Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 200333 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1133 PM EDT Wed Apr 19 2017 .UPDATE...
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Issued at 1133 PM EDT WED APR 19 2017 The last of the showers and storms look like they are finally winding down. Will hold onto some isolated POPs for another hour or so matching the radar trends, with the rest of the night looking quiet. Clouds are much less prevalent tonight, compared to last several nights, so have played up the fog more, especially with pockets of locally heavy rainfall having occurred earlier. Lows will range from the mid 50s in the cooler spots, to around 60, where light southerly winds keep things a bit more mixed. Updates have been sent. UPDATE Issued at 755 PM EDT WED APR 19 2017 Mainly freshened up the hourly temperatures and dew points over the next few hours, as localized storms have cooled off places, including JKL. POPs were already in good shape, with a gradual diminishment expected through midnight. Only made a few minor adjustments to these based on the current radar trends.
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&& .SHORT TERM...(This evening through Thursday night) Issued at 433 PM EDT WED APR 19 2017 Scattered showers and thunderstorms have fired across the area this afternoon. These storms are not quick builders, the likely result of slight height rises and relatively weak instability to feed off of. Activity is expected to gradually die down through the late afternoon and early evening as sunset approaches. We will probably see some patchy fog develop through the overnight where precipitation has fallen late this afternoon and/or this evening. Added a mention of fog to the zones, particularly in the valleys. Otherwise, focus turns to a cold front that will drop into the region by late Thursday night into Friday. There is still considerable uncertainty with the details of this system. The GFS and NAM manage to take the boundary considerably further south than the ECMWF. This lowers confidence a bit with respect to sensible weather. Ramped up pops Thursday night as the front approaches but stayed close to model blends and guidance. For sensible weather, expect showers and thunderstorms to gradually die off through sunset. Skies will partially clear allowing for some reasonable radiative cooling. Preferred the inherited cooler valley temps over the warmer blends and model guidance for tonight. This will favor some patchy valley fog, which might tend to become more dense at times where late afternoon and evening precip occurs. Clouds will be on the increase late Thursday afternoon and gradually brought pops back into the picture late in the day. Showers and thunderstorms increase in coverage Thursday night with the cold front dropping into the area. Temperatures will climb to around 80 for much of the area Thursday. .LONG TERM...(Friday through Wednesday) Issued at 433 PM EDT WED APR 19 2017 Overall, there is good model agreement during the period. At the onset, a cold front will have entered KY from the northwest, and will be draped across the southeastern CWA as of Friday morning. It is expected to bring at least scattered showers and thunderstorms, especially east of the front, along the southeastern CWA where moist and warm southerly flow will still be occurring. The front will sag just southeast of KY during the day Friday, and remain in close enough proximity for an ongoing potential of precip on Friday, including some continuing thunder chances near the TN and VA borders. Loss of remaining instability overnight will cut off thunder chances by Friday night. Meanwhile, low pressure will be taking shape over the southern plains on Friday as well. This will be in response to an upper level wave (emanating from the upper low currently off the Pacific Northwest coast) moving southeast toward that region. The low pressure system will track eastward and draw the frontal boundary back north as a warm front toward far southern KY Friday night and Saturday. The GFS has remained further south with the eventual low track since yesterday, and is similar to the ECMWF which has remained nearly steady. This track takes the low near the KY/TN border, resulting in a wet start to the weekend, with a temperature contrast across the JKL forecast area. Rain is a good bet everywhere on Saturday. Thunderstorms will also be possible near the passing low, with surface based instability possible in far southern KY, and elevated instability further north. Heavy rainfall could be a concern, with 6 hour QPF values between 0.75 and 1 inch, and locally higher amounts possible. Latest trends show highest rainfall occurring along the far eastern KY border Sunday night. Significant rain should then pull out with the departing low by Sunday, but some light rain could linger. Ridging at all levels then builds in on Sunday night and brings decreasing clouds, with fair weather lasting through the rest of the period. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) ISSUED AT 755 PM EDT WED APR 19 2017 Isolated to scattered showers and thunderstorms will gradually diminish across the area through midnight. Will maintain a few hours of VCTS at places south of I-64. Fog will be a concern tonight, especially at locations that have seen recent rainfall. This includes JKL and LOZ. Think that JKL will have more of a temporary affect from the fog early on, before southerly winds mix it out during the overnight hours. LOZ will likely drop down closer towards dawn, and have included some MVFR visibility restrictions there. Elsewhere, will keep out the mention for now. Once the fog burns off by the mid-morning hours, expect mainly VFR conditions to prevail. Any developing convection by the afternoon looks to be isolated, so will keep the mention of showers or thunderstorms out of the TAFs at this point. Light winds generally out of the south through the overnight will increase and become more southwesterly at near 10 kts by the mid- morning hours on Thursday, with some gusts in the 15 to 20 kt range by late morning. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...RAY LONG TERM...JMW AVIATION...GEOGERIAN is the U.S. government's official web portal to all federal, state and local government web resources and services.