A lesser-known type of winter storm is occurring with greater intensity, threatening Maine’s coast, experts say.
Though winter storms known as nor’easters are commonly forecasted and experienced around the Northeast, a sister storm known as southeasters can bring nearly hurricane-level winds and storm surges that have been less common in the winter — until now.
There isn’t much data yet on how often these types of storms occur or if the amount of them is increasing, but scientists are continuing to research them and hope more information will help Mainers better prepare for the winds and floods that the storms bring.
While Southeasters aren’t new — the 2017 windstorm that knocked out power to much of the region and delayed Halloween was a southeaster — scientists are gathering new data that is helping to differentiate these storms from other winter storms like nor’easters.
Southeaster storms are a type of cyclone just like nor’easters, said Sean Birkel, Maine state climatologist and assistant professor at the University of Maine Climate Change Institute and Cooperative Extension. Cyclones rotate around a center point — always counterclockwise in the Northern Hemisphere.
What gives a southeaster its name isn’t the direction the storm is rotating but from where the storm hits the Northeast.
Nor’easters tend to come from the east across the Gulf of Maine, while the center of southeasters tend to approach from over New York, hitting the Northeast region from the west, Birkel said. This means the winds hit Maine from the southeast rather than the northeast.
The wind from southeasters can be stronger than nor’easters, Birkel said, because the winds hit from over the water. With no terrain to slow the gusts down, it picks up over the Atlantic and hits the coast harder than nor’easters. Southeasters can clock winds up to around 70 mph, Birkel said.
“There’s a station in Old Town just north of where I am now that recorded a gust of 70 to 72 [mph during the 2017 southeaster]. And I would believe it because I was looking out the window and there was a five minute period where it looked like a hurricane,” Birkel said.
Wind blowing into the coast causes a storm surge, which can be particularly harmful to the Maine coast. Water rises on top of high tides, said Peter Slovinsky, Marine Geologist with the Maine Geological Survey, and with nowhere to go in the bays and inlets that scatter the Maine coast, the water can stack up.
In addition to the 2017 wind storm, in 2019, there were intense storms two weeks apart in October and November that also damaged infrastructure. Two of these storms were also considered bomb cyclones — storms that rapidly intensify.
“These were very impactful events. It was quite striking to have three storms of this magnitude in two years time, two of which were within two weeks of each other,” Birkel said.
There isn’t any data yet on whether winter cyclones are getting more or less frequent, Birkel said, but because of unstable temperatures from the jet stream due to climate change, these southeasters are getting even more extreme.
The jet stream is experiencing more frequent “blocking patterns,” Birkel said, which means there are rises and troughs in the stream itself. As it becomes unstable with climate change, different gusts of cold air and warm air can create extreme weather.
“Windstorms could be a type of extreme that we might see more in the future,” Birkel said. “But part of this relates to the timing. There may be certain seasons in which we see these extremes express more than other seasons. But the atmospheric circulation that is associated with extreme weather, those are changing as the climate warms.”
The best thing Mainers can do is to be prepared.
In addition to the normal winter storm preparation Mainers can do, there are other ways to prepare for a storm with heavy winds and flooding such as bringing in things from outside like decorations and shovels that could get blown around in high winds, said Vanessa Corson, public information officer for the Maine Emergency Management Agency.
In other areas, where hurricanes are common, residents are often instructed to board up windows when the high wind events approach. That’s not something that happens in Maine — yet, Corson said. It’s not yet clear whether hurricane preparations common in more southern states will be necessary for future southeasters either or how older Maine houses might fare in storms with heavier winds.
As the storms get more intense, Mainers may have to learn whole new ways of being prepared in winter.
