A study from the University of Iowa has found that heavy rains in the upper Midwest have become more frequent in the last 60 years. This is in spite of the recent drought conditions in the region.
Researchers studied the frequency of heavy rainfall using data from 447 rain gauge stations throughout the central and southern U.S. The data went back to the mid-20th century. They found that a rise in surface temperatures has led to more water being absorbed by the atmosphere. The extra atmospheric moisture, they say, has increased the likelihood of heavier rains.
Data from thirteen U.S. states was included in the study. It was supported by NASA and the Willis Research Network, a philanthropic effort sponsored by the London-based Willis Group.