Area Forecast Discussion
Issued by NWS Jackson, KY

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506 FXUS63 KJKL 230251 AAB AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1051 PM EDT Sat Oct 22 2016 .UPDATE...
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Issued at 1050 PM EDT SAT OCT 22 2016 Hourly temperatures have been freshened up based on trends in observations. High pressure will bring mostly clear skies and light winds overnight. Lows in the valleys should reach the mid to upper 30s range with patchy frost especially in the normally colder locations. Frost wording has been adjusted in the HWO for patchy frost in more of the valleys. UPDATE Issued at 755 PM EDT SAT OCT 22 2016 Temperatures in some of the deeper eastern valley locations have already dropped into the low to mid 40s with winds having slackened or decoupled there. This combined with afternoon crossover temperatures in the mid 30s have opted to lower min T for some of the typically colder valley locations a couple of degrees on average. Patchy frost will be possible in some of these locations.
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&& .SHORT TERM...(This evening through Sunday night) Issued at 345 PM EDT SAT OCT 22 2016 19Z sfc analysis shows high pressure building into the area as low pressure pulls away to the east. This is working to clear the sky from west to east as the drier air advects in on northwest winds. In general, the winds are running at 5 to 10 mph with a few gusts to 15 mph, or so, thanks to good mixing. The return of sunshine helped temperatures this afternoon climb into the mid 50s for most locations while dewpoints mixed down to the low and mid 30s. These lower dewpoints should make it tougher to get fog late tonight but may hint at a potential for valley frost. The models are in good agreement aloft through the short term portion of the forecast as they all depict a large trough gradually pivoting out of the Ohio Valley. The core of the initial trough will depart tonight with heights rising locally, but additional energy does dive into the Great Lakes, though on a more shallow trajectory, Sunday night. Given the good model agreement will favor a blended solution with a lean toward the higher resolution HRRR and NAM12. Sensible weather will feature a chilly night with mostly clear skies and good radiational cooling. This should be enough for some upper 30s in the valleys and a spot or two of mid 30s where patchy frost is possible. Do not anticipate the frost being extensive enough for an advisory tonight as it will be confined to just the deepest, most sheltered valleys. Accordingly, will highlight it in the HWO with a the potential for an SPS left to the following shift. Saturday will be a very nice mid autumn day with plenty of sunshine, breezy conditions, and temps in the mid 60s. A few wind gusts will approach 30 mph Sunday afternoon over western parts of our area. Another cool night follows with mostly clear skies and another ridge to valley temperature split, but likely not quite cold enough for any frost. Used the CONSShort and ShortBlend as a starting point for the grids with some adjustments each night for lows - enhancing the ridge to valley differences. PoPs are essentially zero - in line with all guidance. .LONG TERM...(Monday through Saturday) Issued at 440 PM EDT SAT OCT 22 2016 The models are in fairly good agreement aloft through the bulk of the extended. A flat ridge will spread through the South during the first part of the week before another wave starts developing over the Northern Plains moving east. It is this wave that leads to a greater spread in the models as it moves into the Upper Midwest with the GFS outpacing the ECMWF and both stronger than the Canadian. The wave deepens into a strong trough Wednesday into Thursday - deepening substantially as it moves into and through the Great Lakes to end the work week. Its energy brushes by the Ohio Valley with its trough axis passing through Kentucky early Friday. Heights will then rise for next weekend, more so from the GFS, and quicker, than the ECMWF. Given the broad agreement through the majority of the period a blend looks to be a reasonable starting point for the grids. Sensible weather will feature a fairly nice stretch of weather through mid to late week with dry conditions and moderating temperatures. A dry front will shift east of the area Monday with little change in air mass. The next cold front will move toward and through the area on Thursday with a decent shot at showers into Friday morning. Cannot rule out a stray thunderstorm with this, but given the time of year will wait until it gets closer to further evaluate the thunder threat. Dry weather follows into the weekend, but there may be another front worthy of some PoPs by Saturday afternoon per the GFS and that night in the ECMWF. For now, will keep it dry Saturday while the models work this difference out. The main adjustments to the CR init was to hit the terrain effects more each night and tighten up the PoPs late in the upcoming work week. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 759 PM EDT SAT OCT 22 2016 VFR conditions will prevail throughout the period as high pressure dominates. Some river valley fog cannot be ruled out but should be confined to the deepest river valleys towards dawn and not impact the TAF sites. Winds will slacken overnight, but pick up around 15Z with some gusts approaching 20 kts possible under clear/sunny skies. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GREIF LONG TERM...GREIF AVIATION...JP is the U.S. government's official web portal to all federal, state and local government web resources and services.