682 FXUS63 KLMK 130600 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 200 AM EDT Wed Mar 13 2019 .Short Term...(This evening through Wednesday) Issued at 305 PM EDT Tue Mar 12 2019 Sfc high pressure over the Upper Ohio Valley will maintain its grip overnight, but changes will be underway as the upper pattern amplifies ahead of a strong low over the Desert Southwest. Developing warm advection may set up just enough isentropic lift to support a few light showers across southern Indiana overnight, but will limit that to north of a line from Jasper to Madison. Southerly flow will increase through the day Wednesday as the gradient tightens. Winds will pick up to 15-20 mph in the afternoon with some gusts approaching 30 mph, mainly west of I-65. Bigger sensible wx impact will be temps, which will push 70 degrees in spite of a respectable cirrus shield filtering out much of the available sunshine. .Long Term...(Wednesday night through Tuesday) Issued at 250 PM EDT Tue Mar 12 2019 A line of showers and embedded storms will be just entering Western Kentucky by Wednesday evening, and eventually rolling through southern Indiana and central Kentucky by early Thursday morning. Models indicate a general weakening trend with this line as it progresses eastward, with it falling apart considerably, if not altogether, by the time it reaches the I-65 corridor. As has been mentioned in previous discussions, instability ahead of and long the line of precipitation looks to be minimal, and at this time would not anticipate any strong/severe convection in our region with it. A plume of low level moisture associated with a Theta-E ridge will move into the region late Thursday morning and afternoon. Around the same time, low to mid level lapse rates will begin to slightly steepen in response to an approaching broad, strong upper level low. The combination of low level moisture and marginal lapse rates could result in some instability developing by afternoon, and an approaching cold front from the west will serve as a lifting mechanism for convective initiation. We're just now starting to come into range of some high-res models (like the 3km NAM), which show a narrow line of showers/storms developing along this front late Thursday afternoon in far western KY and southern IL before moving into our region. With strong shear in place, storm severity will be conditional on the amount of instability that develops, which at this time looks to be minimal. If we happen to get some clearing in between clouds/showers and some steepening of low level lapse rates, it's possible we could see enough instability to sustain severe storms. The main threat with any severe storms would be straight line winds, though an isolated tornado would be possible due to strong low level shear and storm relative helicity. Given how fast storm motions will be, and the overall areal coverage and propagation of the line, think the flooding threat will be small, though heavy rainfall could result in some localized issues if some storm training occurs. Strong gradient winds will also be likely outside of storms Thursday. While overall trends in surface wind gusts have come down over the past couple of days due to increased clouds and less boundary layer mixing, it still looks like many locations could see gusts over 40mph. The cold front pushes through the region early Friday morning, ushering in some cooler temperatures. A couple of disturbances/fronts could impact the region Friday and late Sunday, bringing very low-chance PoPs to some. Otherwise, the rest of the weekend into early next week should remain dry. && .Aviation...(06Z TAF Issuance) Updated at 200 AM EDT Wed Mar 13 2019 VFR weather will continue early this morning and throughout the daytime period of Wednesday. A thicker band of mid-level clouds will continue to spread northeast across the area between now and 15z before lifting north. These clouds are associated with a warm front, and HNB could see a brief light shower as well. The bulk of the precipitation will remain off to the north of the TAF sites. As the previous discussion mentioned, marginal LLWS conditions will also be in place between 09-15z. 2 kft winds are forecast to increase to 30- 35 kts out of the SSW. After 15z, the focus will be on increasing winds down to the sfc. Southerly winds peaking this afternoon will gust to 25-30 kts at HNB/SDF/BWG with 20-25 kts likely at LEX. Winds off the surface will increase even more this evening and overnight as a powerful storm system tracks northeast across the central Plains. LLWS will be a factor by 00z. Some sporadic strong gusts at the sfc will still be possible after 03z as showers and decaying storms start to move in from the west. Showers could bring some brief vsby reductions early Thu. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Short Term...RAS Long Term...DM Aviation...EBW