008 FXUS63 KLMK 180540 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 1240 AM EST Tue Feb 18 2020 ...Updated Aviation Discussion... .Forecast Update... Issued at 836 PM EST Mon Feb 17 2020 Wind gusts of 30-35 mph have been reported recently in middle Tennessee and extreme southern Kentucky as low pressure over Iowa lifts a warm front northward across the Commonwealth. Have upped wind gusts in the forecast for the next several hours to account for this. Wind gusts should settle down some during the pre-dawn hours late tonight as low level jetting moves off to the northeast. && .Short Term...(This evening through Tuesday) Issued at 250 PM EST Mon Feb 17 2020 After a fairly dry and quiet day across the region, rain chances will begin to increase tonight ahead of an approaching system. Regional radars have shown some light returns throughout the day, but for the most part, these rains have stayed to our north and west. Temperatures today have been unseasonably warm under broad southwesterly flow, with highs this afternoon pushing into the upper 50s to lower 60s. Tonight, expect an area of surface low pressure to develop over the Central Plains and quickly move northeast into the Great Lakes region by Tuesday morning as a shortwave trough pushes across the Upper MS Valley. The attendant cold front will approach from the northwest early Tuesday morning, and then exit off to the southeast Tuesday afternoon. With hi-res model guidance trending towards a slower onset of precipitation, current thinking is that PoPs will begin to increase after sunset over southern IN, and gradually spread eastward across the area by midnight EST. The best chances of rainfall will be overnight, and then expect rain to taper off from northwest to southeast Tuesday afternoon as the cold front moves through the area. Overall, expect rainfall amounts will generally be under a half inch. Lows tonight will remain in the upper 40s to lower 50s as warm, moist southerly flow under a blanket of clouds will prevent temperatures from falling too much. Expect winds to remain out of the south/southwest overnight before beginning to veer to the northwest tomorrow morning and afternoon as the cold front moves through. Sustained speeds of 10-15 mph are likely this evening and again tomorrow afternoon under a tightening pressure gradient. .Long Term...(Tuesday night through Monday) Issued at 250 PM EST Mon Feb 17 2020 Tuesday night high pressure will be building into the region from the northwest...steadily bringing an end to precip chances across our Lake Cumberland region. Cloud cover should linger into the afternoon hours Wednesday as we start scouring out the low-level moisture with dry air aloft. The center of that high will slow down, getting to Iowa Thursday and then across our area Friday night. Expect a fairly dry Arctic airmass in place...nice to for once be on the other extreme side compared to our very wet pattern of the last couple of months. Precipitable waters come down to around a tenth of an inch by Friday...according to the 00Z NAEFS. Temperatures should go below normal Wednesday likely to Saturday morning. As we get to the weekend, there has been a fairly consistent signal for an upper low to move out of the desert southwest and bring in some precip chances starting as early as Sat. night. Model guidance has diverged on how the waves of energy track in and then how far north a surface low tracks. The GFS brings a surface low into the Ohio Valley Monday, whereas the Euro keeps the track more over the TN Valley and then eastern KY and the CMC is much more suppressed. Cold air in place could make for some rain/snow issues should precip make its way this far north for Sunday/Monday...but given model spread, it is much too early to too concerned about this system just yet. && .Aviation...(06Z TAF Issuance) Issued at 1238 AM EST Tue Feb 18 2020 Nighttime satellite shows a vast field of MVFR CIGs moving in from the west while current LVX radar shows light returns across southern Indiana and just upstream of BWG. Regional observations place the cold front currently through central MO. As the front pushes eastward, CIGs will gradually deteriorate to IFR accompanied by light rain and fog. VIS will likely be restricted to MVFR until late morning and improve with the passage of the cold front as winds veer from SW to NW. All sites should go VFR by Tuesday evening, except for LEX where model guidance suggests MVFR CIGs will persist overnight. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...13 Short Term...JML Long Term...RJS Aviation...CG