EF1 tornado in Knox County, Indiana

Tornado crossed a county line 10 times in its 26.7-mile track from Illinois to Indiana, see below for lat/long/location/time details for each border crossing.

The tornado first entered the extreme southwestern corner of Knox County at 940 PM EST and proceeded to cause damage consistent with EF0/EF1 intensity: snapping two hardwood trees that fell onto power lines on South 1300 West at 13.4 miles west, breaking large hardwood tree branches on South County Road 1300 West at 18.3 miles south, and leaning two utility poles on South 1200 West at 19.9 miles south.

The tornado's center track then crossed the Knox-Gibson county line 4 times over a 1.4-mile segment roughly midway between Mt. Carmel, IL and Hazleton, IN before re-entering Knox County to cause damage consistent with EF0 intensity during 944-949 PM EST: breaking small hardwood tree limbs on South County Road 775 West at 18.6 miles south; and then along the 17.8 South parallel, blowing over 5 irrigation sections at 8.7 miles west, before blowing over two more irrigation sections and blowing in a barn door and tree damage at 8.1 miles west; and then breaking large hardwood tree branches along South County Road 775 West at both 17.0 miles south and 16.55 miles south.

The tornado track then entered the appendage of Gibson County west of Hazleton, IN for 0.5 miles before again re-entering Knox County to cause damage consistent with EF1 intensity at 952 PM EST: leaning utility poles and snapping several tree branches on West County Road 1750 South just west of Old US Route 41.

The tornado track then entered Gibson County for the final time while transecting the appendage north of Hazleton, IN for 1.0 miles before re-entering Knox County for the final time to cause damage consistent with EF0/EF1 intensity at 954 PM EST in the town of Decker, IN: uprooting large hardwood trees along Broadway Street near 3rd Street, with large hardwood branches snapped across southern and eastern portions of Decker.

The tornado continued to the northeast, next causing damage consistent with EF0/EF1 intensity during 955-959 PM EST: snapping branches of various sizes from both softwood and hardwood trees along Indiana Route 241 and East County Road 1250 South to the west of Iona, IN; as well as destroying an old barn on East 1250 South just east of South Decker Road by lifting the roof which allowed the walls to collapse.

The tornado's final observed damage was consistent with EF1 intensity during 1000-1003 PM EST : snapping several softwood trees on South Hart Road just northwest of Upper River Deshee, and fully destroying a barn on Southeast County Road 200 East east of Upper River Deshee, scattering debris several hundred feet to the northeast.

Further data regarding every county/state border crossing.

ILLINOIS: traveled 8.33 miles as EF0-EF2 before entering Gibson County Indiana.

INDIANA: traveled 18.36 miles as EF0-EF1: Gibson Co. (3.51 mi), Knox Co. (14.85 mi).

A, 38.410/-87.745, Mt. Carmel 1.1 ESE, 2139EST, Illinois to Indiana;

B, 38.417/-87.732, Mt. Carmel 1.8 E, 2140EST, Gibson to Knox;

C, 38.446/-87.674, Mt. Carmel 5.3 ENE, 2143EST, Knox to Gibson;

D, 38.448/-87.669, Mt. Carmel 5.6 ENE, 2143EST, Gibson to Knox;

E, 38.450/-87.664, Mt. Carmel 5.9 ENE, 2143EST, Knox to Gibson;

F, 38.455/-87.651, Mt. Carmel 6.7 ENE, 2144EST, Gibson to Knox;

G, 38.490/-87.586, Hazleton 2.3 W, 2150EST, Knox to Gibson;

H, 38.494/-87.577, Hazleton 1.9 W, 2150EST, Gibson to Knox;

I, 38.507/-87.546, Hazleton 1.2 N, 2152EST, Knox to Gibson;

J, 38.515/-87.530, Decker 0.4 SSW, 2153EST, Gibson to Knox;

K, 38.609/-87.400, Monroe City 2.5 WSW, 2203EST, End of track in Knox Co, IN.

Ample instability and low-level vertical wind shear across central Indiana combined with a warm frontal boundary approaching from the south to produce several rotating, supercell thunderstorms. These storms produced large hail within a two hour late day period over several of the region's southwestern to south-central counties

Soon after, a rotating cluster of thunderstorms crossed southern central Indiana during the evening and early morning hours. This relative small, yet intense, complex of storms produced a long-track EF-1 tornado from Illinois into Gibson and Knox Counties in Indiana, as well as isolated, locally intense, damaging winds that were mainly in southeastern central Indiana.