How weather detectives use devastation to decode tornadoes

BESSEMER, Ala. -- Seventy six tornadoes tore through the South and Midwest this week. As the cleanup continues, tornado experts have another job to do.

CBS News caught up a National Weather Service Storm Survey Team in Bessemer, Ala. Teams such as these go to damaged areas as soon as they can -- just as detectives rush to a crime scene. The damage is the fingerprint the tornado leaves behind.

Meteorologist Jim Stefkovich told CBS News they wanted to look at debris before anyone cleans it up. He said, "We can look at the damage that is back to the southwest, it was coming this way and then got, picked up the roof and then threw it in this direction. So, that lets us know obviously the path of which way it was going."

Meteorologist Jim Stefkovich CBS
Measurements, observations and witness interviews were compared with radar information recorded at the time of the tornado.

Photos and data from teams across the region were sent to an office in Birmingham where it was pieced together to show the path of the tornado.

Stefkovich, asked why anyone should care about the report, said, "The ultimate goal is...we want people weather ready. We find out where the tornado began, where it ended, the width, the maximum intensity. It can be used for research, used for insurance, it can be used in multiple ways."

Such as improving building designs and better forecasting.

The survey teams found the Bessemer tornado had winds up to 120 miles per hour. But a full analysis of the tornado outbreak is expected to take weeks.