Flood — Somerset, Maine

2023-12-18 to 2023-12-19 · near Great Works, Somerset, Maine

Event narrative

The Carrabassett River Valley experienced catastrophic flooding following a heavy rain and snowmelt event on December 18th. The rain fell over an 18 hour period and averaged 5 inches across the basin, with an additional 2 to 3.5 inches of snowmelt. The steep terrain and frozen ground supported rapid runoff with all streams becoming raging torrents. The USGS river gage on the Carrabassett River in North Anson climbed from 5 feet to 26.64 feet in 24 hours, narrowly missing the all time record stage of 26.66 feet set in 1987. This was the second highest crest ever recorded since the gage was established in 1929. The streamflows were measured over 50 kcfs, which exceeds the 0.2% annual chance flood, otherwise referred to as a 500 year flood. It is estimated that the runoff caused flows of at least 500 year levels within the tributaries to the Carrabassett River including Stoddard Brook, Poplar Stream, Huston Brook, Alder Stream, Nash Brook, Stratton Brook, Redington Pond Outlet, and several others. Several dozen properties including homes and businesses were flooded and damaged during the event, with millions of dollars in damages. All major thruways were flooded and washed out, notably Routes 27 and 16, with citizens cut off for days. Several bridges were overtopped including Claybrook Road Bridge, Stratton Brook Bridge, and Redington Stream Bridge in Carrabassett Valley. Smaller local bridges were damaged or washed-out, including Poplar Mountain Road, Long Falls Dam Road, Gauge Road, Huston Road, and Alder Stream in Carrabassett Valley. Numerous swift water rescues were necessary to remove residents and motorists from flood waters. Water rescues occurred in New Vineyard to remove people from flooded buildings. Though official damages were not available at the time of this report, it is estimated that they exceeded $5 million.

Further downstream in Kingfield, several portions of Route 27 were flooded including the Route 16 bridge. Homes on Island Road were flooded after floodwaters cut off access to the community. Properties on the east bank of the Carrabassett River along Riverside Street near Indian Stream Road were flooded, along with others off Katie Crotch Road in East New Portland. In North Anson, there were 14 homes flooded on River Road and an additional 6 on Madison Street. Rapid Stream, a tributary to the South Branch of the Carrabassett River, overtook Rapid Stream Road causing 2 miles of washouts and the loss of 2 bridges. The West Branch Carrabassett River flooded Route 142 near McClures Tree Farm with flood waters knee to chest deep.

Wider weather episode

Low pressure began organizing in the Gulf of Mexico on the 16th, setting record low sea level pressures as it traversed the Southeast through the 17th. Strong high pressure over the North Atlantic created a deep southeasterly flow that drew warm air into New England ahead of the approaching storm. By the time precipitation arrived on the evening of the 17th, temperatures were warm enough for rain everywhere except the highest peaks. Early on the 18th a shortwave trough was approaching from the Great Lakes and led to rapid deepening of the low pressure as it paralleled the Eastern Seaboard. Even as the center of the storm remained near Chesapeake Bay on the morning of the 18th, a strong low level jet had developed and winds began to gust in excess of 50 mph well inland from the coast. Damaging wind gusts continued into the afternoon. Hundreds of thousands of customers lost power due to falling limbs and downed wires. The anomalously warm air mass also led to intense rainfall rates beginning on the evening of the 17th, which continued into the 18th. Upsloping winds also enhanced precipitation along the southeast facing slopes of the mountains. Widespread 3 to 4 inches of rain fell, with isolated pockets of 6 to 8 inches. This fell on top of snow that was ripe from previous rainfall about a week earlier. An additional 2 to 3 inches of snow water equivalent was likely added to rainfall runoff. Numerous road washouts and road closures occurred due to flash flooding and fast responding small stream and tributaries. Widespread moderate to major flooding occurred along mainstem rivers. The storm destroyed 13 homes, caused major damage to 106 others, with an additional 65 homes receiving minor flood damage. Private damage was in the millions with public infrastructure damage of 20+ million being reported by FEMA.

View location on OpenStreetMap → (44.8919, -70.1631)

Source: NOAA Storm Events Database, event_id 1151021. Narrative written by the NWS forecast office that issued the report.