Flood — Oxford, Maine

2023-12-18 to 2023-12-20 · near Bethel, Oxford, Maine

Event narrative

Catastrophic flooding occurred in and around Bethel after a storm brought 7 to 10 inches of combined rain and snowmelt to the region. The Androscoggin River only reached minor flood stage at the upstream river gage in Gorham, yet the contribution of flows from the mountains in between the two towns were sufficient to cause the river to reach major flood levels. Estimates put the Androscoggin River flows somewhere between the 0.5 to 0.2% annual chance exceedance levels, otherwise referred to as the 200 to 500 year floods. The tributaries out of the mountains are estimated to have exceeded 500 year flood levels including the Moose Brook, Moose River, Peabody River, Wild River, and Sunday Rivers. The Mill Brook ran high and contributed to the flooding in Bethel, but was not the significant contributor when compared to the other sources. The combined flows caused severe damage to properties and roads in the community, isolating the area for days. The flooding was recorded as the 3rd highest in downstream Rumford, and estimated to be the 4th highest in Bethel since 1860. The floodwaters reached levels near, above, and just below high-water marks from the flood of 1987, though that flood had un-natural responses due to complications from river ice. Though streamflows were likely less than that of 1987, the reported damage was worse. The hardest hit part of the community was in town near the Kowloon Village and Bethel Wastewater Treatment facility, and north of the river along Interval Road and Route 2 & 5. Further downstream in Hanover, flooding was extensive including inundation at the town office off Route 2. About 7 businesses in Bethel sustained major flood damage. The cost of the damage to roads and infrastructure was estimated at $1 million. There were over a dozen homes damaged by flood water with a total cost estimated around $750,000.

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 → (44.4025, -70.7773)

Source: NOAA Storm Events Database, event_id 1151024. Narrative written by the NWS forecast office that issued the report.