New York - At the Storm Prediction Center in Norman, Oklahoma last week, lead forecaster Corey Mead was already tracking the early stages of a storm system that would devastate Joplin.
Joplin, Mo., slammed by twister, 116 dead
"We don't fully understand how tornadoes form," Mead says. But, as CBS News senior business correspondent Anthony Mason reports, this 17-year veteran of the National Weather Service says forecasting has improved significantly.
"We can actually anticipate the potential for those types of storms several days out," Mead says. "But the exact locations and timing of more significant tornado threats - sometimes we don't know up until just a few hours leading up to the events."
Video: Raw footage of Joplin, Mo., twister
There were 506 tornadoes reported in the U.S. through this date last year. It's already more than double that - 1151 - this year.
"This is just remarkable from a meteorological point of view," says City College of New York's professor Stan Gedzelman. He says superstorms are formed by an instability in the air that usually occurs in the Spring.
"Yesterday's instability - and the instability of the storms that hit Tuscaloosa is just about as large as I have ever seen," he says.
Pictures: Joplin tornado devastation
Joplin, Mo. tornado: How you can help
Gedzelman sees nothing strange in the weather pattern this year. But year-to-date, tornadoes have killed more than 500 people. That's seven times the average, making this the deadliest tornado season in more than half a century.
"The warning system was absolutely as good as it could be," Gedzelman says. In fact, Joplin residents were given a 24-minute warning. Studies have shown that warning of just 6 to 15 minutes reduce the expected fatalities by more than 40 percent.
"It's really remarkable the accuracy of the forecasts," Gedzelman says. "It's just that the level of destruction is beyond belief."
It's rare for tornadoes of this force to form at all. It's rarer still for them to find population centers like Tuscaloosa and now Joplin.