Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 152041 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 341 PM EST Wed Nov 15 2017 .SHORT TERM...
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(This evening through Thursday night) Issued at 340 PM EST WED NOV 15 2017 A cold front is poised to shift southeast across the Ohio River and across portions of Kentucky late this afternoon, traversing eastern KY this evening and overnight. WPC shows this front exiting just SE of the state after 9Z. A line of precip is moving in ahead of this frontal boundary, in the form of rain. This precip line is currently making its way into the NW CWA and will continue to shift eastward across the CWA through the evening and first part of the overnight. Just behind the frontal passage, dry air will move in and cut off precip potential. This dry air will cut off the mid level moisture first, leaving llvl moisture trapped below a pretty steep inversion. As such, did include some patchy drizzle in on the backside of the precip as it is tapering off after 6Z. For Thursday, deamplified ridging moving across the south central conus, and a shortwave exiting NE of the Ohio Valley will result in rising heights across our region. An area of surface high pressure across the mid and upper Mississippi Valley at 1Z Thursday will shift eastward across the Ohio Valley and Kentucky Thursday and Thursday night. This dry westerly flow and rising heights will promote mostly clear skies but post frontal temperatures that are some 10 degrees below seasonal normal, in the upper 40s and low 50s. By thursday night, the location of the high will be passing almost directly overhead, subduing winds and making for ideal conditions for net radiational cooling. Ridge valley splits will be likely, especially in the east. Dropped the far east valleys down around 5 degrees from rest of the CWA, but wouldn`t be surprised if this spread ends up being even more. Rain tonight could provide enough lingering moisture to also promote fog, especially in theses cooler valleys. Did include patchy to areas of fog in the deeper valleys as well. .LONG TERM...(Thursday night through Tuesday) Issued at 406 AM EST WED NOV 15 2017 Surface high pressure passing through the Ohio Valley at the start of the period will bring mainly clear skies. Once the high passes to our east, winds will turn back toward the south and temperatures will moderate on Friday. The only precip to contend with during the long term period will come from a cold front passing through during the weekend. Warm air advection will be joined by moisture advection as the front approaches. Models are still not in sync for timing, but are at least showing less variability (both between models and run to run) than in recent days. A compromise solution places cold fropa late Saturday. While some rain can`t be ruled out in the warm air advection pattern ahead of the front in our northern counties on Friday night, most of the rain should come with the front, with the highest POP shifting southeast across the region Saturday afternoon and evening. The parent low sending the front through our area will become very deep as it crosses the Midwest and Great Lakes, and its wind flow will be effective at sending a very chilly and dry air mass southward for Sunday. It will result in dry weather to start the week, with temperatures well below normal. Daily sunshine will help readings to moderate with time, also aided by a return of south to southwest winds by Tuesday.
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&& .AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon) ISSUED AT 108 PM EST WED NOV 15 2017 A cold front is continuing to push towards the Ohio River early this afternoon with breezy SW winds, and should be reaching eastern Ky later this evening, traversing through overnight. Rain will move in ahead of this frontal boundary, starting during the afternoon and then tapering off just behind the frontal boundary overnight. Tried to time out rain impacts at each TAF site. Expect visibilities to generally remain VFR as rain moves through, though some of the heavier showers could briefly reduce to lower vis. CIGs will slowly be deteriorating throughout the evening/overnight, with IFR conditions (near or at Alternative Minimums) possible generally after 3Z. Drier air moving in near the morning will allow skies to quickly improve and clear out, with VFR mostly clear conditions and light westerly winds expected for the remainder of the TAF period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...DJ LONG TERM...HAL AVIATION...JMW

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