448 FXUS63 KLMK 220258 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 958 PM EST Sun Feb 21 2021 .Forecast Update... Issued at 950 PM EST Sun Feb 21 2021 Leading edge of precip is just on the doorstep of our Indiana counties, and will continue its progress to the east and south over the next few hrs. Other than some minor adjustments to timing in the hi-res products, no changes are planned at this time. && .Short Term...(This evening through Monday) Issued at 225 PM EST Sun Feb 21 2021 A mid-level wave is centered over Iowa this afternoon with troughing extending southwest into New Mexico. 1009 mb sfc low pressure is analyzed near Des Moines, moving northeast. 1036 mb sfc is centered over the VA/NC coast. A tight pressure gradient in the sfc pattern is noted across Missouri and Illinois, where strong southerly winds are resulting in robust WAA in the low to mid levels. The sfc cold front extends south through eastern KS/OK. A band of deeper low to mid level moisture encompasses most of Missouri and Arkansas this afternoon. Over central KY and southern IN, still just have SCT-BKN cirrus over northern KY and southern IN. Southern KY is enjoying plenty of sunshine, where temperatures have surged into the upper 40s to around 50. Meanwhile, temperatures north of I-64 are stuck in the mid 30s to lower 40s. The upper level trough will translate eastward across KY and southern IN overnight into Monday, bringing increasing southwesterly winds at every level. An impressive 50-60 kt SW LLJ at 850 mb moves overhead, with even a narrow corridor of winds near 65 kt at that level. This would be a lot more concerning if the boundary layer was warmer! Fortunately, lapse rates are quite poor and MUCAPE is nil. Still, expect breezy conditions to accompany rain as the cold front sweeps through the forecast area late tonight into Monday morning. Widespread light rain arrives in southern IN and KY counties near and west of I-65 between 8pm-Midnight EST. Areas east of I-65 will likely see rain develop between Midnight-3am EST. Rain chances will then diminish from west to east across central KY and southern IN between 5-11am EST Monday. Just after the main precip shield exits, lingering low level moisture could be enough for a few sprinkles through midday (possibly a flurry or two as well). Tonight, temps will hold steady in the upper 30s to mid 40s until fropa. Temps quickly drop through the 30s Mon morning and should not recover much on Monday. Temps should be in the mid to upper 30s for a lot of the day given that low level thicknesses drop during the daylight hours. Expect breezy westerly winds and mostly cloudy skies. .Long Term...(Monday night through Sunday) Issued at 315 PM EST Sun Feb 21 2021 The start of the long term features a mid-level short wave working across the Great Lakes as high pressure across the northern Gulf of Mexico builds and expands east and northward. The combination will allow clouds to linger Monday evening and gradually clear overnight with breezy southwest winds between 10 to 15 mph and gusts approaching 20 mph. Overnight lows drop to near or just below freezing. With the influence of high pressure on Tuesday it will be a nice day and more sunshine. Thanks to the southerly flow, sunshine and ridging aloft, temperatures in the afternoon will rise into the low 50s. Surface high will be located off the southeast coast of the US on Wednesday as the upper-level flow becomes more zonal. Temperatures will be the warmest in some time reaching the low to mid 50s across most of the area, with some of our southern counties approaching 60 degrees. The next system Wednesday evening is looking a lot weaker. As a weak cold front moves through Wednesday night, there is just a low chance of precipitation and light QPF. Behind the front temperatures will cool slightly back into the 40s for Thursday and Friday afternoon with lows in the 30s Thursday morning and mid 20s Friday morning. With dry and fair weather expected for both days. A lot of certainty remains heading into the weekend and early next week. Models hint at a couple of systems moving through Saturday through early next week but differ on timing and location which will have impacts on the final outcome. So keeping precipitation in the forecast through the weekend. && .Aviation...(00Z TAF Issuance) Issued at 635 PM EST Sun Feb 21 2021 VFR conditions into the evening, but southerly low-level jetting ahead of the front will cause low-level wind shear with speeds hitting 50+ kt at 2000 feet. Look for strato-cu ceilings by mid to late evening, but staying VFR until fropa after midnight. Band of light to moderate rain will take a while to restrict any cig/vis, with the main restriction being MVFR ceilings approaching IFR thresholds. Precip shield exits by daybreak but low-end IFR ceilings persist. West winds through the day will stay up around 12 kt with fairly consistent gusts near 20 kt. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...RAS Short Term...EBW Long Term...BTN Aviation...RAS