Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 062120 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 420 PM EST Wed Dec 6 2017 .SHORT TERM...
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(This evening through Thursday night) Issued at 420 PM EST WED DEC 6 2017 Highly amplified pattern continues aloft across the CONUS with a very deep trough stretching from the Hudson Bay all the way to central Mexico. A minor impulse of short wave energy will track through the trough Thursday with little effect on our area except some extra cloud cover and a reinforcing shot of cold air. More substantial energy will round the trough and enter the lower Ohio Valley Region by late Thursday night. Sensible weather will see a surface trough or boundary swing through eastern Kentucky during the day Thursday. For now kept our weather dry though a couple of the higher resolution models hint at the potential of some flurry activity along and north of Interstate 64. With a respectable mean westerly gradient wind the boundary layer remains fairly mixed through the period so do not see much in the way of ridge valley split potential tonight or Thursday night. In addition, CAA patterns typically keep our ridges (thermal belt) cooler than our valleys anyway. .LONG TERM...(Friday through Wednesday) Issued at 420 PM EST WED DEC 6 2017 A large, deep trough will dominate much of the central and eastern CONUS during the long term period. Two systems are forecasted to progress through our CWA. The first will pass through on Saturday. The models have come into better agreement with the timing and intensity of this particular system. However, the models differ with the second system forecasted to come into the area on Tuesday. The ECMWF shows a bit more intense, two wave system Tuesday into Wednesday night. The GFS, however, shows an initial system moving in on Tuesday and breaking up through Wednesday night. Due to the uncertainty of the models, the confidence is low on the second system, particularly on the intensity and set up. However, timing could be a concern as well this far out in the forecast. The main theme with temperatures during the long term is cold. This will continue through Sunday with a slight warm up on Monday with WAA and S/SW wind flow into the region. With the second system moving in on Tuesday, temps will cool down again Tuesday and Wednesday. The coldest temps will occur Saturday night and Tuesday night with the passage of the two systems bringing in colder Arctic air from the north. In terms of precipitation, the intensity of the first system on Saturday has decreased with latest model runs. The precip that will fall will be light and mainly snow since wet bulb temperatures remain below freezing and with 850mb temps around negative 7 degrees, which will get colder with the passage of the system. All of these factors should limit overall snow accumulations.
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&& .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) ISSUED AT 1243 PM EST WED DEC 6 2017 VFR conditions through the period with a predominant westerly wind between 5 and 10 kts through the period. Exception will be overnight as winds slacken a bit. Thicker high cloud deck about 18 kft will move off to the northeast by this evening. Additional lower cloud cover around 5 kft will overspread the area Thursday as a disturbance pushes through the region. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...RAY LONG TERM...CGAL AVIATION...RAY

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