


Area Forecast Discussion
Issued by NWS Jackson, KY
Issued by NWS Jackson, KY
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919 FXUS63 KJKL 180613 AAD AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 213 AM EDT Sat Oct 18 2025 .KEY MESSAGES... - Expect one last very warm day on Saturday. A strong cold front will then bring strong to potentially damaging wind gusts as it crosses the area on Sunday morning. - Following the front, expect blustery conditions with gusty showers and falling temperatures on Sunday afternoon. - Another round of strong, gusty winds is expected on Tuesday afternoon as a second cold front moves through. - Much colder air will settle in for next week, creating the potential for frost in sheltered valleys on Tuesday and Wednesday nights. && .UPDATE... Issued at 1223 AM EDT SAT OCT 18 2025 Observed temperatures in some of the coldest sheltered valleys in our northeastern counties are at or below forecast lows, so adjusted the overnight forecast minimums down to at least match the current temperatures. Overall, made minor adjustments to Sky grids in addition to the hourly T/Td updates for the next several hours. Temperatures in these areas could still fall another few degrees before dawn, but with no significant impacts as temperatures are too warm for frost formation. UPDATE Issued at 925 PM EDT FRI OCT 17 2025 With occasional breaks in the cloud cover anticipated based on current and anticipated satellite trends, lowered Sky grids about 20 percent through the remainder of the overnight. Otherwise, the forecast is on track with no significant changes. && .SHORT TERM...(This evening through Saturday night) Issued at 431 PM EDT FRI OCT 17 2025 Another tranquil October afternoon is unfolding across eastern Kentucky, with temperatures mainly in the 70s and low dew points, courtesy of a 1018 mb surface high centered over Lake Ontario at 20Z. Aloft, a 500 hPa ridge axis extends from the Florida Panhandle northward across Kentucky and Michigan to James Bay. Upstream, a negatively-tilted trough extends from Manitoba to the Lower Colorado River Basin. This is mirrored at the surface by an 989 mb low near or over Lake Winnipeg, while an associated cold front arcs southeastward across Minnesota and then southwestward into New Mexico. A trailing northern stream upper-level trough extends from the Northwest Territories to the Northern U.S. Rockies. The upper-level ridge and its associated surface high will gradually propagate eastward tonight and Saturday, moving off the Atlantic Seaboard during the second half of the weekend. Meanwhile, the aforementioned trailing trough will dig deeply as it dives southeast this weekend, effectively capturing the leading upper-level trough and becoming a deep, negatively-tilting trough over the Great Lakes and Ohio Valley by Sunday. The aforementioned cold front, preceding the trough axis, will become the focal point for rapid cyclogenesis, initially over the Osage Plains on Saturday evening before racing northeast and deepening to an 985 mb low north of the Great Lakes by Sunday afternoon. Modest southerly return flow tonight and Saturday will give way to an intensifying warm conveyor belt jet pumping warmth and moisture into eastern Kentucky on Saturday night with some GEFS mean 850 mb winds of 40 to 50 kts, or 95th-plus percentile relative to climatology. In many cool season events, low-level stability with a warm frontal inversion, often enhanced by rainfall, would be sufficient to preclude substantial momentum transfer from the warm conveyor belt jet to the surface. However, as this event approaches, the low-levels are likely to be dry and more mixed as the surface pressure gradient will become sufficient (more than 4 mb across the area) for valleys that decouple early Saturday evening to recouple overnight. Additionally, virga falling into the dry sub- cloud layer ahead of the front could lead to sufficient low-level lapse rate steepening for at least moderate momentum transfer to the surface until the low-levels become saturated and prohibitive to substantial momentum transfer until the arrival of the front. The front appears to be sharply defined with this system, likely forcing a narrow line of convection (QLCS). While instability will be minimal and model sounding equilibrium levels are low (generally warmer than -20C), strong forcing and rapidly steepening lapse rates up to 850 mb or deeper along the boundary could support strong momentum transfer right along the frontal boundary, especially so in any segments of the line that become more N-S to NW-SE oriented. This scenario could lead to instances of damaging winds (noted in the SPC Day 2 and 3 Marginal CWO), despite insufficient instability for thunder in most cases. Guidance generally favors stronger winds surfacing ahead of the front around 8Z Sunday, with the actual frontal passage occurring between 11Z and 17Z, west to east. While winds may slacken for a few hours immediately behind the front, the combination of diurnal surface heating, strong CAA, and a still- robust 30 to 40 knot westerly 850 mb jet will set the stage for a blustery afternoon with falling temperatures. GFS/NAM mixed-layer momentum transfer guidance from BUFKIT continues to support widespread gusts of 30 to 40 mph through much of the afternoon, with the strongest gusts near and north of I-64. Shallow convective showers in the post-frontal environment on Sunday afternoon could lead to locally stronger wind gusts. The tumble in 850 mb temperatures, from 12-15C at sunrise to 2-5C by sunset, will lead to falling surface temperatures through Sunday afternoon. In terms of sensible weather, fair conditions are expected for this evening and tonight. Temperatures will fall into the low to mid-50s for most, though some of the normally colder hollows could dip into the 40s. On Saturday, mostly sunny skies will prevail, with temperatures warming well above normal into the low to mid-80s, aided by a southerly breeze. After a lull Saturday evening, south to southwest winds will become increasingly gusty overnight, likely reaching a peak with a narrow line of showers and possibly a thunderstorm on Sunday morning. Overnight temperatures will hold nearly steady in the 60s or even rise slightly. Strong winds, gusting between 30 and 40 mph, and gusty showers are expected on Sunday afternoon. Temperatures will start the day in the 60s to near 70, but will fall into the 50s by sunset. .LONG TERM...