815 FXUS63 KLMK 111008 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 608 AM EDT Thu Oct 11 2018 ...Updated Aviation Discussion... .Short Term...(This afternoon through Friday) Issued at 311 AM EDT Thu Oct 11 2018 The much anticipated cold front is currently working its way through the region this morning, ushering in much cooler and drier air behind it. Winds have been a little gusty at times, and expect them to remain gusty through the rest of morning and afternoon. Models have been handling cloud cover poorly across parts of MO/IL/IN today, and basically have little in the way of clouds over areas that are currently socked in with stratus. This is important because all of those clouds will be moving into the region over the next several hours. Believe the models are underplaying the amount of post-frontal moisture trapped within the boundary layer, which could result in clouds sticking around through a good portion of the day in our neck of the woods. Think that by late afternoon there should be enough dry air mixed into the boundary layer that we see the stratus disperse and give way to clear skies. Winds will gradually die down this evening and overnight as the boundary layer decouples and an inversion sets in. The clear skies, dry air, and light winds will allow temperatures to drop to their coldest values of the season. Expect many areas tomorrow morning to fall into the upper 30s and low 40s, with perhaps a few mid 30s in some of the cooler valleys and low lying areas. There is some potential for patchy frost, mainly in southern Indiana tomorrow morning, but conditions for widespread frost look marginal. Therefore, no frost advisory is planned at this time. && .Long Term...(Friday through Wednesday) Issued at 255 AM EDT Thu Oct 11 2018 A shortwave trough will pass overhead Friday night. The bulk of the moisture associated with it Friday afternoon and evening will be manifested in mid and high clouds with drier air at lower levels thanks to Canadian high pressure building in at the surface. However, some patchy light rain will probably make it to the ground with QPF on the order of a tenth of an inch. Then the surface high and weak shortwave ridging aloft will take over for a dry day Saturday and into Saturday night. Sunday low pressure north of the Great Lakes will pull a cold front and its associated showers into the region. Remnants of former Pacific Hurricane Sergio coming in from the WSW may help to anchor the southern part of the front and keep shower chances going in the forecast into Monday. An upper trof approaching from the northwest early next week may prolong shower chances into Monday night and possibly Tuesday. Little if any thunder is expected. The best chance will be a few rumbles on Monday in southern Kentucky. The spreads among the GEFS and ECMWF ensemble members are large, especially Sunday night into early next week. Run-to-run consistency has been lacking in model solutions recently for the outer periods of the long term. So, overall confidence is low Sunday through Wednesday, but the big picture is that we can expect unsettled weather with occasional shower chances. With the forecast leaning toward more clouds and frequent passage of disturbances, have dialed back the frost chances compared to the forecast from yesterday at this time. Right now the best chance for any frost looks to be Tuesday morning but, again, confidence is low. && .Aviation...(12Z TAF Issuance) Issued at 602 AM EDT Thu Oct 11 2018 With the cold front pushing into eastern KY at this hour, the region is under a post-frontal regime where boundary layer moisture remains trapped under a strong inversion. This setup has allowed widespread MVFR stratus to move in from the northwest, and could persist through much of the day. Most model guidance continues to handle the stratus and boundary layer moisture poorly, so confidence in the duration of the cloud cover late this morning into the afternoon remains low. With enough daytime heating, would expect the stratus to rise to low-end VFR by early afternoon across most sites. Drier air should eventually mix into the boundary layer and scour out the stratus, leading to clear skies overnight. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Short Term...DM Long Term...13 Aviation...DM