128 FXUS63 KLMK 100703 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 303 AM EDT Wed Oct 10 2018 .Short Term...(Today and tonight) Issued at 300 AM EDT Wed Oct 10 2018 Regional radars are beginning to pick up on some light echoes across parts of western Kentucky and the Tennessee Valley early this morning. Shower activity is expected to grow in coverage and eventually impact central KY and southern Indiana through much of the morning hours. Should see that activity push out of the region by early afternoon, with some partial clearing possible. Models indicate the atmosphere developing some weak instability in the afternoon, which could help contribute to some isolated to scattered showers/storms. The greater chance/coverage of precipitation will occur during the late afternoon to overnight timeframe ahead of a strong cold front moving in from the west. Instability ahead of the front continues to look weak, generally under 1000J/Kg, due to widespread cloud cover. Deep layer shear will be modest though (0-6km bulk shear 30-40kts), and could contribute to some organized storm structures should enough instability be realized. The current 06z Day 1 SPC Outlook highlights parts of southern Indiana and northern Kentucky in a marginal risk, which is where the best shear/instability will be co-located ahead of the front. Main threats with any strong to marginally severe storms will be gusty winds and small hail. Heavy rainfall will also be a threat in the stronger showers/storms, as PWATs remain high (~2") ahead of the cold front. Winds will switch quickly to the northwest behind the front tonight, and could be gusty at times. Much, much drier and cooler air will advect in from the northwest, ending the long streak of above normal temperatures we've experienced over the past couple of weeks. && .Long Term...(Thursday through Tuesday) Issued at 254 AM EDT Wed Oct 10 2018 After some lingering showers in the Blue Grass and Lake Cumberland regions Thursday morning, Canadian surface high pressure will build into the region and provide us with mostly dry weather through Saturday. The possible fly in the ointment will be a fairly sharp upper trough that will swing overhead Friday evening. The trough will primarily produce mid and high clouds with dry air in the low levels thanks to the surface high. However, some rain could make it to the ground so after coordinating with surrounding offices will include a slight chance of precipitation in conjunction with the upper disturbance. Friday morning low temperatures may dip briefly into the upper 30s north of I-64, and a few low, rural cold sinks in southern Indiana could see a bit of patchy light frost. Some very patchy, very light frost could form in southern Indiana on Saturday morning as well if the upper shortwave trough's mid/hi clouds can clear out enough by dawn. The Saturday night through Monday period is not being handled well by the models at all, and there is great uncertainty in the forecast. Generally speaking, though, an upper trough will sweep eastward from the upper Plains through the Great Lakes to the Northeast. Surface low pressure will cross Ontario and Quebec with a cold front trailing southwestward to another low crossing the southern U.S. This southern low may be remnants of former Pacific Hurricane Sergio, and will bring moisture along with it as it interacts with the front and moves through the mid-Mississippi and Ohio Valleys. The end result will be rain chances in the forecast for this time frame, with future forecasts hopefully being able to refine the timing. No thunder is expected. We should then dry out on Tuesday as the upper flow goes zonal and high pressure moves in at the surface. Patchy frost will again be possible Tuesday morning. && .Aviation...(06Z TAF Issuance) Issued at 120 AM EDT Wed Oct 10 2018 A 35-40kt LLJ is resulting in some low-end LLWS conditions across BWG/HNB this morning. Clouds and moisture are advecting into the region ahead of the LLJ, and we should see a round of showers affect the TAF sites this morning. MVFR to high-end IFR cigs/vis will be possible with these showers. Models indicate some clearing behind the showers this afternoon, though it will be short lived as a cold front approaches from the west and results in another round of showers and storms. IFR to MVFR cigs/vis will be possible with the stronger showers/storms this afternoon and evening. Winds will also be gusty at times out of the south through much of the day, and will quickly shift to the northwest behind the cold front tonight. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Short Term...DM Long Term...13 Aviation...DM