The severity of the Ice Storm of 1998 was the result of a confluence of very rare conditions, said Stephen Baron, a meteorologist with the National Weather Service in Gray.
As with any ice storm, the temperature at ground level was at or below freezing while the air above was warmer. But in the case of the 1998 event, there was one weather system causing freezing rain to fall and accumulate in Maine and the surrounding region and another weather system off of the Atlantic coast that was blocking the first weather system from moving out.
That led to three days of freezing rain that resulted in ice as thick as 3 inches to build up on trees and power lines.
“Meteorologically, all the right ingredients came together for this rare event,” Baron said.
But could it happen again? And is climate change making it more likely?
The combination of weather systems that resulted in the destructive 1998 ice storm could come together again with similar outcomes, but there is no evidence that climate change will increase the severity of ice storms or the frequency of extreme events like the one 25 years ago, said Maine State Climatologist Sean Birkel.
“Based on the available studies that have been conducted on ice storm frequency in the United States and elsewhere and the possibility for changes in the future, it’s unclear whether these significant, very impactful ice storms will become more or less common,” Birkel said.
At the same time, there is limited research that indicates milder freezing rain events – ones that last at most a few hours – will become more common, said Birkel.
In order for an ice storm to develop, there has to be a layer of warm air above a layer of colder air at ground level where the temperatures is at or below freezing. That structure causes precipitation to fall as rain and then to freeze to ice as it hits the ground.
Because global temperatures are generally rising but cold air from the Arctic still sometimes pushes into lower latitudes, there are some areas, including Maine, that have the potential for more small freezing rain events. What’s less clear is whether climate change increases or decreases the chances that one of those storms will stall and cause ice to accumulate over a period of days.
Birkel said more research is needed on the relationship between extreme and minor freezing rain events and climate change to better predict what the future of ice storms will look like.
Staff Writer Joe Lawlor contributed to this story.
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