"East of the Rockies, more rain is falling, and it’s coming in more intense bursts. In the West, people are waiting longer to see any rain at all."
Excerpt from this story from USA Today:
For our climate change investigation out this week, called Downpour, USA TODAY reporters used 126 years of monthly data from the National Oceanic and Atmospheric Administration to analyze average annual precipitation at 344 climate divisions. They used daily precipitation data from weather stations to measure the change in frequency of extreme rain events across the U.S. from 1951-2020.
We found more than half of the nation's 344 climate divisions had their wettest periods on record since 2018. We calculated the same rolling averages for states.
"East of the Rockies, more rain is falling, and it’s coming in more intense bursts," our report finds. "In the West, people are waiting longer to see any rain at all.
"Taken together, the reporting reveals a stunning shift in the way precipitation falls in America."
Specifically, our reporting finds:
At some point over the past three years, 27 states – all east of the Rocky Mountains – hit their highest 30-year precipitation average since record keeping began in 1895.
A dozen states, including Iowa, Ohio and Rhode Island, saw five of their 10 wettest years in history over the past two decades.
Michigan saw six of its wettest 10 years on record over the past 13 years.
In June, at least 136 daily rainfall records were set during storms across five states along the Mississippi River.
At the opposite extreme, eight states – including five in the West – had at least three record-dry years in the same time period. That’s double what would be expected based on historical patterns.
Michael Mann, a climatologist at Penn State University, told our reporters the greenhouse effect is important to keep Earth from freezing, but excess heat greatly reduces the temperature difference between the warmer tropics and cooler polar regions in the summer.
Mann said that reduction in the temperature difference slows down the jet stream, which makes it weaker and wavier in the summer. That means weather systems moving across the country can slow or stall more often.
"The gentle rains for a number of days are kind of disappearing and are being replaced by downpours," said Chris Davis, USA TODAY's executive editor for investigations. "And that in and of itself has a lot ramifications, everything from flooding, to mudslides out west, to how much fertilizer gets picked up and carried into the Mississippi River and down into the Gulf of Mexico."













