This story was updated at 6 p.m.
Heavy rain across New Hampshire closed roads, cut power, and caused some residents to evacuate their homes Monday. In the state’s North Country and White Mountain regions, rain, high winds, and temperatures in the 60s melted snow, causing rivers with headwaters in the mountains to rise quickly and flood roads.
“This is going to be a historical river flooding event for this area,” said Jon Palmer, a meteorologist with the National Weather Service.
The National Weather Service is forecasting the Pemigewasset River in Plymouth will reach a major flood stage Monday evening around midnight. Palmer called that rare and impactful, and said it could lead to floodwaters up to 6 feet deep on Route 175A in Holderness.
Some areas on the southern edge of the White Mountains received up to four inches of rain. All three of the National Weather Service’s climate sites — in Concord, and in Portland and Augusta, Maine — hit their warmest temperature on record for Dec. 18. That warmth and rain, combined with winds from the Southeast, melted the snowpack in the mountains fast, Palmer said.
“That combination is a recipe for disaster for river flooding,” he said.
Corey Clark, who leads the state’s dam bureau, said that precipitation not only landed on snowpack, releasing more water into river systems, but it also landed on frozen ground.
“The ground has very little ability to soak up any of that runoff,” he said.
River levels were still rising in many places Monday night as rain continued falling, while rivers, like the Ammonoosuc, were beginning to crest.
A number of roads are still closed in New Hampshire after fallen trees, wires, and flooding issues, including NH-49 in Campton.
That road is next to a dam that was a cause of concern for some Monday. Clark, with the dam bureau, said it did not fail, but was operating as it should when there is an increased volume of water.
“When the water gets high at that location, it actually does flood the adjacent road,” he said. “The road is somewhat integral as part of the dam.”
State officials are adding “stop logs” on the road to control the flow of water, Clark said, to encourage the water to flow through the dam rather than down the road. As of Monday afternoon the water level was plateauing, and the dam appeared to be holding up fine.
A hydropower dam in Shelburne is also experiencing high water challenges, Clark said, and had to remove flashboards to allow more water through.
In Gorham, water flowed into a wastewater lagoon because a culvert was clogged on Route 16, but the lagoon had enough capacity to keep it from spilling over, Clark said.
Residents near the Beebe River have been asked to voluntarily evacuate, WMUR reports.
Woodstock Fire Chief John Mackay said parts of Route 112 and Route 175 were closed Monday, and the fire department evacuated two cabins that were experiencing flooding. He said they were watching for danger as floodwaters rose near large propane tanks, and may evacuate people in the area below those tanks if waters continued rising.
The state has partially activated its emergency operations center “to support communities that are experiencing damage from severe rain, flooding and wind.”
Officials are urging people to exercise caution, be alert for crews clearing debris and to never drive through flooded roadways. Drivers can monitor road closures at www.newengland511.org.
Outages
As of 6 p.m. Monday, about 14,000 people were without power statewide. The majority of those were Eversource customers.
State safety officials are reminding people to stay away from downed wires and to not run a generator indoors.
Closings
WMUR reports nearly fifty cancellations or delays into Tuesday, mostly in the White Mountains region. You can find a full list of closings and delays here.
