Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 231848 AFDJKL Area Forecast Discussion National Weather Service Jackson KY 248 PM EDT TUE AUG 23 2016 .SHORT TERM...
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(This evening through Wednesday night) Issued at 248 PM EDT TUE AUG 23 2016 Strong surface ridge remains to our east this afternoon with moisture surging back northward across the lower and mid Mississippi river valley on the western flank of this high. As the high continues to slowly shift eastward tonight and especially Wednesday, this moisture will eventually pivot back into eastern Kentucky with the humidity on the increase. A band of mid level clouds will work east early Wednesday morning. While activity should be sparse with this moisture, there could be just enough lift to spark off a few sprinkles. As the day wears on...low level moisture should start to increase and this could aid in a shower or two along the high terrain of Tennessee and Virginia and could sneak just far enough north for a shower to develop in southern Kentucky. This shouldn`t be a big deal as widespread forcing is absent during the day. Tomorrow night is a bit more uncertain as it looks like we may have to watch how things unfold upstream as we could see convection morph into a MCS and drop east and south into the area overnight. Right now, opted to keep pops low with such uncertainty on where convection will develop and ultimately track...but it does appear the best chances to see some rain would be along or north of I-64. Temperatures will turn a bit milder tonight through Wednesday night as dewpoints creep upward, and a more humid airmass takes over. Lows tonight will remain in the 60s, with readings around 70 by tomorrow night. Highs on Wednesday will climb into the mid 80s, despite the increase in cloud cover. .LONG TERM...(Wednesday night through Monday) Issued at 349 AM EDT TUE AUG 23 2016 The long term period is expected to begin with an upper level ridge of high pressure centered over the Southeastern States while a somewhat broad trough is expected to extend south through portions of the Rockies and Plains States from an upper low moving east near the US/Canadian border centered over southern Manitoba. Surface high pressure that has brought a reprieve from the humidity is expected be departing the Northeast at that point. Return flow between this high and a cold front advancing toward the Great Lakes and MS Valley ushering deeper moisture back into the Commonwealth. PW is projected to have increased into at least the 1.5 to 1.75 inch range by the start of the period. In addition, a few disturbances should also be moving around the ridge at that point. From Wednesday night into Friday, the upper low is expected to move into and across Ontario and Quebec and 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 ridging across the Southeast is expected to build north and east and be centered over the Central or Southern Appalachians by Friday evening. This will lead to the cold front becoming increasingly sheared with time and probably more diffuse as well as it drops south of the Ohio River. It should usher in a minimally drier airmass for the start of the weekend. During the period of increasing moisture from Wednesday night into Friday followed by the approach of the cold front convection will be possible. However, mid and upper level forcing should be minimal if not lacking much of the time. Thus only isolated to scattered pops continue to be forecast during the Wednesday night to Thursday period. Although nocturnal convection will be possible on Wednesday night as a weak disturbance passes, loss of daytime heating should lead to a dry or mostly dry period on Thursday night. Even with the front progged to move across the area on Friday the proximity of the center of the upper level ridge and or height rises should keep coverage mainly isolated. Upper 80s should be common for highs during this period with some of the warmer spots or more southern valley locations reaching or exceeding 90. Overnight lows will return to the upper 60s to lower 70s. Surface and upper level ridging should remain dominant over the weekend and into the start of next week. There remains uncertainty as to how close the center of the ridge will be to Eastern KY during this period. The past couple of ECMWF runs have higher heights from Friday evening into Saturday night, while the GFS and the previous ECMWF run have higher heights at the end of the period compared to the 0Z ECMWF run. 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 each day. This would appear most likely over or near the higher terrain near the VA border to start the period. Then as the ridge possibly weakens or becomes centered further from the area, the cap possibly could be broken across more of the area on Monday. A warm and moist airmass will be across the region in any case with dewpoints expected to be in the upper 60s to lower 70s and 850 mb temps around 19C to 20C should keep temperatures in the upper 80s to around 90 for highs with overnight lows in the upper 60s to around 70 degree range. Heat indices should reach the 90s each day in many locations.
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&& .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) ISSUED AT 151 PM EDT TUE AUG 23 2016 VFR conditions will continue through the TAF forecast period. Some mid level cloud cover will be seen late tonight into early Wednesday, but only a few sprinkles are possible during this time. Winds will remain fairly light. && .JKL Watches/Warnings/Advisories... None. && $$ SHORT TERM...KAS LONG TERM...JP AVIATION...KAS

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