617 FXUS63 KLMK 161909 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 309 PM EDT Thu May 16 2024 .KEY MESSAGES... * Widespread showers and storms Friday and Saturday, with locally heavy rain possible Friday morning. * Drier Sunday and Monday with well above normal temperatures. * Showers and storms return Tuesday and Wednesday. && .SHORT TERM /THROUGH FRIDAY/... Issued at 309 PM EDT Thu May 16 2024 We will remain under the influence of a split flow aloft as we end the week. The northern stream will work a shortwave trough out of the Upper Midwest and through the Great Lakes tonight into tomorrow. This will slowly push a weak sfc cold front currently over the Upper Mississippi Valley into the Wabash Valley/Ohio Valley by tomorrow morning. Mesoanalysis this afternoon shows an axis of strong moisture advection stretching from Mississippi Delta into central IL with PWATS of around 1.50" located over the Missouri Bootheel. Radar mosaic over the region shows an area of showers/storms ahead of the sfc boundary over central IL working to the east-northeast. While most of our area will remain under the influence of weak sfc high pressure this afternoon into the early evening, isolated shower or thunderstorm is possible this afternoon, mainly across southern IN along the I-64 corridor and west of I-65. Mid-level vort max associated with the southern stream, will eject out of eastern TX and meet up with the northern stream trough axis along the Ohio River later tonight into early tomorrow morning. A 30- 35kt low-level 850mb jet along the trough axis will help provide additional lift for elevated showers and thunderstorms initially for southern IN and north central KY after midnight towards daybreak tomorrow. The southern vort max arrives by 10-12z tomorrow morning increasing showers and storms further south across the KY/TN border. Showers and storms become more scattered towards the afternoon as the vort energy quickly works east northeast later morning/early afternoon. Main impact from these showers/storms will be heavy rain that could lead to localized flooding. Excessive rain outlook from WPC continues to highlight areas west and along I-65 in KY in a slight risk for flash flooding. Forecast QPF amounts for tonight into tomorrow ranges from 0.75" to a little over an inch while current 1 hour FFG is around 1.50". As for the severe threat, I agree with the current day 2 outlook from the SPC with a general thunder over central KY. Model soundings have limited instability as the best dynamics will be focused over the southern US. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Issued at 309 PM EDT Thu May 16 2024 Positively tilted upper trof will slowly lift out of the Red River Valley beginning Friday night, but the emphasis is on slowly, as it will take its sweet time and only reach the southern Appalachians by Sunday. Unsettled weather will prevail for at least the first half of the weekend, with PWATs around 1.5 inches through at least late Saturday. Brief heavy downpours and localized flooding will be the main hazards. Mid-level winds and deep-layer shear are maximized Friday evening, but very weak lapse rates will preclude potential severe wx. Also a decent amount of bust potential on Saturday as, at some point, the upper trof axis will slip to our east, but the cyclonic curvature in the flow does not lend any confidence to a dry forecast. Showers may linger east of Interstate 65 Sunday as the system slowly pulls away, but overall it's looking drier for Sunday-Monday in our position between systems to our east and west. Temps turn quite warm under shortwave upper ridging. Could see another day of unseasonable warmth on Tuesday as the next incoming system is trending a bit slower. Best chance for showers and storms is Tuesday night and Wednesday, and while this activity could become more organized, any threats are still very conditional at 6 days out. && .AVIATION /18Z TAFS THROUGH 00Z SATURDAY/... Issued at 117 PM EDT Thu May 16 2024 Low stratus hung on longer than expected especially from LEX-RGA-BWG but current visible satellite imagery shows clouds have started to mix and clear out. While VFR conditions will remain through the forecast period, increasing mid/upper clouds along with rain and even some storm chances are in the forecast especially overnight into tomorrow morning. Mid-level wave coming out of TX will work into the Ohio Valley overnight into tomorrow morning. Models show an area of showers/storms working across our area in the predawn hours. Bulk of the heaviest rain/storms could occur tomorrow morning before a lot of the shower activity with isolated storms develop tomorrow afternoon. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...BTN LONG TERM...RAS AVIATION...BTN