Twisters have historically formed in large numbers through a Midwestern corridor known as Tornado Alley. It stretches from central Texas to northern Iowa and from central Kansas and Nebraska to western Ohio, according to the National Climatic Data Center. Intense tornado activity that now stretches beyond the "alley" has "forced many insurance companies to rethink the way they assess natural hazard risk," Howard Botts, a vice president of CoreLogic, wrote in a report in March.
Damage from a tornado on June 8, in Ramah, Colo. The twister was part of a powerful storm system that rolled through parts of Colorado and Wyoming, packing heavy rains, high winds and hail. The storms followed a round of nasty late spring weather that pummeled the region.
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