1976 Lemont–Argonne tornado

On the evening of June 13, 1976, a violent F4 tornado affected areas of Lemont, Argonne National Laboratory, and modern-day Downers Grove in Illinois. The tornado was surrounded by two satellite tornadoes throughout its lifecycle. The tornado occurred on the same day as the violent 1976 Jordan tornado.

Meteorological synopsis

From June 12, 1976 to June 14, an active pattern had been in force over much of the Midwest between which had included severe thunderstorms across Illinois. In the evening hours, a violent thunderstorm known as a cooling lake breeze acted as a small cold front.

Tornado summary

The tornado first touched down north of downtown Lemont. It became a massive wedge tornado as it moved across Lemont. As it moved southeast, it crossed McCarthy road and impacted Lemont High School at F1 intensity. After it hit the school, the tornado started rapidly intensifying and strengthening, producing F4 damage to many homes. The tornado would claim 2 lives. The tornado started weakening as it looped around Lemont but a satellite tornado formed across it. The first satellite tornado quickly dissipated, receiving a FU tornado rating, though a second satellite tornado formed soon after. The main Lemont tornado continued to undergo a looping process as it remained nearly stationary. The second satellite tornado damaged some houses before quickly dissipating as well — this satellite would be rated an F1. Shortly after, the Lemont tornado would finish its looping process leaving the area "left looking like a war-torn battlefield".

Hit on Hasting

As the tornado entered Hastings, Illinois, it started following an erratic path, though fortunately for the people of the town, the tornado was weakened at this point. No fatalities would be caused.

Near hit on Argonne National Laboratory and dissipation

The tornado turned towards a northerly bearing as it crossed the Des Plaines River. This turn would set it on a path towards Argonne National Laboratory. However, prior to hitting the lab, the tornado would curve away, missing the lab. Afterwards, the tornado would move across rural areas before quickly dissipating.

Legacy

Other tornadoes

Besides the 1976 Lemont tornado and its satellites, as well as the Jordan tornado and its satellites, no other violent tornado appeared.

Rating dispute

In 2026, NWS Chicago revisited this tornado and gave it a rating of EF4 with winds of 170 miles per hour. According to this new survey the tornado only reached a width of 800 yards wide.

See also

• 2007 Greensburg tornado, another violent tornado noted for satellite tornado activity
• 1976 Jordan tornado, the other tornado that formed on the same day
• Tornadoes of 1976

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