Area Forecast Discussion
Issued by NWS Jackson, KY

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456 FXUS63 KJKL 191500 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1000 AM EST Sun Feb 19 2017 .UPDATE...
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Issued at 1000 AM EST SUN FEB 19 2017 14z sfc analysis shows weak high pressure moving over Kentucky. This has not been able to make much progress in eroding the low clouds across the area this morning. While the fog has dissipated, the low clouds look to hang around for much of the day per the latest HRRR and time heights from the NAM12 so have dropped high temperatures by about a category for this update along with beefing up the clouds. A few sprinkles will be possible early on - mainly in the east - but should all dry up by noon. Current temperatures are running in the upper 40s and lower 50s while dewpoints are not much lower - in the mid and upper 40s with light and variable winds. The grids have been updated to reflect the above and also the latest obs/trends. These have been sent to the NDFD and web servers. UPDATE Issued at 651 AM EST SUN FEB 19 2017 Patchy drizzle making headway toward the Virginia state line, in accordance with eastward progression of a weakening upper low. Low stratus will hold in place much of the morning as patchy fog mixes out. Warmer air moving in aloft and gradual clearing this afternoon should still allow for temperatures to top out in the low-mid 60s.
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&& .SHORT TERM...(Today through Monday) Issued at 347 AM EST SUN FEB 19 2017 Areas of drizzle will continue to move across eastern Kentucky early this morning as the deformation zone of a filling upper low pushes across the Appalachians into the Atlantic. Portions of the Big Sandy region into northeastern Kentucky could squeak out a hundredth of an inch nearer the greater upper lift, but not expecting much more than some morning dampness underneath abundant stratus cloud cover. Patchy fog should also hang around until early-mid morning as mixing ensues, thus allowing surface visibilities to improve. Deep layer subsidence will move overhead later this morning through this afternoon, bringing gradually clearing skies and an end to any lingering drizzle. Warmer temperatures will advect in aloft with 850 mb temperatures rebounding into the 7-9C range, but a strong and lowering subsidence inversion may hinder boundary layer mixing into this. Nonetheless, above average temperatures will once again be in place with highs climbing into the low-mid 60s. High pressure, leading to light winds and clearing skies this evening/tonight, and the lack of any appreciable dry air advection will lead to fog development later this evening through tonight. Crossover temperatures in the mid 40s will easily be reached tonight as ridgetop low temperatures fall into the low-mid 40s with valleys cooling into the mid-upper 30s. Have thus made mention of patchy fog across much of eastern Kentucky with areas of dense fog in the valleys. High clouds will be on the approach downstream of a trough moving into the Great Plains, but this does not look to have a large impact on near-surface cooling. Further warming is in store for Monday as a low-level thermal ridge slides overhead, promoting high temperatures in the upper 60s to low 70s. .LONG TERM...(Monday night through Saturday) Issued at 347 AM EST SUN FEB 19 2017 The extended period will feature well above normal temperatures and alternating periods of dry and wet weather. The period will start off dry, as a ridge of high pressure slowly moves off to our east. The dry weather will likely come to an end on Tuesday, as a slow moving frontal boundary moves toward the area. The front should move across the area very slowly Tuesday and Tuesday night. The problem with this initial boundary will be a lack of good upper level support and a poor temperature contrast across it. This will make for a relatively weak and diffuse front that will have little lift and instability associated with it. This will mean scattered light rain showers will most likely move through eastern Kentucky Tuesday and Tuesday night, as the front passes through. The rain should be out of the area by Wednesday afternoon. The next round of rain currently being forecast is for the period Wednesday night through Saturday, as a series of weather systems are progged to move across this part of the country. The models are currently showing differences in timing of the passage of the weather systems, and the areal extent and amounts of precipitation associated with them. That being said, it does appear that a couple of frontal boundaries may move across the Ohio and Tennessee valley regions from mid week onward, bringing multiple rounds of precipitation to eastern Kentucky. The question will be exactly when this happens and how much rain we end up with. Decided to make slight modifications to the blended model data from Wednesday night onward, going with lower precipitation chances overall than the model blend gave. Also did not see enough evidence in the model data to warrant including thunder in the forecast at this time. Temperatures the first several days of the extended will feel much more like late spring than late winter, with highs in the upper 60s and lower 70s expected Tuesday through Friday across the area. A cool down is then expected for the upcoming weekend, as a cold front moves through and eventually allows cooler air to invade the area. Even though it will be much cooler next Saturday than during the rest of the week, Saturdays highs are still forecast to be in the 50s, which is still well above normal for this time of year. Nightly lows are forecast to be in the 40s and 50s. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) ISSUED AT 651 AM EST SUN FEB 19 2017 IFR/MVFR ceilings will remain in place this morning as high pressure builds east toward eastern Kentucky. Patchy fog will lead to scattered IFR/MVFR visibilities this morning, before mixing out later this morning through this afternoon. VFR conditions should return by mid afternoon as winds remain light out of the west/southwest near or below 5 knots through the period. Fog development late this evening and tonight currently looks widespread enough to impact all area terminals at some point prior to 12Z Monday. More sheltered valleys will likely see areas of dense fog while higher ridgetops may only see slight visibility reductions. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GUSEMAN LONG TERM...AR AVIATION...GUSEMAN is the U.S. government's official web portal to all federal, state and local government web resources and services.