The Upper Midwest saw a 31 percent increase in "intense" rainfalls -- the statistical 1 percent events -- from 1958 to 2007, over previous decades, according to the National Climatic Data Center. Last Tuesday and Wednesday's Duluth rainfall, measuring from 7 to more than 10 inches across the city, was in some places nearly double what's regarded as Duluth's 1 percent-chance rainfall. That made it "next to impossible to plan for," Shaffer said.

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