Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 211900 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 300 PM EDT Sat Oct 21 2017 .SHORT TERM...(This evening through Sunday night) Issued at 300 PM EDT SAT OCT 21 2017 A ridge of high pressure will bring dry and warmer than normal weather to eastern Kentucky through early Sunday evening. Scattered to broken high level cloud cover will stream across the area during that time. Highs on Sunday should be similar to today, with max readings in the upper 70s to lower 80s expected. Tonights low will also be warmer than normal, with minimum readings ranging from the upper 40s to the mid 50s across the area. Cloud cover will finally begin to increase Sunday evening, as a large trough of low pressure aloft, and its attendant surface cold front, begin moving across the region. We should see the first rain showers begin moving into the southwestern portion of the forecast area late Sunday night. .LONG TERM...(Sunday night through Friday) Issued at 430 AM EDT SAT OCT 21 2017 Models are in good agreement through the bulk of the extended portion of the forecast, with more significant differences showing up in the latter 48 hours or so. The Canadian solution appears to be the outlier, with slightly better agreement between the ECMWF and GFS. While not great, the ECMWF has shown the best consistency through the last couple of runs. Overall the pattern is amplified and progressive. Digging, amplifying northern stream energy appears to lift a southern stream storm system up and through the Ohio Valley region early in the period. But significant differences in details remain with strength and timing of short wave energy tracking through the core flow of the eastern CONUS trough. Bottom line is that some phasing of these two systems will be possible which would influence the evolution and timing of events through the first half of the extended. Mid and upper level pattern then shifts rapidly during the last 72 hours of the period as the eastern CONUS trough lifts out to the northeast in response to energy carving out a deep trough across the western CONUS. The ECMWF is a bit more amplified and slower with the evolution of the pattern in general and digs the trough further west. The GFS advertises a much broader trough that encompasses just about the entire lower 48, which in turn brings storm systems further east more rapidly with time. For sensible weather a low pressure system will develop over the Gulf of Mexico and move rapidly northward, through the deep south and into the Commonwealth by Monday. This system will bring ample moisture and produce a soaking rain for our area. At present much of the area could see between an inch and an inch and a half of rainfall from Monday through Tuesday. A strong cold frontal system will sweep southward into the region late Monday night and through eastern Kentucky by early Tuesday morning. Immediately after a clipper like system will drop rapidly southeastward out of Canada and through the upper Ohio Valley by late Wednesday. Combined these three systems will usher in a breif shot of much colder air for our area during the mid week time frame. Temperatures will be low enough Thursday morning that frost will be a possibility, especially in our more sheltered valley locations. Thereafter temperatures moderate back up to normal levels through the remainder of the forecast window. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 122 PM EDT SAT OCT 21 2017 The TAF sites should experience VFR conditions through out the period, with light winds and dry conditions also expected. The only cloud cover of note should be SCT to BKN high clouds that will persist during the period as well. Any fog that forms late tonight should be confined to valley floors and near bodies of water. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...AR LONG TERM...RAY AVIATION...AR is the U.S. government's official web portal to all federal, state and local government web resources and services.