EF1 tornado in Henry County, Illinois

A high end EF1 tornado formed about 4 miles west of Annawan, IL at 556 PM CST. The tornado initially caused damage to tree limbs before intensifying as it approached Highway 6. At this point the tornado hit two homesteads causing damaging to siding and shingles at each homestead. One of the homesteads saw a shed

destroyed. The tornado reached peak intensity just north of Highway 6, where a well constructed shop was destroyed by the tornado. This damage was rated at 110 MPH winds. The tornado then started to occlude and move more to the left as it crossed I-80. A semi was flipped around I-80 mile marker 31. A couple of branches were broken on the other side of I-80. Around 604 PM CST, the tornado dissipated just north of I-80. The overall path was 2.8 miles and the max width of the tornado was around 425 yards.

A strong cold front coupled with an anomalously warm air mass (highs in the 70s that broke records for the day, month, and season) and sufficient moisture set the stage for the development of severe thunderstorms across portions of northwest Illinois between 4 PM and 7 PM on Tuesday, February 27.

Storms quickly became severe after they developed across northwest Illinois during the late afternoon. As they tracked eastward, they produced hail up the size of golf balls, most notably around the Geneseo, IL and Atkinson, IL vicinities, and one confirmed EF1 tornado in the vicinity of Annawan, IL around 6 PM. A Tornado Warning was issued near 5:30 PM for this storm (NWS headline map at that time).

Storms progressed east across northern Illinois during the evening with several more tornadoes in the NWS Chicago County Warning Area. The storms were soon followed by strong non-thunderstorm winds gusting 40-50 MPH with the cold front passage.