Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 231354 AFDJKL AREA FORECAST DISCUSSION National Weather Service Jackson KY 954 AM EDT Sun Jul 23 2017 .UPDATE...
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Issued at 954 AM EDT SUN JUL 23 2017 After seeing the heavy rainfall from last night and looking the latest CAM runs from this morning which generally all show some redevelopment across the area this afternoon and evening, have opted to go with a flash flood watch for the northern half of our forecast area. Flash flood guidance is running much lower now with all the heavy rains that have moved through, so it won`t take much to cause more issues. The watch will be issued for mainly areas that saw rain overnight. Areas farther south, have more or less not seen as much rainfall, so guidance remains higher to the south. Latest HRRR really targets the same areas that got hit last night, so concern is clearly elevated. RAP targets areas a bit farther south, but will continue to monitor trends as the day goes on. Given the generally good agreement on the redevelopment, have gone above guidance on the rain chances this afternoon and evening. UPDATE Issued at 740 AM EDT SUN JUL 23 2017 Latest round of storms are exiting far eastern Kentucky. This will set up a lull before the next batch moves in or develops over the area. Have updated the grids with this in mind as well as adding in the latest T/Td obs and trends. These have been sent to the NDFD and web servers.
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&& .SHORT TERM...(Today through Monday) Issued at 420 AM EDT SUN JUL 23 2017 07z sfc analysis shows a washed out front lying through the lower part of the Ohio Valley. This night a series of storm clusters are moving generally east along this boundary with outflows from these storms making it south deep into the JKL CWA. The core of the strongest storms, and biggest threat for damaging wind gusts and flooding rains, will be with the main track through northern parts of Kentucky, but additional strong storms, though more scattered, will be possible south. Fleming County has borne the brunt of the storms for the JKL CWA, so far, with reports of wind damage and flooding there early this morning. As the first cluster of storms fade out over far eastern Kentucky, the next is poised to enter from the west. This could bring renewed flooding to the area as well as a threat for additional wind damage. Otherwise, temperatures and dewpoints vary across the area based on where the rain has fallen with both in the upper 60s north and the south seeing temps in the low to mid 70s with low 70s dewpoints. Winds outside of the storms and outflows have been generally from the south to southwest at 5 to 10 mph. The models are in good agreement on the broad details aloft with the pattern through the short term portion of the forecast. However, the determinative factor for sensible weather will be from smaller scale waves poorly handled by the models so confidence is low in the specifics from any individual model. On a broader scale the models do all depict the fairly strong trough that will move through the Great Lakes and Ohio Valley today with significant height falls and plenty of energy brushing by to the north. This northwest flow environment will maintain the threat for MCS activity through the day before the heights start to rebound in the trough`s wake later tonight and on Monday. Will favor a general model blend as a starting point but significantly lean on extrapolation of current radar trends and the HRRR for near term details. Sensible weather will feature continuing showers and thunderstorm threatening the area through the morning as the next cluster moves into the CWA. There remains enough instability in place with high PW air and some decent DCAPE available for downdrafts. Accordingly, strong storms will continue to threaten flooding rains and damaging winds at least through dawn. After that the frontal boundary and left over outflows will set the stage for more potential storms. The convection and clouds today will keep temperatures in check compared to the last few. This should mitigate the heat concerns even though dewpoints will continue to be high. High pressure will start to build into the area tonight but not effectively enough to push down dewpoints and PoPs too far. As a result, scattered storms will still be a concern tonight and Monday, though to a far lesser extend then this morning and most of the day. Used the CONSShort as a starting point for all the grids, though made some minor changes to point temps today and tonight. Did also make major adjustments to PoPs and QPF in the near term to better reflect radar trends. .LONG TERM...(Monday night through Saturday) Issued at 320 AM EDT SUN JUL 23 2017 The latest model data indicate that the remnants of a stalled out frontal boundary will linger across the northern Tennessee valley to being the extended period. As moisture interacts with this boundary, or at least what is left of it, isolated showers and storms are expected to form along it. The best chance for rain to begin the period should be Monday night, as the front drifts slowly southward across the region. A few showers and storms may move across portions of eastern Kentucky along the Tennessee border on Tuesday and Wednesday, as the front meanders northward toward the area. There should then be a break from the rain Wednesday night, as the front finally moves off well to our south. However, a second more well defined cold front is then forecast by the models to move across the Ohio and Tennessee valleys Friday night and Saturday. This front may be strong enough, and have enough moisture interacting with it, to produce numerous showers and storms across eastern Kentucky going into the weekend. Temperatures during the period should start out above normal, with readings in the upper 80s expected for Tuesday through Thursday. The temperatures should cool slightly after that, as the second cold front moves through. We should see high temperatures only making it into the lower 80s Friday and Saturday due to persistent widespread cloud cover and repeated rounds of showers and storms during that time. Nightly lows are forecast to start off in the mid to upper 60s, before cooling to the lower 60s by the end of the period. && .AVIATION...(For the 12Z TAFS through 12Z Monday morning) ISSUED AT 755 AM EDT SUN JUL 23 2017 The latest round of convection has moved off to the east of the TAF sites. Additional storms are possible through the afternoon. With any storm conditions would drop to MVFR or IFR. SME and LOZ may very well remain VFR through much of the period if convection does not make it that far south. The convections should be on the wane by evening with a bout of low clouds and fog possible late - but have not included this in the TAFs for now. Winds will generally be from the south to southwest at 5 to 10 kts today with some 20 knot gusts possible in the afternoon outside of any storms or outflow boundaries. && .JKL WATCHES/WARNINGS/ADVISORIES...
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Flash Flood Watch through this evening for KYZ044-050>052- 058>060-104-106>112-119-120.
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&& $$ UPDATE...KAS SHORT TERM...GREIF LONG TERM...AR AVIATION...GREIF

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