Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 242345 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 745 PM EDT Sat Mar 24 2018 .UPDATE... Issued at 720 PM EDT SAT MAR 24 2018 Updated the forecast to drop the Advisory counties as temperatures have climbed above freezing there and they are no longer under a threat of accumulating snow or sleet. Did issue an SPS covering the slush and slick spot potential for the roads tonight in those locations. Additionally, fine tuned the convection and thunder threat for the area through the evening with this update. A freshened set of zones and new HWO was issued along with the WSW cancellation statement. The WSWs continue with accumulating snow and related problems likely to continue. The updated grids have been sent to the NDFD and web servers. && .SHORT TERM...(This evening through Sunday night) Issued at 455 PM EDT SAT MAR 24 2018 20z sfc analysis shows a dynamic and complex spring storm system moving through southern Kentucky. This has pumped copious amounts of moisture into the area with its warmer air overrunning a cold dome to the northeast that has been slow to retreat. As a result heavy snow fell through the northeast third of the state overcoming initially warm roads to accumulate and create treacherous driving conditions generally from the Mountain Parkway northeast as well as on the ridges to the southeast. The snow became more convective with time and several good squalls moved through northeast of the snow line dumping inch plus per hour amounts for much of that area. This necessitated pushing the warnings further east just as the advisory had to be extended a tier of counties to the south due to the cold air holding in longer than modeled. As it stands, now the convective element has taken over much of the state with rain and snow showers scattered through the north and showers/thunderstorms found in the south. Cannot rule out thunderstorms developing north of the snow line potentially giving a complete mixed bag of pcpn, including hail, out of any such cell that develops there. Readings currently vary northeast to southwest across the JKL CWA from the low 30s in the cold air to the lower 40s nearer the Tennessee border while dewpoints are not far from temperatures everywhere contributing to patchy fog. East to northeasterly wind flow continues across the area at 10 to 15 kts with occasional higher gusts. The models are similar aloft through the short term portion of the forecast. They all depict a strong, but dampening wave cutting through Kentucky in a larger regime of rising heights that will leave heights similar through the next 12 to 18 hours. This wave turned out to be more dynamic than modeled so far so will continue to favor the stronger NAM12 solution. Northwest flow follows on Sunday as the ridge pushes further east and over Kentucky through Monday morning - where the NAM solution was also favored. Sensible weather will feature a changeable situation with warmer air finally overwhelming the cold through the evening. Convection will accompany this change with elevated instability in place resulting in a concern for storms this evening and early overnight for much of the CWA. Hail will be the main problem from these, but gusty winds and heavy rains will also threaten. This mixed bag of weather will finally settle down after midnight with the snow threat ending as well as the convection. The amount of rainfall from this system will likely lead to rises on the Cumberland and Kentucky River basins, but probably not enough to get to flood at any location as the better rains fell to the north of those headwaters. Cooling temperatures late tonight will also lead to a potential for black ice where roads are wet or slush covered. The sfc low responsible for this storm will not completely clear the area, though, so that a few rain or snow showers may linger into Sunday. Sunday night looks dry, for the most part, with a potential for frost, though thick cloud cover should keep it at bay for most places. Used the CONSShort and ShortBlend grids as a starting point with extra cooling added overnight and on Sunday for the snow covered areas. As for PoPs, lingered them longer on Sunday and then dampened them that night in the southeast. .LONG TERM...(Monday through Saturday) Issued at 512 PM EDT SAT MAR 24 2018 An amplified long wave pattern will remain in place across the CONUS through the middle of next week, before then transitioning to more zonal flow by the start of the next weekend. A ridge will start out across the Mississippi Valley, with a trough across the West. The trough will gradually push east, allowing for a northeast to southwest baroclinic zone to take shape from the Great Lakes down to the Arklatex region. This boundary will then take its time moving across the Mississippi Valley, yielding another extended period of unsettled weather across the Ohio and Tennessee valleys. Dry weather will be short-lived across eastern Kentucky to start the work week, as a warm front lifts northeast across the area by Monday night into early Tuesday morning, bringing the threat of showers to our area. The remnant surface cold front will then slowly push east across the area Tuesday through Thursday, with multiple waves of low pressure riding up along the boundary. This will bring gradually increasing rain chances from northwest to southeast across eastern Kentucky. By Friday, there has been more discontinuity as the final trough axis pushes through the area, so have stayed close to the blended solution, allowing for POPs to hang on a bit longer. Drier weather then returns to start the weekend. Temperatures will trend towards slightly above normal readings through the work week, before cooling down a bit for the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 745 PM EDT SAT MAR 24 2018 Low cigs and vis impacts continue for the TAF sites this evening. Most of them have seen a changeover for good to rain, but we could still see some switching back at SYM and SJS. Conditions will remain LIFR/IFR for the bulk of the night before improving toward dawn from west to east - continuing into Sunday morning. Additionally, the terminals across southern to southeast Kentucky, including SME/LOZ may still see a few bolts of lightning until late evening as some elevated thunderstorms remain possible. Conditions everywhere improve for Sunday with clearing vis and cigs coming up to MVFR at the least. Winds will be generally northeast to east at 5 to 10 kts with occasional gusts up to 15 kts through the remainder of this evening and again during the day Sunday. && .JKL WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 2 AM EDT Sunday for KYZ044-050>052- 060-104-106-107-109-110-119-120. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...GEOGERIAN AVIATION...GREIF is the U.S. government's official web portal to all federal, state and local government web resources and services.