A series of February snowstorms have piled up the snow in the mountains of Vermont heading into the last month of winter and emergency planners and weather forecasters are starting to prepare for the possibility of flooding when that snow starts to melt.
The National Weather Service has begun issuing bi-weekly reports on the spring flooding threat. Currently the threat is rated at near or slightly above normal. Everything depends on what happens over the next six weeks.
“The spring flood threat really has a lot to do with what happens from basically mid-February through April,” said Scott Whittier of the NWS office in South Burlington.
In a worst case, Vermont could see a repeat of 2011, when heavy winter snows and spring rains kept Lake Champlain well above flood stage until late June. It was a foretaste of the catastrophic statewide flooding caused later that year by Tropical Storm Irene.
In 2001 officials warned that a heavy winter snowpack would almost certainly combine with spring rains and warm temperatures to flood low-lying areas. But the weather cooperated and there was no flooding that year.
Following four separate flood emergencies in 2011, including Irene, and three last year, people at Vermont Emergency Management and Homeland Security are also starting to watch the flood forecast, said spokesman Mark Bosma.
“It’s always top of mind at certain times of the year and this is one of them. We’ve always been curious and interested in what the flood forecast is. It could be a case where people are just noticing it more because of Irene and that whole awful 2011,” he said.
Even though there have been several large snowstorms in recent weeks, for the season the snowfall measured at the Burlington International Airport is near normal. But in 2011 there were major storms in March.
The flooding danger will escalate if the snow continues to fall and it starts to melt all at once, especially if it’s accompanied by heavy spring rains, Bosma said.
Vermonters could be more sensitive to the threat of flooding, given the four major floods of 2011 and three from 2013.
“There is always going to be some version of a snowmelt threat, whether it’s localized ice jams or whether it’s a big event like 2011,” Whittier said.
“I think people have very short memories, thus if they are impacted, they are more likely to be responsive, which may actually be a good thing,” Whittier said.
At the beginning of April 2001, there was the equivalent of 10 inches of rain held in the snow in the mountains. But major flooding was avoided when the weather warmed slowly and there were no major rain storms. Three years ago, the heavy winter snows combined with heavy spring rains to push Lake Champlain above flood stage until June 20.
It was just over two months later when Tropical Storm Irene hit the state.
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