EF0 tornado in Daviess County, Kentucky

An EF-0 tornado touched down 3 miles west-northwest of West Louisville in western Daviess County, traveled 3.11 miles east-southeast, and lifted at West Louisville. A few large barns and outbuildings had portions of their roofs removed with one outbuilding also losing a portion of an exterior wall. A few wooden power poles were damaged or leaning slightly. A carport was lifted and tossed into the top of a nearby tree. Numerous large tree limbs were downed along the damage path, and one tree in very soggy soil was uprooted. The estimated peak wind was 85 mph and the maximum path width was 300 yards.

A major outbreak of severe weather occurred on the 8th for the Quad State region. On the synoptic scale, a longwave trough was centered across the Rockies with deep-layer southwesterly flow from the Southern Plains to the Ohio Valley. A 110 kt upper jet extended from northern KS to IA while a 60 kt mid-level jet was positioned across northern MZ into IA. Surface low pressure near the MZ/KS border lifted to St. Louis around 12am CST on the 9th. A warm frontal boundary stretched across the Quad State, with a cold front extending southward from the surface low.

The environment became unstable by early afternoon, especially in far Western Kentucky, with MLCAPE of 2000-3000 J/kg. Deep-layer shear was on the order of 55-65 kts, though low-level shear was 15 kts, increasing to 20 kts later in the day. SRH was around 100-2000 m2/s2 with higher values north towards Clarksville, TN. STP values were 2-3 due to deep-layer shear and instability. Supercell activity was more prominent during the afternoon in Western Kentucky with lapse rates of 6.5-7 C/km aiding with hail production.

For Southwest Kentucky, a sub-severe line of storms moved through with a cold front during the overnight hours from the 7th-8th. The front reversed and lifted northward during the morning, producing thunderstorm wind damage in the Purchase area, particularly in and around Calvert City. Supercell development occurred during the afternoon hours with widespread hail and thunderstorm wind damage. An EF-U tornado was identified in eastern McCracken County. Several counties were hit multiple times over the course of the afternoon into the evening as lines of storms entered Northwest Kentucky from Southern Illinois. Daviess County experienced widespread significant wind damage in and west of Owensboro between 2030-2100CST, including 3 tornadoes (2 EF-0 and 1 EF-1). A powerful outflow boundary from the Daviess County storms pushed through Livermore producing a mile wide swath of significant wind damage. A final line of thunderstorms pushed through Western Kentucky late evening past midnight, with limited severe weather.

Torrential rainfall produced flooding impacts across Western Kentucky. A northern high rain total swath extended from Union County to southern Daviess/McLean Counties with 3-5 inches of rain. Being the location where the cold front stalled out and reversed, early morning rainfall totals were already elevated from Marshall/Calloway County to Todd County and further south in Tennessee. Heavy rains from afternoon supercells increased flooding issues, including washing out part of a road in Trigg County, while continued heavy rainfall late evening into the overnight hours left numerous roads flooded in Trigg County and in Hopkinsville. Rainfall totals were 5-8 inches in portions of Marshall and Trigg Counties and southernmost portions of Christian and Todd Counties. Both the Bypass and 68/80 gages on the South Fork of the Little River in Hopkinsville reached minor flood, and significant rainfall totals on the Green River resulted in Paradise reaching moderate flood stage a couple days later.