Since the 1950s, extreme precipitation events have become more frequent across the globe. In the United States the areas that have seen the biggest increase is the Midwest and the Northeast.
“The greater increases have been seen in the summer and fall,” said Scott Whittier a meteorologist at National Weather Service Burlington. “But we have even seen a few now during the height of the spring snowmelt season which has exasperated current snowmelt flooding.”
As out planet continues to warm, these events may become even more frequent because warmer air can hold more water vapor. For each degree of warming, the air’s capacity for water vapor goes up by about 7 percent. An atmosphere with more water vapor can lead to intense precipitation events.
“We see our dewpoints getting into the 70s, it’s becoming more frequent now” says Whittier. “When dewpoints are in the 70s generally the atmosphere is very ripe. Those types of air masses are becoming more frequent and it just requires a special trigger, a front, something that will bring those rainfall events into us.”
This can lead to threats across the region, especially flooding. Ten years ago, Tropical Storm Irene devastated southern portions of Vermont and New York with up to 11 inches of rain in some locations.
“That is the type of flash flooding we can expect more of with these extreme precipitation events” said Whittier.
There are ways however for our communities to become more resilient as extreme precipitation events become more likely. Whittier thinks more towns need to “look at those buildings or houses on floodplains that flood frequently, maybe looking into buying out some of these properties. Because its not a matter of if but its going to be a matter of when.”