EF1 tornado in Mercer County, Kentucky

The National Weather Service in Louisville conducted a storm damage survey in Mercer County for storms that rolled through during the mid-morning hours on January 12th. The survey found sporadic topping and twisting of trees on 165 Hunter Drive as well as 1111 Oakland Lane, where the tornado initially touched down. The damage was consistent with 70-75 mph wind gusts with a width of 80 yards.

The tornado continued downstream to a farm on the south side of Cornishville Road. It had sporadic tree damage including snapping, topping, and twisting of some softwood trees. It then destroyed an older barn, throwing roofing from the barn up to 200 yards downwind. The winds were between 75 to 85 mph during this portion of the tornado path.

The tornado increased in intensity at 1966 Cornishville Road, causing significant roof and gutter damage to two homes. Several trees were snapped and twisted. A large, older barn sustained significant roof and side panel damage. The debris from the roofs of two houses along with the barn was thrown towards the north, east, and southeasterly directions. A few pieces from the roof of the house were impaled in the ground. Winds in this area were between 95 to 100 mph with a width of 75 yards.

The tornado became more intermittent as it moved off to the east northeast. There was sporadic minor tree damage and two flipped sets of bleachers on the west side of Kenneth D. King Middle School near the tennis courts. Winds that struck the bleachers were around 75 mph. The tornado then lifted before hitting the school.

During the morning hours of January 12th, an area of low pressure moved through the Ohio Valley downstream of an upper trough across the mid-Mississippi Valley. The initial wave of storms along a warm front moved across north central Kentucky and southern Indiana during the pre-dawn hours, bringing generally sub-severe hail with isolated quarter-sized hail reports. Storms along this boundary were not surface based, but were able to utilize 500-1000 J/kg MUCAPE via steep mid-level lapse rates to produce convection which was of sufficient depth and strength to produce hailstones. Wind shear was more than sufficient for sustaining convection throughout the event, with anywhere from 50-60 kt effective bulk shear across central Kentucky. The second wave of severe convection formed ahead of the surface cold front, moving from west to east across the region during the early and mid-morning hours as a broken quasi-linear convective system (QLCS). Modest destabilization occurred ahead of this second line of storms; however, the antecedent near-surface inversion was able to erode, contributing to the development of 200-500 J/kg of SBCAPE. As a result, severe impacts transitioned from predominantly elevated ones to surface-based threats. While scattered straight-line wind damage was initially the dominant severe impact, convection encountered a local maximum in 0-1 km storm-relative helicity as it crossed Interstate 65, with greater than 300 m2/s2 0-1 km SRH analyzed on SPC hourly mesoscale analysis. In addition, the segment of the QLCS which passed through the Bluegrass region had an orientation which was more perpendicular to the 0-3 km bulk shear vector, indicating a greater potential for embedded tornadoes. Accordingly, appendages and breaks within the QLCS produced several brief tornadoes across the area, with tornadoes being reported in Henry, Mercer, Boyle, and Madison Counties. The line continued to push into eastern Kentucky during the late morning hours, with the severe threat ending shortly thereafter.