Area Forecast Discussion
Issued by NWS Jackson, KY

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948 FXUS63 KJKL 240824 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 424 AM EDT WED AUG 24 2016 .SHORT TERM...(Today through Thursday) Issued at 352 AM EDT WED AUG 24 2016 Moisture continues to increase across the region this morning with west to southwest flow in place at the surface up to mid/upper levels. This has allowed mid and high level clouds to increase in coverage and dew points to rise towards the mid 60s. Luckily, this increase in cloud cover has kept most fog development at bay early this morning. While shower activity should be sparse today, there may be just enough moisture and lift to spark off a few showers this afternoon. This shouldn`t be a big deal as widespread mid and upper level forcing is absent during the day. On Thursday, a cold front extending from a surface low along the United States/Canadian border, will shift towards the Ohio Valley. The front will attempt to cross into Kentucky but is expected to weaken and fall apart as it runs into a dominate upper ridge in place over the southeastern CONUS. In fact, the upper ridge is expected to reinforce itself over Kentucky Thursday afternoon, limiting any shower activity to the northern and eastern counties during the morning hours. Skies will begin to clear Thursday afternoon/evening as surface high pressure builds back into the Ohio Valley. Temperatures will warm into the upper 80s today and tomorrow, with some locations hitting that 90 degree mark on Thursday. Humidity will also be higher, making for more muggy and uncomfortable conditions through the short term. .LONG TERM...(Thursday night through Tuesday) Issued at 420 AM EDT WED AUG 24 2016 The long term period is expected to begin with an upper level ridge of high pressure centered over the Southeastern States while a weakening upper level low and associated shortwave trough is expected to be nearing the Western Great Lakes. At the surface an area of low pressure will be moving from Ontario into Quebec, with a cold front trailing south and southwest into the Great Lakes, Mid MS Valley and on into the Plains. A ridge of high pressure should extend from the Southeastern States to off the Northeast US Coast with the boundary separating this high from another sfc high centered over the Plaisn and Rockies. From Thursday night into Friday, the upper low is weaken to an open wave and approach the Canadian Maritimes by Friday evening. Meanwhile the associated surface low will also move east from Ontario and toward the Maritimes during the period. However, the mid and upper level ridging across the Southeast is expected to build north and east and be centered near the Blue Ridge Region of VA and NC by the end of the period. The shortwave weakening and shearing to the north and east and the ridging over the Southeast will lead to the cold front becoming increasingly sheared likely more diffuse as well with time as it drops south of the Ohio River on Friday. It should usher in a very minimally drier airmass for the start of the weekend. With the approach of the cold front and a moist airmass in place, cumulus should develop during peak heating along with a few showers and thunderstorms. Even with the front progged to move across the area on Friday, lack of mid level forcing and the proximity of the center of the upper level ridge and some height rises, coverage should be isolated. Upper 80s to lower 90s are expected for highs outside of the high terrain on Friday. Dewpoints mainly in the lower 70s should yield heat indices well into the 90s and a couple of spots might touch a heat index of 100 briefly. Surface and upper level ridging should remain dominant over the weekend and into the first half of next week. During this time, an upper level low or shortwave trough should move from the Plains to the Great Lakes and then across Southern Canada and the Northeast US toward the end of the period. This pattern should also send a boundary south and east across the Great Lakes and into the Northeast US. However, as this boundary nears the OH River the persistent ridging should slow it down or stall it out north of the area. There does remains some model variability as to how close the center of the ridge will be to Eastern KY over the weekend along with variability in the magnitude of 500 mb heights with it and timing differences with the trough passing by to our north and west over the weekend into early next week. Of note, but of no affect to Eastern KY through the end of the Long Term period is a possible tropical system moving into the Gulf of Mexico by Monday or Tuesday as it works around the Southern Periphery of the Southeastern/ Southern US ridging. Nevertheless, this pattern should keep the summer time heat and humidity in place over the weekend and through the end of the period. The airmass should be moist enough for at least diurnally driven cumulus each day, with some of this possibly able to break the cap in a few locations. This would appear most probable over or near the higher terrain near the VA border over the weekend, and then as the ridge weakens and becomes centered further from the area, possible across more of the area from Monday into Tuesday. Slightly better chances for convection will be across the north on Tuesday closer to an approaching boundary. High temperatures averaging in the upper 80s to lower 90s for highs with overnight lows around 70 are expected over the weekend and into the start of next week. Heat indices should reach the 90s each day and possibly near 100 in a few locations. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 140 AM EDT WED AUG 24 2016 With surface high pressure now off to our east, moisture has begun returning to East Kentucky. This is evident with the increase in mid to high level clouds early this morning. However, no aviation impacts are anticipated through the period other than some patchy fog potential in the deepest valleys and near bodies of water. Winds will be light and variable through the period. && .JKL Watches/Warnings/Advisories... None. && $$ SHORT TERM...JVM LONG TERM...JP AVIATION...JVM

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