Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 210555 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED National Weather Service Jackson KY 1255 AM EST Wed Feb 21 2018 .UPDATE...
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Issued at 1240 AM EST WED FEB 21 2018 Updated the grids in the near term mainly to adjust sky cover and to tweak the temperatures and dewpoints per the latest obs and trends - capturing the ongoing ridge to valley temp split in the far east with more uniformly warm readings to the west. These have been sent to the NDFD and web servers. UPDATE Issued at 1022 PM EST TUE FEB 20 2018 The latest surface analysis shows the cold front remains west of the region with return flow keeping most locations mixed. The southerly flow is also keeping a good mix of clouds across eastern Kentucky tonight with best concentration of mid level clouds across the Cumberland Valley region. Only minor adjustments were needed to account for the latest obs and trends. UPDATE Issued at 718 PM EST TUE FEB 20 2018 We have seen a decrease in the winds early this evening and therefore the Lake Wind Advisory was cancelled early. The latest satellite trends have indicated some mid to high level clouds will continue to stream across eastern Kentucky under general south to southwest flow. Updated the forecast to account for the clouds and winds, but otherwise the forecast was in good shape this evening.
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&& .SHORT TERM...(This evening through Wednesday night) Issued at 303 PM EST TUE FEB 20 2018 Impressive height anomalies over eastern Kentucky has led to record breaking high temperatures today. We have in fact set the all time record high for Jackson for February, with London likely to fall just a few degrees short. Gusty southwest winds continue to crank across the area with wind gusts up to 35 mph still likely occurring in our northern and western zones. Plan to let the lake wind advisory continue through the evening hours. With clear skies in place, we should see temperatures in the eastern valleys drop quickly as they decouple. Skies could stay mostly clear through a good chunk of the night, allowing lows in the eastern valleys to dip well into the 50s. Our western areas could stay fairly mixed tonight given the stronger gradient to the west. A cold front will work east across the Ohio river valley tonight into Wednesday and Wednesday night. Showers will be ongoing along the front throughout the period. As the front pushes east and southeast, the forcing along the front will be weak through Wednesday. However, enough convergence should be present to allow for good rain chances for most of the area. A shortwave riding northeast across the region may provide an uptick along the front late Wednesday night. While there will be instability developing Wednesday afternoon, model guidance is suggesting the better thunder chances may be Wednesday night with the shortwave providing some added lift. Models are likely overplaying dewpoints on Wednesday, accounting for the surface instability. Rain amounts through Wednesday night should remain under an inch and fairly spread out. Thus, no plans for any flood watches for our area. .LONG TERM...(Thursday through Tuesday) Issued at 501 PM EST TUE FEB 20 2018 The first several days of the period still look like a very wet time due to frontal boundary oscillating over the region. It will be in the process of slowly passing through as a cold front on Thursday, with rain expected. The front is expected to stall to our south with a brief break in precip likely on Thursday night. However, it will turn around as a warm front and should be heading back north through the area by Friday morning with at least a potential for more rain. A relative lull in precip is expected from late Friday into Friday night while we reside in the warm sector in between frontal waves. Friday night into Saturday another wave is expected to move along the front with an enhancement of precip. Current indications are that the heaviest will be just to our north. A more substantial low pressure system will develop on the front and track northeast through the Midwest Saturday night. This will bring still more rain, but will finally give the front a definitive push through the area as a cold front and allow high pressure to build in with drier air to start the new week. A couple of other issues to be considered during the period include the potential for thunder and excessive rain. In terms of thunder, some very weak deep instability was present in models at times, but looked very marginal for thunderstorm support. Even though the most unstable levels supported negative lifted indices for parcels rising to 500 mb, the 500 mb temperatures were warmer than -20C, with weak lapse rates above, making it questionable if convective parcels would reach the magic -20C. In terms of precip amounts, we may eventually have some problems. The heaviest precip for the JKL forecast area is likely to be Friday night into the weekend. It is still unclear where the axis of heaviest rain will be, and model changes can still be expected before the event arrives. Depending on the model depictions in the next couple of days, the situation may need to be addressed with products beyond the daily routine. && .AVIATION...
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(For the 06Z TAFS through 06Z Wednesday night) ISSUED AT 1255 AM EST WED FEB 21 2018 The TAFs will remain VFR through the night, before lower CIGs advect southeast later this morning and into the afternoon. Right now will keep this MVFR for most sites during the day, but following sunset, expect lower cigs to develop for all the sites from northwest to southeast. A stalling front dropping into the area from the northwest will bring showers into the forecast area starting later this morning and continuing into the afternoon. This could also lead to brief lowering of CIGs and VIS in heavier showers or a stray thunderstorm - kept VCTS out of the TAFs for now owing to limited instability. The winds will also gust 15 to 20 knots ahead of the boundary. Before then, though, LLWS will again plague the area with winds off the sfc at 40 to 45 kts from the south southwest through 14z or so.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...KAS LONG TERM...HAL AVIATION...GREIF

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