Tornado season off to a slow start
Minnesota has gone without any tornadoes this year as cool weather has made twisters scarce throughout the United States.
But memories of last year -- when Minnesota had a record 74 tornadoes and Siren, Wis., was ravaged by a large one that killed three people -- were still fresh as Severe Weather Awareness Week began Monday.
The United States has recorded only about 60 tornadoes so far this year, compared with a normal 200. No deaths have been reported, making this the latest the country has gone without a tornado death since record keeping began in 1950.
April, May and June are the main tornado months in Minnesota, but tornadoes have occurred as early as March and as late as October.
By this date four years ago, Minnesota had already recorded 21 tornadoes in a massive outbreak that struck the Comfrey-St. Peter area March 29, 1998, killing two people and damaging every building at Gustavus Adolphus College in St. Peter and nearly every structure in Comfrey.
As tornado forecasting and warning systems improve, fewer people are killed in the storms. The 10 deadliest tornadoes in U.S. history took place before 1954.
The deadliest tornado ever recorded killed about 1,300 people in Bangladesh on April 26, 1989. In the United States, the deadliest recent tornado killed 44 people as it tore a 60-mile path though Oklahoma -- including Oklahoma City -- on May 3, 1999.
"It was very wide, very intense and in an extremely developed area," said Tom Grazulis, a meteorologist who runs the www.tornadoproject.com Web site. "It was raining automobiles. One dealership had 800 cars destroyed, and some just fell from the sky like rain."
Television stations watched the tornado long before it reached Oklahoma City, and there was plenty of warning, said Grazulis, author of the new book "The Tornado: Nature's Ultimate Windstorm."
The Oklahoma tornado also tarnished the popular notion that highway underpasses are safe places to take shelter in a tornado.
"Tornadoes passed over four underpasses in Oklahoma, and there were deaths in three of them," Grazulis said.
The myth that underpasses are safe grew largely because of a highly publicized video made by a television crew in Kansas that survived a weak tornado in 1991.
Many people think opening windows in a house will help protect the house in a tornado by somehow equalizing the pressure. The powerful winds of a tornado would flatten your house long before the pressure difference became important, Grazulis said.
It's often said the southwest corner of the basement is the best place to take shelter, but Grazulis said it's better to take cover under a stairwell or heavy workbench.
The Tornado Project: http://www.tornadoproject.com
National Weather Service in Chanhassen http://www.crh.noaa.gov/mpx