Tornado in Warren County, Indiana

A storm chaser monitored a landspout tornado that maintained connection to the ground for much of its entire 4.76 mile track from far eastern Illinois into Indiana. The landspout started in Vermillion County, IL (in NWS Lincoln's area) at 1815 EST and crossed into Warren County, IN at 1823 EST. Minor EF0 damage was observed 750 feet west of the state line in Illinois, nonetheless the landspout was rated EFU along the entirety of the 2.25-mile (Indiana) portion of its track in Warren County where no damage was observed.

Southwesterly surface winds ahead of an approaching cold front boosted dewpoints in the afternoon as high as 76 degrees at the Terre Haute and Indianapolis airports, and 77 degrees at Shelbyville. Resulting CAPE of 2000-3000 J/kg initiated thunderstorms over east-central Illinois, which tracked eastward into west-central Indiana. This cluster matured into a bow echo that produced a measured 68 mph gust at Crawfordsville before downing trees across the Indianapolis Metro, most notably the Beech Grove area.

The storms were maintained by 20-30 kts of 0-3 km wind shear, with wind damage reported through Rush County where several large trees were downed. Anomalously high precipitable water values around 2.15 inches promoted isolated heavy rainfall of 2.00 to 2.30 inches from south of Crawfordsville to northern portions of the Indianapolis Metro, although antecedent abnormally dry conditions prevented any flooding.

Finally, an early evening landspout tornado crossed from Vermillion County, Illinois into Warren County, Indiana, while producing no damage along the second half (Indiana portion) of its entire 4.76-mile track, resulting in an EFU rating in Indiana.