Sean Birkel noticed that a fairly significant storm was headed toward Vermont, but it wasn’t until the National Weather Service issued warnings over the July 8 weekend about a high risk of excessive rainfall that he began analyzing the predictions more closely.
“I didn’t think it would be this extreme,” said Birkel, who is Maine’s state climatologist and a professor at the University of Maine’s Climate Change Institute. “Most people were surprised.”
If the highly concentrated storm that Vermont saw earlier this week had shifted slightly east, it would have brought similar flooding to Maine. That is especially the case in the western parts of the state that have similar topographies to Vermont, with residents often living in valleys near rivers.
Scientists expect such geographically focused storms to happen more frequently in the future as a changing climate affects regional precipitation. Almost a quarter of Maine’s infrastructure facilities are already at risk of disabling floods, according to the nonprofit First Street Foundation, which assembles climate risk data. Maine needs to plan for severe flooding beyond its coast to inland valleys and rivers, it said.
“If this particular weather system had the plume of moisture just a little farther to the east, Maine would have had more impacts,” Birkel said. “It gives us pause that a precipitation event of that magnitude could happen here.”
By Monday, the storm was dumping near-record rains over large swaths of Vermont, New York’s Hudson Valley and parts of Quebec, with flash floods damaging homes, businesses, roads and farms.
The first two days dropped up to nine inches of rain on some small Vermont mountain communities, according to the Burlington Free Press, cutting access to roads and essential services. Birkel and other scientists are comparing the effects of the storm to those of Hurricane Irene in 2011, which caused extensive damage in Vermont. The hurricane killed 40 people in 11 states and caused $6.5 billion in damages, according to the NWS.
Scientists are predicting more frequent intense storms. Birkel, other scientists and state policymakers are trying to prepare for them. The Maine Climate Council plans to start updating the state’s climate action plan starting on Sept. 29, with a goal of completing it by the end of next year.
Birkel, who is on the council, said the plan will take into account new precipitation models from First Street that show so-called 100-year storms may now occur far more frequently than previously predicted because of warming water bodies and clouds retaining more moisture.
The Earth’s atmosphere retains 7 percent more water vapor for every 1.8 degrees Fahrenheit its temperature rises, and that is creating a tremendous amount of risk for more severe storms and flooding, Jeremy Porter, head of climate implications at First Street, said. That is why the foundation created a new model for predicting storms. The National Oceanic and Atmospheric Administration model that has been used by scientists and weather forecasters for decades is out of date with the changing climate. NOAA said last December that it plans to update its precipitation forecasts, but those will not be completed until 2027.
Using First Street’s model, which accounts for climate change, Bangor is expected to have a storm with major precipitation every 32 years, or three times more likely than the NOAA prediction of a major rain storm every 100 years, he said.
“That’s a problem because we are building our stormwater infrastructure, buildings and properties to manage the risk of the 100-year storm, but the risk is actually 30 percent higher,” he said.
First Street’s models show areas across the midwest and northeast where the amount of risk has been underestimated. In Maine, Eastport, Bar Harbor and Gray are among the areas facing risk of a major storm every 10 years so they would not be prepared adequately if they planned using the NOAA model.
Flash flooding in Maine is more likely to occur in higher elevation areas with steep slopes, along streams, in the floodplains of rivers and streams, in low-lying areas with poor drainage and in urban areas with impervious surfaces, Ryan Fordon, hydrologist with the Maine Geological Survey, said.
Clockwise, from left: Route 133 in the Franklin County town of Jay closed Thursday after severe flooding in June led to a washout. Credit: Courtesy of the Maine Department of Transportation; A UPS truck is parked on flooded street on the waterfront while making deliveries during a powerful winter storm, Friday, Dec. 23, 2022, in Portland, Maine. Credit: Robert F. Bukaty / AP; Kaylee Collin, right, and Spencer Stone walk through water along North Avenue in Camp Ellis in Saco, Maine on Sunday, March 4, 2018. Credit: Gregory Rec / Portland Press Herald via AP.
“Still, no place is completely immune when rainfall rates are intense,” he said.
Areas of Maine are at risk for flash flooding in the summertime due to intense precipitation events, and river flooding in the winter and spring due to rain-on-snow events and ice jams. The causes of these two types of flooding are different and can affect different parts of the state.
Because of slightly different patterns of geography, human settlement and infrastructure, Maine is not as susceptible to the ill effects of flash flooding as some parts of Vermont, but it can certainly happen here, he said.
Recent examples where prolonged heavy rains hit already soaked ground and caused massive flooding similar to that in Vermont are the destructive flash flooding in Andover from June 25-26 and in Jay and Wilton on June 29.
Much of the flood risk triggered by excessive rainfall can be avoided by preventing development in floodplains, said Sam Roy, natural hazards planner with the Maine Department of Defense, Veterans and Emergency Management. State laws and local floodplain ordinances prevent most types of development in flood-prone areas.
The Maine Emergency Management Agency recommends that Mainers plan for a possible evacuation and have two possible routes in case one floods. People also should plan for their pets and family members needing medical attention. There are several websites to find out whether your home is susceptible to flooding, including the Floodplain Management website or First Street’s Risk Factor.
