Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 180850 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 450 AM EDT Mon Mar 18 2024 .KEY MESSAGES...
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- A deep trough passing aloft brings a threat of light snow showers and flurries this afternoon. - A hard freeze later tonight could kill any cold sensitive vegetation that has emerged prematurely due to early season warmth. - Gusty southwest winds transport warmer air into the region on Tuesday, but dewpoints are slower to rise leading to low afternoon relative humidity and Fire Weather concerns. - Temperatures rebound back to near normal for Wed and into next weekend, with lower confidence in the next potential chance of precipitation moving in towards the end of the work week.
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&& .SHORT TERM...
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(Today through Tuesday) Issued at 450 AM EDT MON MAR 18 2024 08Z sfc analysis shows high pressure attempting to build into eastern Kentucky from the west. However, a passing trough aloft will help to maintain cyclonic sfc flow over the area into the evening. This flow is responsible for the chilly temperatures this morning on northwest winds of 10 mph or less. Accordingly, readings are running in the low to mid 30s most places with a few sheltered spots able to cool into the upper 20s. Meanwhile, dewpoints are lower than temperatures, generally in the upper teens to lower 20s under a smattering of mainly high clouds. The models, and their individual ensemble suites, continue to be in pretty good agreement aloft through the short term portion of the forecast. They all depict a deep trough tilting through the southern Ohio Valley and across the Tennessee Valley today. This brings strong height falls, steep lapse rates, and a cluster of mid level energy through our moisture starved area this afternoon. This trough bottoms out to our south this evening and slips quickly east of the Appalachians leaving lower heights and northwest flow at 5h behind. The now very small model spread supports using the NBM as the starting point for the forecast grids with most adjustments related to terrain distinctions in temperatures tonight as well as extra mix down drying on Tuesday afternoon. Sensible weather will feature a cold day after our warmth of late with a northwest breeze adding to the chill. Dry conditions in the boundary layer should keep any light pcpn in the form of flurries and sprinkles, though an influx of moisture from the Great Lakes may be enough for a stray shower of light rain or snow (10 percent threat or less) - but more probable northeast of the JKL CWA. The clouds and light pcpn associated with the passing trough aloft will move off to the east tonight. These conditions, when combined with diminishing winds, will allow for better for better radiational cooling and a ridge to valley temperature difference to set up overnight and into Tuesday morning - enhancing the widespread hard freeze in the valleys especially. The recent warmth has encouraged many buds and blossoms to develop on the vegetation throughout the area and these are seriously threatened by tonight`s cold. For this reason (as the growing season has not been declared started, yet) an SPS has been issued giving heads up to those with agricultural and fruit tree interests. For Wednesday, the dry conditions combined with rebounding temperatures on breezy southwest winds will lead to humidity values well below 25 percent, for most. Combined with the winds pushing 15 mph sustained, at times, from mid morning into the afternoon there will be heightened fire weather concerns and a Red Flag Warning may be needed for at least portions of the forecast area for the latter part of the day. This concern will be addressed in the narrative portion of the forthcoming Fire Weather Forecast product. The main adjustments to the NBM starting point were to include more terrain distinction for temperatures tonight and also favor the 10 percent or lower version of the NBM for dewpoints on Tuesday afternoon. .LONG TERM...(Tuesday through Sunday) Issued at 332 PM EDT SUN MAR 17 2024 The primary forecast concerns in the extended will be the potential for low dewpoints and very dry conditions across the area on Tuesday and generally above normal temperatures. With winds still expected to be blustery and perhaps a bit gusty to begin the period, there could be some fire weather concerns for eastern Kentucky. This threat has been highlighted in the HWO. A ridge of high pressure will be the dominant weather system to start, but a weak area of low pressure passing by to our south, will bring rain chances back into the picture late in the week and into the upcoming weekend. The overall large scale upper level pattern to begin the period will feature a trough of low pressure moving slowly into and across the Desert Southwest and across the southern CONUS over time. This will be the system that brings rain to our area toward the end of the period. High pressure will dominate the weather of the southeastern CONUS initially, but another expansive trough of low pressure is forecast to dive southward out of Canada Wednesday and Wednesday night. Since it appears this system will be moisture starved, we should see nothing more than scattered clouds across the area as this system moves through aloft to our north and northeast. The southern stream trough mentioned earlier, will be our next weather maker Thursday night through Sunday. Another weak northern stream system might also be moving through during this time, and could influence our weather as well, but the southern stream low still looks like the main show.
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&& .AVIATION...(For the 06Z TAFS through 06Z Monday night) ISSUED AT 155 AM EDT MON MAR 18 2024 VFR conditions will prevail through the period with just a smattering of high clouds into daybreak. A passing deep upper level disturbance will move through the region during the day. This brings scattered to broken clouds ranging from 4-6k feet agl, with perhaps a fleeting sprinkle or flurry. Winds will continue to be the main aviation concern at the terminals, though. They will be light into dawn then pick up from the northwest increasing to around 10 kts, with gusts of 15 to 20 kts by mid to late morning, as deeper mixing commences across the area. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...AR AVIATION...GEOGERIAN/GREIF

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