Area Forecast Discussion
Issued by NWS Jackson, KY

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569 FXUS63 KJKL 171542 AAB AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1042 AM EST Tue Jan 17 2017 .UPDATE... Issued at 1040 AM EST TUE JAN 17 2017 Radar trends and many of the short term model runs were in good agreement bringing an area of showers across the Lake Cumberland Region and across the Cumberland Valley and Ky Cumberland Mountains area. Pops in this area were raised to categorical for a couple of hours with those transiting out by early afternoon. However, with the cold front an a shortwave trough still upstream, chance to low end likely pops were held onto for a few hours into the afternoon as some redevelopment seems probable. Temperatures behind this band are in the low to mid 60s and even warm air advection ahead of the front without much in the way of sunshine the CWA should experience similar temperatures during the early to mid afternoon and this will be enough to break the record high for the 17th at JKL. The current record is 62 from 1990. UPDATE Issued at 640 AM EST TUE JAN 17 2017 Did a quick update to the grids early this morning primarily to fine tune the PoPs and Wx through the next few hours based on the latest RADAR trends and HRRR guidance. Also tweaked the T and Td grids per the current obs and trends. These have been sent to the NDFD and web servers. && .SHORT TERM...(Today through Wednesday) Issued at 345 AM EST TUE JAN 17 2017 08z sfc analysis shows a well defined area of low pressure lifting northeast into the Great Lakes. This is dragging a cold front slowly east through the Mid Mississippi Valley and toward Kentucky. Additionally a northward moving warm front is currently lying across eastern Kentucky with a large area of convection rolling east along it. This cluster of showers, with a potential for embedded thunderstorms will continue to press deeper into eastern Kentucky from the west with a healthy dose of soaking rains expected for most places by dawn. The clouds and arriving showers, along with south stirring winds, have mostly mixed out the colder valleys, but there remain a few in the east that did manage to get into the upper 40s while most of the rest of the area reside in the mid to upper 50s with lower 60s found in several places south of Jackson. Dewpoints, meanwhile are running in the low to mid 50s most places. This is making for another quite mild mid January night - sitting at or near record max minimum temperatures - across the area. The models are in only fair agreement aloft through the short term as the southeast ridge holds fast no matter what troughs move by to the northwest. This will mean deep level southwest flow will continue supporting our current spate of mild and wet conditions through the near term. Specifically, an opening, southern stream, wave will shift off to the north of Kentucky today. This is followed by a fairly strong northern stream trough digging through the Ohio Valley tonight - only briefly dampening the heights over the region. The model spread is rather large for this feature particularly given that it is only 24 to 36 hours out. The ECMWF is a tad sharper and slower with this when compared to the GFS - but not as slow as the NAM. This wave will be driven in part by a 300 mb jet streak passing to our north with sustained upper level divergence over Kentucky today and tonight on its right entrance region. Ridging rapidly builds back over Kentucky later Wednesday in all models in the wake of the northern stream wave. Given the lowered confidence with that second wave tonight have favored a blended solution along with a lean toward the higher resolution HRRR for the near term. Sensible weather will feature a wet start to the day as a leading band of showers moves through eastern Kentucky followed by a brief lull around midday. By late afternoon another round of showers and potential thunderstorms will seep northeast into the area just ahead of a weakening cold front that pushes through during the first part of the night. Cooler and drier conditions follow into Wednesday morning, but readings will still be well above normal, as well as freezing, through the short term with a small rebound by the afternoon as high pressure quickly moves into the Ohio Valley. Started with the CONSShort and ShortBlend for most elements through the short term portion of the forecast - making only minor adjustments to temps and winds today. Also, adjusted PoPs more toward the HRRR in the near term. .LONG TERM...(Wednesday night through Monday) Issued at 305 AM EST TUE JAN 17 2017 Pretty good agreement between the model for the extended period. The general consensus is that a series of upper level southern stream weather systems will move across the Ohio and Tennessee valley regions. The first systems is forecast to move out of the souther Plains Wednesday night and Thursday. This system should bring rain to our area Thursday and Friday. The models agree that rain showers should being entering our area early Thursday morning. The rain will overspread the area from south to north through out the day on Thursday. The best chance for rain with this initial system should be from late Thursday afternoon through early Friday afternoon, as an area of low pressure by just to the north of the Ohio River and into the central Great Lakes region. After this first round of rain exits the area, we should experience a short break from precipitation, as a weak ridge of high pressure aloft sets up over the southeaster CONUS Friday night through early Saturday night. A second slightly strong area of low pressure is then expected to approach the area from the southern Plains Saturday night. This system may be slower moving than the first, so we could see a longer period of rain this weekend and into the beginning of next week. The first showers with this second system should move into eastern Kentucky late Saturday night. The rain will then gradually spread across the area on Saturday, with the entire area likely seeing accumulating rainfall by Saturday evening. The period from Saturday night into early Sunday morning looks to be quite wet, as the area of low pressure nearly stalls over top of us. This would allow the rain to linger across the area through Monday night. Temperatures through out the entire period will be well above normal for the time of year. Highs during the extended will vary from the 50s to the 60s each day, with nightly lows generally in the 40s. Some locations could fall into the mid to upper 30s Thursday morning. Some locations along and south of the Hal Rogers Parkway on Friday morning may only bottom out at or slightly above 50 degrees. && .AVIATION...(For the 12Z TAFS through 12Z Wednesday morning) ISSUED AT 650 AM EST TUE JAN 17 2017 VFR/top end MVFR conditions for most TAF sites will continue to worsen through the morning and end up near IFR by midday as cigs lower even as the showers start to scatter out. Fog and mist tonight will likely bring additional visibility restrictions to much of the area. Any low level wind shear will clear up by 15z with gusty winds mixing to the sfc better. A stray thunderstorm or two will also be possible across the entire area through the day. South winds of 5 to 10 kts early will become southwest at 10 to 15 kts, with gusts of around 20 kts expected during the day. Look for the winds to diminish and become more west later tonight. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GREIF LONG TERM...AR AVIATION...GREIF is the U.S. government's official web portal to all federal, state and local government web resources and services.