By Lani Duke
After analyzing more than a century’s precipitation records, Dartmouth College researchers concluded northern New England weather patterns have indeed changed. Intense rain events of two or more inches inside of 24 hours are 53 percent more likely than they were in the 1990s, researcher Jonathan Winter told the Valley News, June 19.
Winters and colleagues Huanping Huang and Erich Osterberg found that 1996 was a significant demarcation point. Before that year, there was little precipitation increase at 116 stations in the Northeast, but their analysis revealed a 53 percent increase in “extreme precipitation” from 1996 to 2014, primarily in spring and fall. They published the study in the American Meteorological Society Journal of Hydrometeorology.
Flooding is more likely at times when the soil is already saturated, Winter said. June 19, 2017 proved his projection, with 4.3 inches recorded at a Windham County weather station and 1.51 in Woodstock, resulting in downed trees, flooded roads, and a Route 30 mudslide.
These changing weather patterns must figure into plans for property developers working in flood zones and engineers who design and build stormwater systems. They need to plan for larger diameter pipes, and add in more gravel and grassy areas to slow down traveling precipitation.