Just last week, Hurricane Teddy took aim at eastern Maine but turned eastward and made landfall along Nova Scotia’s eastern shore, retaining wind speeds of nearly 75 mph until just a few hours before it struck the Canadian province.
And, on Wednesday, a strong wind storm that was neither a bomb cyclone nor a nor’easter caused outages across the state, leaving more than 100,000 electricity customers without power.
The frequency of such storms — such as two that struck Maine within two weeks last October, or two that caused power outages just four days apart in April — could be increasing because of the changing climate, as warming oceans are putting more moisture in the atmosphere, according to a scientist at University of Maine.
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But it’s not an easy question to answer, in part because what constitutes a storm can be difficult to identify over long time periods due to varying characteristics, said Sean Birkel, a research assistant professor at UMaine’s Climate Institute. Some are primarily wind events, some bring heavy rain or snow, and some bring both. Historically, the documentation of such storms has been inconsistent, which can make it more difficult to discern longer trends and say for sure whether storms are growing more frequent.
But there has been an emerging pattern in North America in the past decade or so of more extreme weather events, Birkel said, and the autumn storms in Maine in recent years seem to be consistent with that. An Oct. 30, 2017, “bomb cyclone,” which knocked out power for nearly half a million electricity customers in Maine, stands out, he noted.
But whether they are part of a longer-term trend in Maine or an anomaly is not clear, he said.
“There needs to be more research done,” Birkel said.
The circulation of air patterns over North America appears to have changed “a little bit,” Birkel said, and more blocking patterns — in which adjacent masses of relatively cold and warm air are kept separate — seem to be occurring. This can cause wider differences in air temperatures in those masses that, in turn, produce stormier conditions when those blocking patterns break down and the air masses mix.
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“The North Atlantic is very warm right now,” Birkel said, adding that air temperatures are relatively cool over much of the eastern two-thirds of the U.S. “That’s helping to fuel intense storm activity across the country. The steeper the temperature [difference], the more instability there is.”
Wednesday’s storm, which had strong winds out of the south, was not a nor’easter, which has winds blowing from the other direction, said James Simko, a meteorologist with the National Weather Service in Caribou. The number of power outages could be because of the southerly wind direction, which some observers think causes more damage to trees in Maine because the trees are more accustomed to northerly winds, he said.
Around 1 to 1.5 inches of rain fell in northern Maine, but that rainfall has not done much to alleviate the lack of precipitation in Maine, he said. Scientists have attributed those drought conditions to the changing climate.
“It was definitely not a drought buster,” Simko said.