818 FXUS63 KLMK 301116 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 616 AM EST Mon Nov 30 2020 .Forecast Update... Issued at 610 AM EST Mon Nov 30 2020 Upper wave has kicked well into eastern Kentucky, with cooler air aloft spilling into the lower Ohio Valley behind it. We have seen an initial corridor of colder air at the surface from south-central Kentucky up into the Bluegrass region, and that has cooled just enough to allow for intense enough snowfall to accumulate on grassy and elevated surfaces. Other than that, the forecast remains well on track, and the Winter Weather Advisory for late afternoon into tonight will not be modified. The ongoing snow will be covered in a Special Weather Statement, as any impacts are expected to be brief and limited. Pavement temps are still in the 40s, so even where there is some slushy snow (such as bridges/overpasses) it will melt fairly quickly once the snowfall lightens up. && .Short Term...(Today and tonight) Issued at 330 AM EST Mon Nov 30 2020 ...FIRST ACCUMULATING SNOW EXPECTED TONIGHT... Upper wave lifting through the Tennessee Valley, with mid-level frontogenesis focusing a band of moderate precip mainly affecting Middle Tennessee and central Kentucky. It's almost entirely rain so far, but we are seeing a slot of colder temps, generally 33-35F, punching up the I-65 corridor into south central Kentucky. In the very near term, we'll be watching the intensity of the precip shield lifting out of Middle Tennessee as it meets the incoming colder air, as that could focus a band of slushy snow accumulations during the morning commute. Right now the best chance for that appears to be setting up from the Lake Cumberland area to just south of Lexington and Frankfort. However, with the precip in TN showing a weakening trend, confidence is limited enough that we will only be able to do short-fuse messaging as we actually see a band of accumulating snow develop. Look for a rain/snow mix for a lot of the day under the upper cold pool with plenty of wraparound moisture, and some localized Lake Michigan enhancement. Temperatures remain quite flat in the mid/upper 30s, just warm enough to prevent any daytime accumulation even with intermittent changes to all snow. Precip will taper from west to east late in the afternoon as wraparound moisture departs. Temps will drop below freezing just after sunset, with snow showers continuing east of a line from roughly Madison, IN to Lake Cumberland. This area could pick up around 1 inch of accumulation as surface temps continue to drop, resulting in impacts to travel. Current advisory matches up pretty well with the 50-60% probability of 1 inch accumulation and we can't rule out localized 2 inch amounts across the Bluegrass region in KY, where we could see better enhancement from the Lake Michigan plume. Winter Weather Advisory will remain as-is. It's worth noting that the Advisory runs through 7 AM Tuesday, but with temps expected to be in the mid 20s at that time, travel impacts could linger through the Tuesday morning commute even after the snow ends. .Long Term...(Tuesday through Sunday) Issued at 300 AM EST Mon Nov 30 2020 Tuesday looks cold and breezy to begin the long term, with low clouds lingering east of I-65 at sunrise. Portions of the Bluegrass region could see flurries linger into Tue morning. Though moisture depth will be much shallower, the saturated layer does reach up to - 10 C during the morning hours. Areas west of I-65 should wake up to more sunshine. The clearing line will gradually push east through the day. Thanks to cold air and breezy winds, wind chills will begin the day in the teens and will only make it into the 20s and low 30s during the afternoon. Shortwave ridging and sfc high pressure will exert their influence on our weather through Wednesday. Tue night will be cold and clear with lows in the low to mid 20s. Upper teens in typically cooler locations, such as valleys, seems like a decent bet. Fair weather continues Wednesday with highs in the 40s. There remains good agreement on a closed upper system and weak sfc reflection rotating across KY and southern IN Wednesday night through Thursday night, bringing light precipitation to the region. Timing and QPF discrepancies linger, however, with GFS/CMC solutions notably faster than the ECMWF. There does appear to be some diurnal variability in p-type, with plain rain likely winning out during the daytime on Thursday. But decided to lean on the relatively low PoPs/QPF from NBM for now. Lows are likely to be below freezing Thu morning with highs in the 40s. Fri morning should be a touch warmer with lows in the low to mid 30s. Model consistency suffers by the weekend, though it does appear a notable trough may dive southeast over the Upper Ohio Valley late in the weekend. Without a meaningful signal, going to stick with a dry forecast through the weekend. Chilly temperatures are likely to continue during this time. && .Aviation...(12Z TAF Issuance) Issued at 610 AM EST Mon Nov 30 2020 Tongue of colder air has pushed into LEX and helped transition precip to a decent snow, resulting in LIFR conditions and could accumulate on elevated surfaces in the next couple of hours. SDF, BWG, and HNB are all MVFR and still showing NW winds less than 10 kt. Leading edge of some stronger NW winds and cold advection just getting into HNB and will continue to press eastward through the morning. This will also help the switch to all snow, and could bring brief IFR ceiling and vis. Wind speeds around 15 kt with gusts near 25 kt could result in crosswind issues, especially at LEX but possibly SDF as well. Precip tapers off around sunset or just after at SDF, HNB, and BWG, with ceilings lifting to VFR. LEX will struggle through the evening with IFR cig/vis in continued snow showers, and temps dropping below freezing. Crosswinds will continue with gusts near 20 kt. Cig/vis will finally lift after midnight in LEX. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...Winter Weather Advisory from 4 PM this afternoon to 7 AM EST Tuesday for INZ079. KY...Winter Weather Advisory from 4 PM EST /3 PM CST/ this afternoon to 7 AM EST /6 AM CST/ Tuesday for KYZ032>037-039>043- 047>049-055>057-066-067-078-082. && $$ Update...RAS Short Term...RAS Long Term...EBW Aviation...RAS