Area Forecast Discussion
Issued by NWS Jackson, KY

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474 FXUS63 KJKL 231712 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 112 PM EDT Fri Mar 23 2018 .UPDATE... Issued at 1103 AM EDT FRI MAR 23 2018 NDFD has been updated for latest observational trends, but there are no substantial changes to the forecast at this time. A very complex forecast is shaping up for the weekend, with concerns for heavy wet snow in the north, thunderstorms in the south, and maybe even some flood issues. Beginning to see some of the 12Z model data, but not enough yet to begin drawing any conclusions. Some of the forecast soundings in the far north are of concern, with deep nearly isothermal profiles near the freezing mark. If such a sounding verifies that could mean a very heavy wet clinging snow where even 3 or 4 inches could result in power outage problems. However, it also means that just a degree temperature difference can result in a very cold rain. It is likely some adjustments will be made to the advisory area this afternoon, and it is possible at least a few counties may need to upgraded to winter storm warnings. The other concern is rainfall in the southern part of the forecast that could eventually lead to some high water issues. This morning`s river runs are taking Barbourville and Williamsburg into minor flood later this weekend. It is possible a flood watch may be needed for at least part of the area as well. UPDATE Issued at 755 AM EDT FRI MAR 23 2018 Mid clouds have increased across the lower Ohio Valley this morning as mid-high clouds continue to stream toward the northeast out of western Kentucky. Otherwise, expect frost and any lingering fog to mix out within an hour or two as temperatures warm. && .SHORT TERM...
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(Today through Saturday) Issued at 411 AM EDT FRI MAR 23 2018 High pressure will maintain dry weather across eastern Kentucky this morning and afternoon as clouds steadily increase from the southwest. This uptick in cloud cover will be stemming from a shortwave trough and accompanying surface low migrating from the Great Plains into the Midwest. This will bring precipitation across the eastern portion of the Commonwealth this evening through tonight, beginning in the Lake Cumberland region and moving northeast through the night. While warm enough air should filter in to keep precipitation of the liquid variety south and west of roughly a McKee to Harlan line, areas northeast of this line will see a mix with snow and perhaps some periods of sleet. Not expecting freezing rain to be an issue given the presence of ice aloft. However, a tight gradient will likely exist between rain and a mix with snow/sleet as the recent cold dome holds strong across northeast Kentucky with the approaching surface low translating east/southeast through the Ozarks toward the northern reaches of Tennessee. Exactly where the accompanying warm nose and remnant cold air reside will play an integral role in where impactful snowfall amounts occur. Given recent trends, have opted to hoist a Winter Weather Advisory from early tonight through early Saturday night for points north and east of a Mount Sterling to Pikeville line. While storm total snowfall amounts may reach or slightly exceed 4 inches across portions of the Bluegrass and Big Sandy regions, the likelihood of this seems fairly low over a 12 hour timespan early Saturday given surface temperatures right around the freezing mark. The sun angle this time of year and the wet nature of this snow should also prove detrimental to significant accumulations, although a quick burst early Saturday morning could allow for some rapid accumulations. Omega profiles are rather stout above the surface and within the dendritic growth zone, but this latter feature does look to remain fairly high (above 13-14k feet) atop a saturated/isothermal layer just below freezing. Would therefore think that impacts will be more that of advisory level as road surfaces should see decent meltoff, especially after sunrise. The greatest of these impacts will be early Saturday morning and again Saturday evening underneath dark skies. Storm total snow accumulations should generally range from 1 to 4 inches through a 24 hour period from Friday night through Saturday evening, with isolated amounts of 4-5 inches in Fleming and perhaps Bath/Rowan/Elliott Counties. Will assess trends this morning and afternoon in regard to expansion of the advisory or a necessary upgrade to a warning. Additionally, may experience a few rumbles of thunder Saturday afternoon and evening across portions of southeast Kentucky as elevated instability increases. .LONG TERM...(Sunday through Friday) Issued at 111 PM EDT FRI MAR 23 2018 The long term portion of the forecast will feature a deepening upper level trough over the western U.S. early next week, with deep southwest flow becoming established across the OH and TN valleys. By the end of the week the trough will shift east, but with southwest flow across the eastern U.S. continuing. There is good model agreement with the overall upper air pattern though some differences are to be expected with individual short waves ejecting from the upper low that will be over the southwestern part of the United States through the first half of next week. With good model agreement with the overall pattern, the concern for the coming week will be the potential for heavy rain somewhere in the central to eastern U.S. with deep southwest flow becoming established. Current indications are that the heaviest rains will likely affect areas to our west early to mid week as a slow moving front moves into the MS Valley. The front will eventually move across our area during the second half of the week, but it is possible it will stall again at some point near us or just to our east. The greatest threat for heavy rains next week appears to be over western KY and TN. While this is outside our forecast area it is close enough that the coming week will need to be monitored closely. Considering the heaviest rain potential is still 5 days away or so, it is likely the forecast axis of heaviest rains will shift during the coming days. The southwest flow will also result in warming temperatures, with above normal temperatures expected from Tuesday through at least Thursday.
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&& .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) ISSUED AT 755 AM EDT FRI MAR 23 2018 VFR conditions will continue to rule through this afternoon and this evening as clouds gradually thicken and lower ahead of an approaching disturbance. Light rain will begin to impact sites near SME and LOZ this evening, with snow and some periods of sleet impacting sites northeast of a McKee to Harlan line. Conditions will continue to deteriorate overnight with MVFR or worse ceilings overspreading much of eastern Kentucky by dawn. Snow and slippery/slushy tarmacs will be most problematic tonight into Saturday north of a KPBX to KJKL to KLEX line. Winds will largely remain below 10 knots as they veer from northwesterly today to east/northeasterly this evening. && .JKL WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 2 AM Saturday to 2 AM EDT Sunday for KYZ044-050>052-060-104-106-107-109-110-119-120. && $$ UPDATE...SBH SHORT TERM...GUSEMAN LONG TERM...SBH AVIATION...GUSEMAN is the U.S. government's official web portal to all federal, state and local government web resources and services.