504 FXUS63 KJKL 070804 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 404 AM EDT Fri Oct 7 2022 .UPDATE... Issued at 1213 AM EDT FRI OCT 7 2022 Beginning to see a bit of valley fog developing on regional satellite. Thus made a quick update to the forecast package to add in a bit of patchy fog into some of the river valleys. Otherwise, forecast continues to run generally on target. Short term trends suggest a bit of drying behind what may be some type of weak boundary passing through the region, with the current scattered mid level clouds that are passing through the area likely associated with this feature. Drying appears to be limited to the thermal belt region, with the river valleys remaining decoupled. No other updated at this time. UPDATE Issued at 945 PM EDT THU OCT 6 2022 Forecast appears on track this evening. Nudged temperatures and dew point grids towards most recent surface conditions. Temperatures were cooling a bit faster than advertised in the forecast package, but generally on track for advertised overnight lows. Freshened up the zone wording. No other changes at this time. UPDATE Issued at 759 PM EDT THU OCT 6 2022 Some mid level AC continues to roll through the region this evening. There has been some virga associated with light radar returns, and even a few reports of some sprinkles reaching the ground. Should see a period of clearing well after midnight as these clouds pass to our northeast and remain clear or several hours through or until about mid-day Friday. A cold front will be pushing through eastern Kentucky,reaching our northwest counties around sunrise and entirely through eastern Kentucky by early to mid afternoon. Winds will veer out of the west-northwest at 5-10 mph behind the front. There will be a band of moisture well behind the surface boundary, similar to an anafront, but not expecting any precipitation, though suspect a few sprinkles would be possible based on time heights and sounding data. && .SHORT TERM...(This evening through Friday night) Issued at 311 PM EDT THU OCT 6 2022 The afternoon surface analysis shows high pressure remains in control of the weather across the Ohio Valley this afternoon. The main feature of interest is an upper level shortwave that continues to push east. This has kept a few passing mid and high level clouds going this afternoon, but outside this dry air at the surface is keeping anything you see on radar to virga or perhaps a brief sprinkle of rain. Overall this is leading to mostly sunny skies and temperatures in the low to mid 70s, but even some upper 70s have been seen in the central part of the state. The next feature of interest upstream is a cold front that is set to push toward the area late tonight into Friday. In the wake of the upper level feature today we could see a few lower clouds push into the area based on the HREF. Overall mostly clear skies are expected with perhaps some gradient setting up late. The mostly clear skies and calm conditions in the valleys will lead to a a decent split of 10 degrees or so from the ridges. This allow temperatures to drop into the low to mid 40s in the valleys and upper 40s to lower 50s on the ridges. The was handled well by leaning toward the fifth and tenth percentiles of the NBM for the sheltered valleys. This cold front will help to usher in a Canadian airmass Friday, as a Canadian high pressure located north of the border this afternoon sinks toward the Middle Mississippi River Valley by Friday afternoon and evening. The remains strong agreement among the various ensemble systems on the high placement and therefore leaned toward the NBM Friday. This will likely lead to a mix of sun and clouds on depending on the speed of the strong cold front. Also, as stated this will bring in a cooler and dry airmass, as winds go from westerly to northwesterly through the day on Friday. Most will top out in the mid to upper 60s with perhaps a few 70s depending on cloud cover and the frontal boundary speed. There is good agreement among the various ensemble and deterministic modeling systems to continue to lean toward the NBM for Friday night. It does look like some moisture becomes trapped in the far east and southeastern parts of Kentucky leading to some relatively lower stratus potential. Overall the surface high will not crest and therefore expect some mixing will remain across parts of the area due to the pressure gradient. This leads to some concern on how much frost we see but will keep it to patchy to areas toward dawn Saturday. Also, leaned a little cooler in the valleys mainly in the southwest and Bluegrass. Did hold back in the far east and southeast given those linger cloud cover potential. This will bring lows into the low to mid 30s in the Bluegrass and Lake Cumberland area and outside this likely more like mid to upper 30s. .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 06Z TAFS through 06Z Friday night) ISSUED AT 146 AM EDT FRI OCT 7 2022 Mostly VFR conditions will prevail through the period. Some patchy IFR fog will dot the deeper river valleys in southeastern Kentucky through the rest of the night, but this should not impact any of the TAF sites. Scattered higher-based cumulus and altocumulus will continue to be seen through the next few hours, before generally dissipating through dawn. A passing cold front will then bring scattered to broken lower end VFR/MVFR clouds to the area from northwest to southeast during the day. Have included a small window of MVFR at KSYM late this morning through early this afternoon. Clouds will then diminish from northwest to southeast late today into this evening, lingering longest across KSJS. 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...RAY SHORT TERM...DJ LONG TERM...BB AVIATION...GEOGERIAN