Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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024 FXUS63 KLMK 300120 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 920 PM EDT Mon Apr 29 2024 .KEY MESSAGES... * Showers and scattered thunderstorms will be possible later this afternoon before coming to an end tomorrow. * Dry and warm Midweek with highs in the mid to upper 80s * Additional showers and thunderstorms possible late in the week, though confidence in exact timing remains low. && .UPDATE... Issued at 919 PM EDT Mon Apr 29 2024 As the line of precipitation nears Interstate 65, we continue to see some cloud flashes of lightning, mainly along and south of the Kentucky parkways. A few ground strikes are occurring, but most of the lightning is staying in the clouds. Severe weather isn`t expected as the system moves east during the rest of the night. The forecast remains on track with only minor adjustments being made. && .SHORT TERM /THROUGH TUESDAY/... Issued at 808 PM EDT Mon Apr 29 2024 Currently, a low pressure system is over the Minnesota/Wisconsin border. To the south, a cold front extends from the surface low and runs through Chicago and sweeps to the southwest towards the Ozarks. Satellite imagery shows dense cloud cover ahead of the front with clear skies behind it. It`s in this cloudy area that low level flow, wrapping around high pressure over the Southeast, is bringing moisture north from the Gulf of Mexico. Precipitable water values are climbing to around 1.5" ahead of the front. As we head through the afternoon and evening hours, precipitation chances will begin increasing from west to east over southern Indiana and central Kentucky. Even though the area of precipitation isn`t all that wide, the system is moving fairly slowly, so by sunset, many in the Bluegrass and Lake Cumberland regions will likely remain dry. For the areas in the western part of the CWA, model soundings show a decent amount of dry air near the surface with high LCLs over 1 km. MLCAPE could reach a few hundred J/kg, so some thunder could develop. Overall, not expected severe weather. Tonight, sounding profiles quickly become stable with moist profiles saturating the low level dry layer, so the chance of thunder will lessen as the rain moves east across the rest of the CWA. The majority of the CWA will see the majority of their rainfall during the overnight hours. Dubois County, IN could be the exception with most of their rainfall coming prior to 0z Tuesday (8 PM EDT this evening). Lows are expected to fall into the low 60s. The cold front should begin to work into our southern Indiana counties around 10-11z in the morning, and by the afternoon it should be through central Kentucky. Behind the front, winds will flip to the northwest, but they will be light, around 5-10 mph. Skies will quickly clear behind the front. Temperatures will warm into the 70s. Along the eastern side of the CWA, rain may take awhile to come to an end. This will help keep temperatures a little cooler in the low 70s while along and west of Interstate 65, temperatures will likely reach the mid and upper 70s. For most, rainfall totals are expected to range from around half of an inch to around 1.5 inches. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Issued at 333 PM EDT Mon Apr 29 2024 Midweek will feature dry and warm conditions as ridging builds in over the Ohio Valley. Southerly winds will increase WAA over the area pushing afternoon temperatures into the 80s Wednesday with warmest day Thursday and highs in the mid/upper 80s. As the upper ridge continues to become more amplified over the eastern third of the US, an upper trough will become more negatively tilted late Thu into Fri as a sfc slow deepens over the Upper Midwest into western Ontario, Canada. This will push a weak cold front into the Ohio Valley increasing the shower/thunderstorm threat for the end of the week. While the 00z CIPS has a shaded 10 percent probability of severe weather across the eastern half of KY on Fri, the Machine Learning outlook from the same time keeps the better chance of severe off to the southwest over the Lower Mississippi Valley. Models continue to show a couple hundreds J/Kg of SCAPE with a little shear. While not impressed with the threat of severe, still wouldn`t rule out the possibility of some thunderstorms during the day Friday. Timing of the boundary could play a role, as the 12z GFS is a bit faster moving the boundary through during the morning while the ECMWF is slower bringing the boundary and activity through towards the afternoon. Weak area of sfc high pressure will push in over the Great Lakes late Friday into early Saturday ahead of a second cold front that will work in from the northwest out Central Plains on Sunday. Return flow out of the south will advect low-level moistures from the south with increased instability for Saturday. NBM has increased PoPs Saturday from around 30 to now closer to 40/50. Given the latest 12z of the GFS and ECMWF, personally feel this is too high. There continues to be in inconsistency run to run in the models which leads to lower confidence on current rain chances for the start of the weekend. Pattern looks to remain active from the second half of the week into early next week. Ridging looks to build in over the eastern two- thirds of the CONUS for the start of the week. Low 80s and increased dew points into the low 60s will keep instability around each afternoon/evening. Think 30 to 40 PoP seems reasonable at this time. && .AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 808 PM EDT Mon Apr 29 2024 Ahead of an approaching cold front, showers with some very isolated thunder is beginning to enter the region from the west, and as the sun sets, chances of thunder will continue to decrease. An isolated rumble of thunder or two will remain through the night, but expecting mostly rain at area TAF sites. Ceilings are expected to drop into MVFR levels as rainfall becomes more widespread later tonight. A few places could see IFR ceilings for a short time, but the best chances for IFR ceilings currently look to be towards the west, over southwest Indiana and western Kentucky, starting around 10z. This could impact HNB, but believe BWG will remain far enough east to not be impacted. This is as the front begins to work through the area from the northwest. Skies behind the front will begin clearing as winds veer towards the northwest and north. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...KDW SHORT TERM...KDW LONG TERM...BTN AVIATION...KDW