Thunderstorm Wind in Butler County, Kentucky

Trees were blown down near the intersection of U.S. Route 231 and Little Muddy Church Road.

Another active period of weather set up across central Kentucky and southern Indiana July 17th and 18th, 2023 as multiple waves of showers and thunderstorms moved across the region, bringing damaging straight-line winds, severe hail, and one tornado to the region. The synoptic pattern was fairly consistent (albeit active) during this period, with large-scale mid- and upper-level troughing extending from Hudson Bay down into the Ohio Valley. In the low-levels, a quasi-stationary front extended from the mid-Mississippi Valley across central Indiana and into northern Ohio, with a seasonably warm and unstable air mass present across the Ohio Valley, which was primarily located south of the low-level frontal boundary. The first wave of strong to severe storms developed during the late afternoon hours in the vicinity of the frontal boundary across central Indiana. As these cells morphed into a quasi-linear convective system during the evening hours, the combined cold pool development forced the storms southward into southern Indiana and central Kentucky. Ahead of the line of storms, mixed-layer CAPE on the order of 1500-2500 J/kg and effective bulk shear of 30-40 kt provided a favorable parameter space to sustain strong-to-severe convection. This line of storms ultimately produced sporadic wind damage and near-severe hail across southern Indiana and north central Kentucky, with convection lingering into south central Kentucky overnight before gradually dissipating in the early morning hours on July 18th.

While sporadic convection continued through the morning hours on July 18th, the next main wave of strong and occasionally severe thunderstorms arrived during the early afternoon hours. With unseasonably fast flow continuing aloft, wind shear remained sufficient for multicell clusters and a few supercells to develop across central Kentucky. Instability remained moderate to high, with low-to-mid 70s dewpoints and temperatures in the 80s allowing for the development of 2000-3000 J/kg MLCAPE. This initial wave of cells produced scattered wind damage and hail mainly across the Kentucky Bluegrass. Additionally, a decaying mesoscale convective system coming in from western Kentucky also produced scattered wind damage across southern and central Kentucky. One brief spin-up tornado developed within this line over Marion County, producing EF0 damage. Convection dissipated once the line of storms cleared the area around sunset. As a result of multiple waves of heavy rainfall moving over the same areas, scattered occurrences of flooding were observed across the area, with the most concentrated area of flooding occurring over eastern Jefferson County and Shelby County, Kentucky.