Chicago ? A massive storm with wind gusts up to 81 mph howled across the nation’s midsection Tuesday, snapping trees and power lines, ripping off roofs, delaying flights and soaking commuters hunched under crumpled umbrellas.

Damaged tree limbs can be seen near a barn that was lifted off its foundation by a tornado Tuesday in Mount Pleasant, Wis. Wisconsin was one of 11 states in the Midwest that was under a high wind warning Tuesday when a strong storm system moved through.

Spanning from the Dakotas to the eastern Great Lakes, the unusual system mesmerized meteorologists because of its size and because it had barometric pressure similar to a Category 3 hurricane, but with much less destructive power.

Scientists said the storm had the force of a blizzard minus the snow.

“If it were colder, we’d have a blizzard with this system,” said David Imy, operations chief at the National Oceanic and Atmospheric Administration’s Storm Prediction Center in Norman, Okla.

But temperatures were in the 50s and 60s, instead of the 20s.

The agency said the system’s pressure reading Tuesday was among the lowest ever in a nontropical storm in the mainland U.S. Spokeswoman Susan Buchanan said the storm was within the top five strongest storms in terms of low pressure, but may not have been the strongest on record.

Earlier, the agency said the storm’s pressure was worse than that produced the Blizzard of 1978, the March 1993 “Storm of the Century” or the November 1975 storm that sank the Edmund Fitzgerald freighter, memorialized in a song by Gordon Lightfoot.

The storm blew in from the Pacific Northwest on the strength of a jet stream that is about one-third stronger than normal for this time of year, Imy said. As the system moved into the nation’s heartland, it drew in warm air needed to fuel thunderstorms. Then the winds intensified and tornadoes formed.

Add to that the fact the storm was moving fast, 50 to 60 mph, and the winds became even stronger, Imy said.

By Tuesday morning, sustained winds were about 35 to 40 mph and gusting much higher.

A gust of 81 mph was recorded in Butlerville, Ohio, and 80 mph in Greenfield, Ind., according to NOAA.

At one point, more than 145,000 homes and businesses were without power in Wisconsin, Indiana, Illinois, Ohio and the St. Louis area.

The storms were headed toward the East Coast by late afternoon, and winds were expected to subside in the evening. But forecasters said the winds could pick up again today.

A tornado touched down in Racine County, Wis., where two people were injured when a section of roof was torn off a tractor factory, and in Van Wert County, Ohio, near the Indiana border, where a barn was flattened and flipped over a tractor-trailer and camper.

A tornado also touched down in Peotone, Ill., where three people were injured when a home’s roof came off, and twisters were suspected in several other states.