Area Forecast Discussion
Issued by NWS Jackson, KY

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998 FXUS63 KJKL 240317 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1117 PM EDT Sun Jul 23 2017 .UPDATE...
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Issued at 1117 PM EDT SUN JUL 23 2017 Thunderstorms have pushed southeast into Tennessee, with only a few rogue showers and storms currently dotting portions of far southeastern Kentucky. These should exit before midnight, with generally dry weather expected the rest of the night, as deeper moisture has exited. Winds have stayed up enough thus far; however, given the clearing upstream, and plenty of rainfall having occurred along the Cumberland Valley, have played up the fog for the rest of the night. Updates have been sent. UPDATE Issued at 706 PM EDT SUN JUL 23 2017 Freshened up the POPs through tonight based on the latest radar and higher resolution model guidance trends. The best instability gradient has been shifting slightly towards the Tennessee/Kentucky border with time, with more sustained convection aligning from north central Tennessee to southwest Tennessee. Scattered convection has initiated across portions of the Cumberland Valley in the last 15 minutes or so, and will continue to advertise the highest POPs down in this area. Did tighten up the gradient of POPs more so to the north, where the last few runs of the HRRR has been suggesting more limited activity through this evening. Updates will be out shortly.
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&& .SHORT TERM...(This evening through Monday night) Issued at 401 PM EDT SUN JUL 23 2017 MCV crossing east Kentucky into West Virginia has really zapped our instability today. We really don`t see much CU out there. There is a dewpoint/ouflow boundary draped across our far south, near Middlesboro, where instability is much higher to the south of this boundary. This would likely be the best area to see development this evening as dewpoints have remained in the mid to upper 60s back to the north. Temperatures have also remained a bit cooler today to the north. All of this together has really weakened the threat of storms for much of the area. With this in mind, have opted to drop the flash flood watch for the northern counties. Best rain chances will remain in the south closer to that boundary this evening. Should see activity diminish quickly by mid to late evening with dry weather expected overnight. With more clearing expected tonight, we could see a good deal of valley fog tonight. The cold front to the north will drop south tomorrow afternoon/evening and may allow a few showers or storms to pop up along the boundary at that time. Instability is rather weak, but given the middle of the afternoon, can`t rule out an isolated storm. As the cold front sinks to the south tomorrow evening, dry weather will be seen through Monday night. We may see another round of valley fog Monday night pending cloud cover. .LONG TERM...(Tuesday through Sunday) Issued at 440 PM EDT SUN JUL 23 2017 At the start of the period, a shortwave trough is expected to be moving through the Northeast and Mid Atlantic states with an upper level ridge centered over the Southern Plains region. Height rises At the surface, a boundary should continue pushing south of the area with high pressure expected to be centered across the Great Lakes region and Ontario and building into the region. A period of height rises should continue into the start of the period as well. Mid to upper level as well as surface high pressure centered north or northeast of the area is expected to dominate through midweek. The GFS is drier Tuesday into Wednesday compared to the recent ECWMF runs though the 12Z ECMWF has trended drier. With high pressure dominating, generally dry weather is expected for Tuesday into Wednesday though the cap may be weaker near the VA border and a slight chances right along the VA was used each afternoon. Temperatures will be near to slightly above normal on both days with with highs in the 80s on Tuesday and upper 80s to near 90 on Wednesday. Lows will be a bit lower than recent nights on Tuesday night in the mid 60s. The high, however, should move east of the area by late Wed into Wed night, with the boundary that will have stalled south of the area lifting north as a warm front by late Wed and Wed night and leading to increase in dewpoints and humidity. Models continue to indicate a low pressure system moving across central to eastern Canada during the middle to end of the week. An associated cold front should drop south of the Great Lakes and to the OH River on Thursday night. Models continue to indicate the boundary should move south across the area on Friday in advance of a shortwave trough. This boundary should continue to push south of the area Friday night into Saturday. Once the axis of the shortwave trough moves through on Saturday, height rises should occur by the second half of next weekend, with high pressure building toward the area. With the approaching front and shortwave trough more organized convection is expected from Thursday afternoon through Friday evening. Until the shortwave trough axis moves south and east, isolated convection cannot be ruled out over the weekend. Model runs vary with timing this and this will ultimately determine if next weekend ends on a dry note. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 841 PM EDT SUN JUL 23 2017 A broken line of convection has aligned along the Cumberland Valley this evening, but this looks to stay south of the TAF sites. Some isolated convection may threaten the area over the next few hours, and have maintained VCTS. An upper level disturbance will swing through the Ohio Valley tonight, perhaps sustaining some cloud cover. As such, have only allowed for a window of MVFR fog at SME and LOZ. Should more clearing take place, then the potential for more dense fog will increase. Most fog will burn off by 13z, with a return to VFR conditions. Winds will average around 5 kts or less, mainly out of the west southwest. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...KAS LONG TERM...JP AVIATION...GEOGERIAN is the U.S. government's official web portal to all federal, state and local government web resources and services.