A flood watch is in effect in western Maine from late Monday night through Tuesday evening, the National Weather Service announced Sunday.
Rainfall of 1 to 1.5 inches is expected during those times and could cause flooding on rivers and small creeks. The weather service said there’s still “plenty of ice which may begin moving,” which could create ice jams and increase the threat of flooding.
Areas in the flood watch include Androscoggin, Cumberland, Waldo, York, Kennebec, Knox, Lincoln, Sagadahoc, Franklin, Oxford and Somerset counties.
Forecasters grade flood potential at above average statewide because of this winter’s heavy snowfall, including as much as 6 inches of snow in northern Maine on Saturday, said Chris Norcross, a meteorologist with the National Weather Service’s Caribou office.
“It’s difficult to forecast when the [river] ice will break up and move,” Norcross said Saturday. “One big rain event, one big warm-up and things could change very quickly under the right circumstances.”
Ice thickness measures 2 to 3 feet in northern and central Maine waterways, including the Allagash, Aroostook, Piscataquis, and St. John rivers. The Penobscot River and its tributaries, including the Mattawamkeag River, are opening up from Medway to Howland, showing signs of “ice rot,” and could “break free at any time,” meteorologists said.
Rivers further south and near the coast carry ice about a foot deep, which is thicker than average for this time of year.
The weather service, state police and county sheriffs reported no significant flooding or weather-related accidents on Saturday. The storm that started overnight Friday left 1 to 3 inches of snow from Bangor north to the Canadian border, with Pittston Farm, a town northwest of Moosehead Lake, reporting 6 inches of snowfall. The area from Moosehead Lake to Jackman and Rangely had 2 to 6 inches of snow, Norcross said.
Most of the snow fell on southern Piscataquis County, Aroostook and northern Penobscot counties, he said. The rest of the state got mixed precipitation that was expected to leave no more than an inch of rain in interior Maine and 1.25 inches along the coast, he said.
Rain, snowmelts and ice jams normally combine to cause flooding at this time of year, but deep snowpacks that remain on mountains and highlands, and below-freezing temperatures overnight, leave the state about two or three weeks behind its typical schedule, said Tom Hawley, a hydrologist for the National Weather Service office in Gray.
“We are just worried in this time of spring, kind of watching the weather. We hope we don’t get the 4 or 5 inches of rain that could really change things,” Hawley said.