752 FXUS63 KJKL 012120 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 420 PM EST Tue Dec 1 2020 .SHORT TERM...(This evening through Wednesday night) Issued at 350 PM EST TUE DEC 1 2020 A highly amplified long wave pattern is currently in place across the CONUS. A deep upper level low is spiraling across the eastern portion of the Lower Great Lakes, with troughing extending southward along and east of the Appalachians. Ridging is noted between the Plains and Mississippi Valley, while another trough is aligned from south central Canada down through the Desert Southwest. At the surface, low pressure is migrating across southeastern Quebec. High pressure is centered across the Lower Mississippi Valley, with ridging extending northward. Low pressure is also consolidated near the Texas Panhandle with troughing positioned northward into south central Canada. A few flurries are still lingering across portions of Eastern Kentucky this afternoon, in a cold post-frontal air mass in place, where mostly cloudy skies still reign. Temperatures across most locations have made it back into the lower 30s, with the exception of the higher terrain in far southeastern Kentucky. Black Mountain has managed to stay in the upper teens throughout the day. The models are in excellent agreement through the short term period, maintaining the highly amplified flow pattern aloft. The cutoff low near the Lower Great Lakes will continue to pull away and deepen across Quebec. Meanwhile, a new cutoff low will emerge towards the Southern Plains, with the Mississippi Valley ridge dampening and becoming more consolidated to the Ohio and Tennessee valleys with time. At the surface, high pressure will gradually settle in across the Ohio and Tennessee valleys through the period, with the southern Plains low pressure system nudging east with time, settling near the lower Mississippi Valley by early Thursday morning. Below normal temperatures and mainly dry weather will be seen across Eastern Kentucky through the short term. Clouds and a few flurries will gradually relent from west to east through this evening. As winds diminish, some of the valleys that have maintained a decent snowpack today could see mid teens for lows potentially. Most other locations will see lows in the upper teens to lower 20s. Sunny skies will prevail on Tuesday, with temperatures rebounding into the low to mid 40s. Did stay on the cooler side of guidance here, given the cold start and some snow to melt off. Wednesday night should be chilly once again, as valleys decouple quickly at sunset, although some high clouds will be on the increase from the southwest late. Temperatures will range from the upper teens to lower 20s in the valleys, to the mid 20s on the ridges. .LONG TERM...(Thursday through Tuesday) Issued at 420 PM EST TUE DEC 1 2020 Continued cool and unsettled weather is expected through the long-term. However, plenty of uncertainty lingers through the time period as the models and ensembles are still struggling with the evolution of our high-amplitude, blocky weather pattern. While the models are generally in broad agreement with regard to the upper-level features, the timing and location of the features continue to vary from model-to-model and run-to-run. However, there does seem to be some convergence of the UKMET, ICON, Canadian, and GEFS toward at least some version of the latest operational GFS. Given the apparent shift toward that solution, the PoPs, sky cover, and, to a small degree, the temperatures were nudged toward the Canadian and GFS solutions from late Thursday through early Sunday. Thereafter, the NBM guidance was largely unaltered through the remainder of the forecast period. At the beginning of the period, upper level ridging over the Southeast US will be connected, via a col, to another ridge over the northern Great Plains. Meanwhile, a deep upper level low will be spinning over eastern Canada with troughing extending toward another cutoff low over the Southern Plains. From Thursday- Sunday, this cutoff low will pass through the Southeast US and eventually phase with the low over Eastern Canada. The latest ECWMF and its ensembles are much faster with the phasing and quickly develops an intense nor-easter well to our east. Meanwhile, the GFS and the other models are much slower and weaker with this system, keeping impacts over our region for a longer duration. Once that system lifts away, another sharpening trough and associated cold front will probably drop in from the north early next week. In terms of sensible weather, a frosty, cold start is expected Thursday morning, but a mild southwest return flow and early day sunshine should boost temps back into the 45-55 degree range by the afternoon. High clouds are expected to increase, thicken, and lower through the afternoon with some rain showers developing from the southwest late. All precipitation is expected to remain in liquid form Thursday night, given the WAA and above freezing temperatures below 800mb. Sensible weather on Friday and Saturday will hinge on how quickly this system comes together. In the ECMWF solution, periods of showers on Friday would probably mix with and taper off to a few blustery snow showers Friday night as a bombing coastal low races toward New England. The other models feature a slower-moving developing low over the Appalachians, which keeps rain across the area Friday and Saturday, possibly leading to hydro issues before precipitation tapers to a few flurries Saturday night. In either case, temperatures in the 40s to near 50 on Friday should trend downward through the weekend. A cold front will probably bring additional rain or snow showers late Sunday with upslope flurries lingering into Monday or beyond. Temperatures on Sunday will probably reach well into the 40s, but might be hard-pressed to do so on Monday. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 115 PM EST TUE DEC 1 2020 MVFR ceilings will gradually improve to low end VFR from west to east through early this evening, before the clouds scatter out. VFR conditions will then prevail through the rest of the period, as high pressure builds in across the area. West to west southwest winds of around 10 kts, with gusts of 15 to 20 kts at times, will continue through dusk, before becoming light and variable. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GEOGERIAN LONG TERM...GEERTSON AVIATION...GEOGERIAN