be expected this far out, so have veered toward the blend for now. Nonetheless, a decent shot of rainfall is in the forecast with chance PoPs (30- 40%) Wednesday night and through Thursday. There is potential for some thunder given the instability, but have held off for now until the timing of the system becomes clearer. The biggest frost/freeze concern will be into Sunday morning, but will mention frost potential again overnight Sunday and into Monday, where lows find the low to upper 30s. This is primarily for valley locations each of the two nights (Saturday & Sunday), where ridge temps are a bit more elevated. Temperatures then gradually tick upward through midweek, before another chilly blast of air finds the region late week and into next weekend post front. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) ISSUED AT 750 AM EDT FRI OCT 7 2022 Mostly VFR conditions will prevail through the period. Some patchy IFR fog will burn off through around 13z this morning. A passing cold front will then bring scattered to broken lower end VFR clouds to the area from northwest to southeast during the day in its wake. Model guidance has trended a bit higher with the ceilings, so will keep out a mention of MVFR. Clouds will then diminish from northwest to southeast late today into this evening. South to southwest winds of around 5 kts or less will veer to the northwest and increase to 5 to 10 kts behind the frontal passage today. Winds will continue to veer to the north northwest by this evening, generally lessening to around 5 kts. && .JKL WATCHES/WARNINGS/ADVISORIES... Frost Advisory from 2 AM to 10 AM EDT Saturday for KYZ044- 050>052-058>060-068-069-079-083-104-106-108-111. Freeze Watch from late Saturday night through Sunday morning for KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120. && $$ UPDATE...GREIF SHORT TERM...GEOGERIAN LONG TERM...BB AVIATION...GEOGERIAN