Thunderstorm Wind in Monroe County, Kentucky

Several trees were blown over by strong thunderstorm winds in western Monroe County.

An upper level low which had meandered over the mid-Mississippi Valley for several days began to eject northeastward, opening up into a trough on June 18th. At the surface, low pressure developed over Missouri and Illinois as a cold front sagged slowly to the south and east. During the late morning and early afternoon hours, showers and thunderstorms developed along a remnant outflow boundary and pushed eastward across Illinois. Ahead of the storms, a strongly unstable environment was present across southern Indiana and central Kentucky, as temperatures warmed into the mid-to-upper 80s and dew point temperatures were in the low-to-mid 70s. This resulted in around 3000 J/kg MLCAPE and 4000 J/kg SBCAPE over the area during the afternoon hours, providing plenty of energy for storms to work with. The strongest mid-level flow and deep-layer shear during this event was located over central Indiana; however, there was still 25-35 knots of effective bulk shear which helped to keep storms organized into multicell clusters which eventually grew upscale into a broken line. While reasonably steep mid-level lapse rates and the initially discrete nature of convection allowed for a few instances of severe hail in southern Indiana, the main severe hazard with this event were damaging straight-line winds, with scattered wind damage and measured severe wind gusts observed across southern Indiana and central Kentucky. A second wave of strong to occasionally severe thunderstorms moved through during the late evening hours, though increased stability limited wind damage to much more isolated instances.