The May 1975 Omaha TornadoIt lasted less than half an hour, but by the time it was done, it had become one of the costliest tornados in U.S. history. We remember the day, the event and the Story by Mike Whye |
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WHEN THE SUN ROSE at 6:15 on May 6, 1975, George Matuella had been watching the radarscope at the National Weather Service station north of I-680 on Omaha’s northwest side for more than two hours. He noticed when he had come to work how the morning air was heavy with moisture warmed days earlier over the Gulf of Mexico. As the yellow arm of the radarscope swept around, Matuella could tell from the brightness and configuration of the echoes what clouds near and far looked like plus how fast they were moving and how high they rose in the sky. When the station’s meteorologist-in-chief, Jim Zoller, arrived, he too noticed the heavy outside air. “We’re in for a good one,” he told Matuella.
Across the central Great Plains that day, a mass of cool, dry air was pushing south against the warm humid air. As with a glass of ice water set in a warm room, moisture began to form, creating clouds that were carried upward by the rising warm air, creating a host of cauliflower-shaped boils rising tens of thousands of feet above the ground.
In each storm system, raindrops in endless numbers rubbed each other and, although seemingly impossible for something made of water to do, they created static electricity, sparking bolts and sheets of lightning, followed by rumbling thunder. Warm updrafts rose within the clouds at up to 100 mph and were twisted to the left by heavy winds entering the storm cell with greater velocity the higher they came into the storm. Soon, the entire storm was rotating counterclockwise. No longer ordinary thunderstorms, the storms were supercells containing rotating updrafts – mesocyclones, the mothers of tornadoes.
Matuella, 37, watched the storms brew on his radarscope. “By 11 a.m., I knew things were going to get bad,” he said.
All along the front where the masses of air collided, mesocyclones were turning above eastern Nebraska, southeastern South Dakota and western Iowa. A few minutes after noon, the first tornado of the day touched down near Kimball, S.D. At 12:37 p.m., the Severe Storms Forecast Center in Kansas City, Mo., issued a tornado watch for eastern Nebraska, starting at 2 p.m. As if on schedule, the first tornado to hit Nebraska landed north of Pierce at 2:05 p.m.; on the Fujita scale then in use, it was a powerful F4, which meant its winds were between 208 and 260 mph.
Ten minutes later, the core of a slower F3 descended east of Pierce to begin a 45-mile-long run north toward the Missouri River, tearing up half of Magnet, population 88, along the way. In the next half hour, another F3 ripped up parts of Stanton and Wayne counties while a fourth, with winds between 40 and 72 mph, hit Knox County.