(Des Moines) Chad Hahn, Meteorologist with the National Weather Service in Des Moines, says the EF4 tornado traveled from one end of town to the other in 60 seconds, leaving a path of massive destruction in Greenfield on May 21.
On Thursday, the National Weather Service upgraded the tornado from an EF3 to an EF4, carrying 185-mile-per-hour wind speeds. Hahn says the width of the massive twister spanned just 1000 yards.
Hahn says this was the first time he had to assess tornado damage on foot.
The Tornado claimed four lives, and injured 35 others.
