Tornado outbreak of June 8-11, 2020

As a powerful shortwave trough dropped into the northern United States and move east-southeast, the stage was being set for a multi-day tornado outbreak in the upper Midwest. The Storm Prediction Center had every day on its 4-8 outlook marked for severe weather on June 5. June 8 featured high instability and good shear, but a cap that didn't erode until mid afternoon. The SPC had am enhanced risk with a 10% hatched tornado risk in place for much of central and east North Dakota and South Dakota, with a 5% risk extending into northern Nebraska. 24 tornadoes touched down that day, including one EF4. The most prolific day of the outbreak took place on June 9. a strong surface low was located near the North Dakota/Minnesota border, with a cold front draping down through west MN into northern IA. A warm front in central/north MN was also expected to be a focus for tornadic activity later that day. 0-1 km helicity was in the 300-500 m2/s2 and MLCAPE exceeded 4,000 j/kg in some spots. The SPC issued a moderate risk with a 15% hatched tornado risk for much of central and southern MN, which was eventually upgraded to a high risk at the 2000z outlook. A PDS tornado watch was issued and several long-tracked, intense supercella developed spawning 54 tornadoes, including 8 EF4's. After dark, storms congealed into an MCS, and a few QLCS tornadoes occurred. By morning, the MCS had weakened, and rapid destabilization occurred in north Illinois and southern Wisconsin. The surface low had moved southeast a bit, now positioned near Minneapolis. Again, a moderate risk was issued with a 15% hatched tornado risk. 31 tornadoes touched down, including two EF4's, one of which had a path length of about 91 miles. Activity became sloppy and another MCS formed that evening, but it weakened before dawn on June 11. Another moderate risk was issued that day. The surface low was located in extreme southwest Michigan, and the whole warm sector was primed for supercells and tornadoes. 32 tornadoes touched down, including two long-tracked EF4's. Some areas hit in the April 23, 2018 Ohio Tornado Outbreak were hit again in this outbreak. 41 people died in the outbreak, and it left $1.66 billion in damages.

Tornado Statistics