The trail of twisted metal and torn roofs left behind by massive twisters is growing longer and wider, a sign that tornadoes may be growing stronger.
Unusual November tornadoes left a trail of destruction across 12 Midwest states on Sunday, killing at least six people.
The tornado outbreak was caused by a clash of cold, dry air from the north and warm, moist air from the Gulf of Mexico.
Local residents count the cost after a deadly tornado flattened huge areas of Oklahoma City's suburbs on May 20, 2013.
The frequency of tornadoes this year indicates variability in the northward migration of the summer jet stream.
The "Superstorm" that brought tornadoes and damaging winds to the Midwest broke all the records for its intensity.
Forecasters are getting better at providing more advance warning for impending tornado strikes.
Discovery Storm Chasers in action yesterday worked with emergency responders to help track the directions of the tornadoes as they swept across the the Midwestern United States.
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