Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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248 FXUS63 KLMK 270547 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 147 AM EDT Mon May 27 2024 .KEY MESSAGES... * Severe weather and flash flood threat coming to an end overnight. * Breezy Monday with isolated to scattered showers possible. * Dry and cool for most of the upcoming week. && .UPDATE... Issued at 147 AM EDT Mon May 27 2024 Leading line convection has pushed into eastern Kentucky, allowing us to clear the remainder of our County Warning Area from WW 324 and WW 327. Still have trailing stratiform rain that will persist for a few more hrs, but the SVR threat has diminished. Flash flood threat also diminishing, but there are areas in south-central Kentucky where high water will continue to be a problem. Those are covered with Flood Advisories. Given that it`s still raining, expect it would be closer to the main forecast issuance at 3 AM when we drop the Flood Watch. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 252 PM EDT Sun May 26 2024 Round 1 will be ending over the next hour or two across the southern CWA. Pretty tight boundary just south of the KY/TN state line that is the difference between stable and unstable airmasses. Will be continuing to keep an eye on that boundary to make sure that surface- based potential doesn`t creep back up into our southern tier of counties before it exits the Lake Cumberland region. Still, with the near-surface stable layer, expect that 40 to 50 mph winds could still make it to the surface. Still expecting a lull in action between 4 and 7 PM EDT before activity likely ramps up again. Seeing clearing on satellite imagery starting to move into SW Indiana and western KY. May get a few hours of heating in place before the next wave development. Although we aren`t totally sure how well we`ll re-destabilize we are seeing obs jump back up into the mid 70s/mid 60s type of obs over southern IL after an hour or two of heating. That is concerning, and given that the HRRR has not back off the secondary development, do think we can still have high confidence in those storms developing. Speaking of development, it does look like there will be plenty of trigger. Expect the low level jet to ramp up between 40 and 50 knots by 00 to 03z, beneath good exit region mid to upper level jetting. This should set the stage for potential of initial cells being able to rotate (supercells). Do expect that there may continue to be a near-surface stable layer, as indicated by hi-res models consistently, which could limit our tornado threat/keep them a little elevated. Initial cells would probably have a large hail threat give good mid level lapse rates and MUCAPE values. It appears that storms will congeal quickly into a line and then begin to bow out along the I-64 corridor from 8PM to 10 PM. From there, it should work steadily across KY and exit our SE between 2 and 3 AM EDT. Once the expected cold pool gets going, then would fully expect that the stable layer could be overcome and that those pockets of severe winds could again be mixed down. Still our expected main threat going through the late evening and into the overnight. Will be looking to clear the Watches from Wave 1 shortly. && .LONG TERM /TONIGHT THROUGH SUNDAY/... Issued at 252 PM EDT Sun May 26 2024 Monday through Tuesday Night... Deep low pressure is forecast to reach Lower MI by 12Z Monday, with a trailing cold front advancing through central IN and western KY. A trailing upper level shortwave trough will swing across the Ohio Valley Monday morning as the cold front moves through the region. This could touch off a few weak showers and storms early in the day, though most will see a dry start to the day in the wake of severe storms late Sunday. There is a slightly greater chance (30%) for showers and storms in the Bluegrass/Lake Cumberland regions in the afternoon. Slightly richer moisture and a bit more time for the airmass to destabilize prior to fropa results in the slightly higher rain chances. However, precip will be sparse overall. Expect a mostly cloudy start to the day, with lower clouds thinning during the second half of the day. It will be breezy with gusts of 20-30 mph. Highs will range from the mid 70s to around 80 F. Notable upper level troughing lingers over the Great Lakes and Upper Midwest through Tuesday night, keeping deeper moisture bottled up to our north. An amplifying upper level ridge builds from the Rockies to the Plains as sfc high pressure strengthens over the northern and central Plains. Largely dry weather is expected with lows in the 50s and afternoon highs in the mid 70s to near 80 F. Wednesday through Saturday... Ridging builds east across the MS and OH Valleys through late week, resulting in a stretch of pleasant weather. Highs will be in the 70s Wednesday and Thursday with comfortable humidity levels. Morning lows will generally be in the 50s, though some spots will see readings in the 40s Thursday and Friday mornings. Temperatures will warm back to around 80 degrees Friday afternoon. A highly meridional flow pattern will be in place heading into next weekend. Ridging slowly drifts to the east as a Plains low pressure system moves toward the region. Rain returns to the forecast for late Saturday or Sunday, though timing remains uncertain. && .AVIATION /06Z TAFS THROUGH 12Z TUESDAY/... Issued at 117 AM EDT Mon May 27 2024 Convective line moving through LEX at the moment, but may well taper off to stratiform before the valid time of the TAF. Expect a post- convective environment at all the terminals roughly 06-08Z, with light rain out of a mainly mid-level ceiling and chaotic, often E-NE winds. Will handle the odd rumble of thunder with VCTS. Sfc cold front arrives near daybreak with a shift to westerly winds and a few hrs of MVFR stratus. Will keep SDF just above 2000 feet but take LEX and BWG a bit lower. As mixing deepens through the day, look for cigs to lift to VFR and winds to pick up to near 15 kt with 20-25 kt gusts. Loss of heating will allow the boundary layer to decouple after sunset. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...Flood Watch until 8 AM EDT /7 AM CDT/ this morning for KYZ023>043-045>049-053>057-061>067-070>078-081-082. IN...Flood Watch until 8 AM EDT /7 AM CDT/ this morning for INZ076>079-083-084-089>092. && $$ UPDATE...RAS SHORT TERM...BJS LONG TERM...EBW AVIATION...RAS