(Sunday through Friday) Issued at 304 PM EDT FRI OCT 17 2025 The forecast period begins at the transition point between two synoptic features. First, the weekends strong cold front will depart, leaving lingering impacts over eastern Kentucky. To the west, surface high pressure will begin nudging into the region. Basically, the frontal boundary will slowly exit the area, and through Sunday night, upper-level height rises and ridging will usher surface high pressure into the region by Monday morning. Behind the departing front, persistent upper-level northwesterly flow will allow for CAA to establish itself overhead, resulting in chilly overnight lows in the upper 30s to low 40s from Sunday night into Monday. Surface high pressure firmly entrenches itself on Monday. However, throughout the day the upper-level ridge axis will shift eastward as a new trough begins to approach the area from the west. This eastward shift introduces southwesterly flow, advecting warmer air into the region. High temperatures on Monday will climb into the mid to upper 60s. Overnight lows Monday night into Tuesday are forecast to be 5 to 10 degrees warmer as the WAA truly takes hold aloft. Concurrently on Monday, the next weather system is forecast to track off the lee of the Rockies into the Central Plains. A strong surface low is forecast to develop and as the associated upper-level trough continues to dig southeast, the surface feature is expected to lift northeast into the Upper Midwest/Western Great Lakes. By Tuesday morning, the vertically stacked upper-level feature is projected to be over the Great Lakes. At the surface, its accompanying cold front will be approaching the CWA. With an 80-to-90 knot jet core swinging overhead and the presence of a surface boundary, there is a strong potential for upper-level momentum to mix down to the surface. Forecast soundings, coupled with indications from momentum transfer, a strong Theta-E gradient, and high LREF probabilities (greater than 90 percent for gusts over 25 mph) indicate that strong wind gusts of at least 25 mph are very likely with the frontal passage Tuesday afternoon. The front itself appears to be moisture starved and the locations most likely to see PoP are areas closer to the Ohio River and north; meaning the forecast area is expected to be dry but windy along the mostly dry cold front. As the area is forecast to remain mostly dry Tuesday night, post-frontal CAA and clear skies will allow for instances of frost development overnight Tuesday. Surface high pressure will build back into the region behind the exiting cold front on Wednesday. Upper-level flow will remain out of the northwest, maintaining CAA behind the front. This CAA is reflected in daytime highs for Wednesday, which are expected to struggle to climb much higher than the lower 60s. For Wednesday night, the combination of clear skies and continued CAA creates the potential for frost development across the sheltered valleys of eastern Kentucky. While overnight lows are generally forecast to be in the 30s to lower 40s, frost will be possible in favorable locations due to anticipated radiational cooling under clear skies. Thursday is forecast to see a subtle warm-up as a surface warm front lifts northeast through the area early Thursday morning. Highs will climb into the mid to upper 60s. However, an upper-level perturbation is forecast to move through the mean flow, leading to increased chances of precipitation beginning Thursday afternoon and continuing through Friday afternoon. At this time, there is noticeable disagreement among long-term deterministic models regarding the precise timing and placement of the Thursday/Friday synoptic features. Nonetheless, the overall trend indicates a potential for scattered rain chances from Thursday through Friday. Overall, the forecast period will be highlighted by multiple passing disturbances bringing gusty to strong winds, some rain, and notable temperature fluctuations. Temperatures will begin to trend toward values expected for mid to late October, with the added potential for isolated frost on Tuesday night and again Wednesday night. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 213 AM EDT SAT OCT 18 2025 Passing disturbances should continue to bring high and some mid level clouds during the first 6 hours of the period. Valley fog with reductions to MVFR and IFR is also anticipated through around 13Z or 14Z and K1A6, KBYL, and KI35 may be affect, through the TAF sites will not be affected. Outside of that, VFR conditions will prevail. However, following light and variable winds through around 13Z, but the approach of a strong cold front will bring increasing south to southwest winds Saturday peaking between 5 and 12 KT through 22Z before winds become more southerly and 10KT or less sustained. Increasing winds just off the surface will bring a threat for low level wind shear to end the period. && .JKL WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...JP SHORT TERM...GEERTSON LONG TERM...VORST AVIATION...JP