Area Forecast Discussion
Issued by NWS Jackson, KY

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472 FXUS63 KJKL 270320 AAA AFDJKL Area Forecast Discussion...UPDATED National Weather Service Jackson KY 1120 PM EDT FRI AUG 26 2016 .UPDATE...
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Issued at 1120 PM EDT FRI AUG 26 2016 The forecast is on track, just did a quick touch up to the T/TD and sky grids per the latest Obs and trends. These have been sent to the NDFD and web servers. UPDATE Issued at 740 PM EDT FRI AUG 26 2016 23z sfc analysis shows high pressure off to the northeast of Kentucky helping to keep the eastern part of the state dry while scattered thunderstorms are found on the fringes of this high. Warm and humid conditions continue with dry bulb temperatures in the upper 70s to mid 80s currently with dewpoints running in the low to mid 70s most places, yielding heat indices in the low to mid 90s. Winds are not much help with the heat this evening with the majority of observations light and variable. Meanwhile, skies are mostly clear through the region aside from storm clouds to the south and west of the area. Look for a similar night as last with mostly clear skies and muggy conditions. Patchy valley fog will be locally dense during the late night hours, but likely not quite as pervasive as last night/early this morning. Have updated the forecast to reflect this and also to tweak the near term T/Td grids per the latest ShortBlend guidance, obs, and trends. These updated grids have been sent to the NDFD and web servers.
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&& .SHORT TERM...(This evening through Saturday night) Issued at 331 PM EDT FRI AUG 26 2016 Upper level high pressure center continues to churn from the Appalachians into the Mid-Atlantic, with disturbances and associated storms riding around its western periphery from the Mid-Mississippi Valley into the Ohio Valley and Great Lakes. Weak surface ridging across the Ohio Valley and Great Lakes will keep light downslope flow in place, thus maintaining a relatively drier airmass across eastern Kentucky. Still seeing dewpoints in the mid 60s to low 70s, but this is lower than those in the low to mid 70s experienced yesterday. This afternoon`s cumulus field has therefore been more shallow and less vast in coverage, allowing temperatures to continue climbing through the upper 80s and into the lower 90s within the next hour or so. Clearing skies will then take place this evening. Expecting fog development to be less robust than what occurred last night given lower crossover temperatures with this afternoon`s lower dewpoints. Light downslope flow should preclude much in the way if any fog from occurring in the higher terrain of eastern Kentucky. Will likely still see patchy development, perhaps becoming dense at times, in a few of the typically fog-prone river valleys. Saturday should be largely a repeat of today, but will leave isolated storm mention in place across southeastern Kentucky into the Lake Cumberland region as a slight uptick in deep layer moisture occurs as aforementioned surface ridging to the north shifts east. Will continue to see shortwave perturbations move around the western periphery of the upper high, with a stronger wave expected to move through the northern Plains into the western Great Lakes. While forcing from this latter feature will be displaced well northwest of the Bluegrass, strong diabatic heating once again, evidenced by temperatures climbing into the low-mid 90s, combined with veering winds ushering in this slightly greater moisture could be enough to spark a shower or storm across the higher terrain. Most likely scenario is for convection to occur along the Cumberland Plateau and move north/northwest into the Lake Cumberland region during the mid-late afternoon. Without any real semblance of forcing aloft, any storm should remain shallow and of the pulse variety. Warm and humid conditions will then bring another night of patchy valley fog Saturday night into Sunday. .LONG TERM...(Sunday through Friday) Issued at 331 PM EDT FRI AUG 26 2016 The period will begin with a large ridge of high pressure parked off the southeastern CONUS. The flow around the western edge of the high will continue to bring warm and moist air off the western Gulf of Mexico into the Ohio and Tennessee valley regions. The warm and humid air mass that will be in place should provide enough energy to spark showers and storms across the area, particularly in our more rugged terrain, as it appears there will still be no well defined trigger available. The best chances for rain will be during the afternoon and evening hours during the period, with disorganized scattered convection expected at best. Temperatures will be hot and muggy to start things off, with daily highs in the lower 90s Sunday and Monday, and around 90 on Tuesday. Wednesday should be slightly cooler, as clouds and precipitation cool things off a bit. Highs on this day are forecast to be in the upper 80s for most locations. By Thursday we may even see a weak cold front move through from the north. This change in air mass would allow for even cooler readings, with highs on Thursday in the mid 80s on tap, with the warmest readings in our far south along the Tennessee border. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 800 PM EDT FRI AUG 26 2016 VFR conditions with light winds will persist through the rest of the evening at all sites. Then we will once again see some fog development, potentially becoming dense in some river valleys. Current thinking remains that terminals will see less of a threat for dense development given strong heating and lack of rain today, but persistence and nearby presence of weak surface ridging centered near the Great Lakes warrants maintaining at least some MVFR/IFR visibilities for now at LOZ/SME/SYM from approximately 8-13Z. Very light downslope flow should provide just enough subsidence to keep fog from reaching SJS/JKL. Dewpoints also mixed a tad lower early this afternoon, so crossover temperatures will have a little tougher time being reached, likely inhibiting widespread fog development. && .JKL Watches/Warnings/Advisories... None. && $$ UPDATE...GREIF SHORT TERM...GUSEMAN LONG TERM...AR AVIATION...GREIF/GUSEMAN

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