498 FXUS63 KLMK 062352 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 752 PM EDT Wed Oct 6 2021 ...Updated Aviation Discussion... .Short Term...(This evening through Thursday) Issued at 305 PM EDT Wed Oct 6 2021 GOES-16 Water Vapor shows stunning imagery of the upper low now located over MO/AR with convection firing up along a N-S line from central AL into central TN. Latest surface analysis places a low center almost directly below the upper low over the MO/AR border with a warm front extending NE across southern IL/IN/OH. With our position on the eastern side of the low, deep southerly flow will continue to pump moisture rich Gulf air over the region resulting in above normal PWATs around 1.60 inches and dew points in the upper 60s. With that said, expect a chance of showers and thunderstorms to continue through Thursday night. Regarding thunderstorms, mesoanalysis shows an instability axis across western KY with SBCAPE values around 1500 J/kg. More concerning is the axis of higher shear values extending northward into central KY with effective bulk shear values 25-30kt. Soundings show unidirectional wind profiles with modest mid level flow. Can't be ruled out that this could potentially split any stronger updrafts, with slight backing H5 winds suggesting some left moving storms. But with freezing levels around 12kft and saturated columns, not expecting severe hail. There is some near severe wind gust potential, especially in our SW counties, where higher DCAPE values exist. There is also a low end threat for a brief spin up tornado in any stronger storms. As a result, SPC does have a Marginal Risk over our CWA west of I-75. Showers and cloudy skies will make for another mild morning with lows in the low to mid 60s. Thursday morning will see a mixed bag of weather including showers, drizzle, patchy fog, and possible thunderstorms. Showers and storm chances will continue throughout the day Thursday as the upper low slowly makes its way into IL. With these continuing showers and storms, there are minor flooding concerns, but current flash flood guidance and QPF lean more toward nuisance flooding of typically prone areas so no Flood Watch is being considered at this time. .Long Term...(Thursday night through Wednesday) Issued at 320 PM EDT Wed Oct 6 2021 Thursday Night - Friday... The closed upper low will move from the mid Mississippi River Valley up into the Great Lakes to end the work week, transitioning to an open wave as it does so. We'll hang on to some lingering showers Thursday night into Friday as the system departs our area, but overall things will trend drier from the previous 24 hours. Look for lows in the upper 50s and low 60s Thursday night, and highs just above normal in the mid to upper 70s on Friday. Friday Night - Monday... A strengthening upper ridge axis will build into our area over the weekend, stretching from Mexico northeastward into the lower Great Lakes. This will bring a return to dry conditions and temperatures warming back into the upper 70s and low 80s on Saturday, and into the low to mid 80s by Sunday. This would be about 10 degrees above normal for this time of year. The warm and dry conditions will likely persist into Monday as the upper ridge tries to hold on ahead of a digging negative tilt shortwave into the mid Mississippi River Valley. We'll continue to advertise dry conditions with temps mostly in the low 80s. Monday Night - Wednesday... It is entirely possible that the early to mid week time frame also stays dry or mostly dry and warmer than normal as a good amount of the data keeps the upper ridge established enough over our area. The forecast will mostly reflect that and will only have some smaller chances across our western CWA to account for the shortwaves passing to our NW. && .Aviation...(00Z TAF Issuance) Issued at 750 PM EDT Wed Oct 6 2021 IMPACTS: Periods of IFR/MVFR CIG/VIS in showers and thunderstorms. Potential IFR CIGs Thursday morning. Continued periodic MVFR conditions in showers and thunderstorms into Thursday afternoon. DISCUSSION: Current radar imagery shows area of thunderstorms approaching KLEX, with frequent lightning and brief torrential rainfall expected. Scattered showers and storms will continue to be possible across the area into Thursday, with brief reductions in CIGs and VIS into IFR range possible in heavier showers/storms. Additionally, expect CIGs to lower into low-end MVFR range and potentially IFR towards sunrise Thursday morning then gradually lifting through the afternoon. Outside of storms, winds will generally be out of the E/SE below 10 kts overnight then shifting more southerly Thursday afternoon. CONFIDENCE: Medium on timing and conditions. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Short Term...CG Long Term...BJS Aviation...JML