Maine has been getting more rain and snow each year, in part because of more intense storms brought on by climate change, yet the state is still experiencing droughts, according to weather forecasters and climatologists.
According to the National Weather Service, Maine has abnormally dry or moderate drought conditions in coastal, eastern and far northern parts of the state — so far not as bad as the drought that affected Maine last summer and fall. But precipitation from the “worst” storms in the Northeast has increased by 27 percent since 1901, according to a report by federal scientists published Monday by the New York Times.
On the surface, those facts seem to conflict with one another: How can Maine be getting more precipitation and yet also have crops that suffer from a lack of water?
The answer lies in how and where the rain falls in Maine, according to Sean Birkel, a research professor at University of Maine and the state’s official climatologist.
Drought conditions can spring up relatively quickly, in a matter of weeks, whereas the trend of increasing precipitation is borne out by decades of weather data, he said. And the rain and snow that falls in Maine is not spread evenly throughout the state, which can result in significant differences within Maine from one season to the next.
“It plays a significant role,” Birkel said Wednesday of where rain falls in the state. “Northernmost Maine has a different climate from southernmost Maine.”
Maine, like the rest of the Northeast, is getting greater amounts of torrential rain and snow from storms, which has contributed to the increase in annual statewide precipitation, Birkel said. Since 1895, the average amount of rainfall that Maine gets each year has increased by 6 inches to nearly 46 inches.
And since 2010, the number of storms that dump heavy amounts of rain and snow in Maine has been increasing, Birkel said. Instead of seeing one or two storms each year that dump 2 or more inches of rain within a 24-hour period — or the equivalent of that in snow — many sites around the state have gotten three or four such storms annually since 2010. The greater frequency of heavier storms has been more distinct in the lower half of the state — roughly south of Lincoln — than in more remote sections of northern Maine.
So where do the droughts come in? As Maine gets more intense rainstorms, the saturated ground may cause more of the rain to be funneled into rivers and flow out to sea, rather than seeping more slowly into the water table underground, Birkel said. And as more rain falls in shorter time periods, it leaves longer gaps between rain events during which time topsoil can dry out and well levels can decrease.
The intensifying rain storms “do not preclude seasonal drought” or even droughts that extend from one year into the next, Birkel said.
“More of that [precipitation] is being delivered in bursts,” he said.
Precipitation levels can vary greatly within Maine, he added. In the winter of 2015, eastern coastal Washington County got nearly 200 inches of snow, but the mountains in western Maine got relatively little. In 2009, coastal Maine received close to 6 feet of rain for the year while northern Aroostook County got roughly half that amount.