Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 221118 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 718 AM EDT Sun Oct 22 2017 .UPDATE...
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Issued at 718 AM EDT SUN OCT 22 2017 Seeing typical morning valley fog that will lift and dissipate by mid morning. Higher clouds have thinned considerably but another upstream band has yet to push through. Update required some minor tweaks to the hourly grids for current trends and obs. No update to the zone package at this time.
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&& .SHORT TERM...(Today through Monday) Issued at 450 AM EDT SUN OCT 22 2017 Ridging aloft and at the surface will yield to a storm system coming together over the Midwest and Ohio Valley region during the next 36 to 48 hours. Previous model runs advertised digging, amplifying northern stream energy lifting a southern stream disturbance up out of the deep south and through the Ohio Valley region with little if any phasing. Most recent runs however show more phasing, resulting in a slightly slower overall evolution of the storm system through our area. This has slowed the onset of precipitation into our area just a bit, now more solidly into the Monday morning time frame. At the surface, low pressure will ride north out of the Gulf of Mexico and into the Ohio Valley by Monday. Ample gulf moisture will be pulled up into the area as this wave of low pressure phases with an incoming cold frontal boundary which will be moving into the mid Mississippi Valley later today. This will result in a good soaking rain for our forecast area, with between one and two inches possible across most of the area for the event. Until then we have one last day of fair and pleasantly warm weather as temperatures climb close to the 80 degree mark later today. Trends suggest a little subsidence ahead of the approaching system to our west, which may help scour our the thicker high level cloud cover as the day progresses. While this may allow for a little better heating it will be offset with lowering heights. Thus afternoon highs may end up being very similar to yesterday`s, possibly a degree or two warmer overall. Rainfall will overspread the area from the southwest late tonight, reaching our far southwestern zones during the predawn time frame, and the heart of our CWA closer to dawn. For Monday, rain cooled highs will only manage to climb into the mid and upper 60s. .LONG TERM...(Monday night through Saturday) Issued at 413 AM EDT SUN OCT 22 2017 The extended forecast begins on Monday night with a deepening longwave trough digging southeast into the OH Valley. This, exhibiting a rather amplified upper level pattern beginning the extended. A closed 500MB low develops and lifts northeast out of the area as precip associated with the low exits eastern Kentucky by Tuesday morning. Given the lack of instability apparent in the GFS model sounding, rainfall Monday night and through the day on Tuesday will be more showery precip with no thunder expected.`As some of the coldest air of the season so far advects into the region, a secondary wave behind the front will push in from the northwest with another chance of showers expected in northeast and eastern Kentucky Tuesday night and into the day on Wednesday. With coldest part of the fall like airmass reaching the area on Wednesday, the 0 degree 850MB isotherm will dip into eastern Kentucky. In fact. highs on Wednesday will barely make it out of the 40s for highs in some parts. With lows Thursday morning dipping into the mid 30s and dew points dropping into the low 30s, widespread frost will be an impact to vegetation. The upper level pattern begins to shift to a more progressive flow as brief ridging will keep eastern Kentucky dry for Thursday and much of Friday. The pattern then begins to amplify again as a second trough digs south as another front pushes southeast through the OH Valley. At this point, the front seems to be lacking the instability so will keep thunder out of the forecast at this point as well. However, another good soaking rain looks to be on tap for next weekend with another shot of cold air, possibly colder than the last. && .AVIATION...
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(For the 12Z TAFS through 12Z Monday morning) ISSUED AT 718 AM EDT SUN OCT 22 2017 VFR conditions are expected through the forecast. However, CIGS and VSBYS will begin to drop just beyond the end of the forecast window, by around dawn as rain showers begin to overspread the area. Still picking up our typical valley fog on the regional satellite but nothing is affecting any of our terminals. High clouds have thinned out considerably but another upstream band has yet to push through. Light southeast winds along the ridgetops will veer through the morning, becoming southerly and increasing to around 10 kts.
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&& .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...RAY SHORT TERM...RAY LONG TERM...SHALLENBERGER AVIATION...RAY

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