Flood — Oxford, Maine

2023-12-18 to 2023-12-19 · near Bryon, Oxford, Maine

Event narrative

Record flooding occurred along the Swift River in Roxbury with a river crest at 14.2 feet, breaking the record of 12.87 feet set in October of 1959. The flooding was caused after 6 inches of rain and an estimated 2 inches of snowmelt caused the river to rise 12 feet in 16 hours. The streamflows measured over 21 kcfs had a 0.5 to 0.2% annual chance exceedance, otherwise referred to as a 200 or 500 year flood recurrence interval. The most significant damage occurred near the confluence of the Swift River and the Androscoggin River in Mexico and Rumford. Major flooding on the Androscoggin coincided with the timing of the peak flood wave on the Swift River. This resulted is destructive flooding between Carlton Avenue to Riverside Avenue including Route 2 in Mexico, and Rumford Avenue up to the Hosmer Field complex. A few dozen homes and businesses observed floodwaters several feet deep, with some properties condemned. Additional significant damage occurred in downtown Roxbury where the river came out of banks over Frye Crossover Road bridge, flooding all the way to Route 17 and up to the base of the Post Office and at flooding at least 4 separate residences. Route 17, a main thruway in the region was severely damaged in dozens of locations in the Byron and Roxbury area. The bridge over Coos Canyon was compromised on both the east and west sides. A home was flooded on Weld Road in Byron. A well-constructed snowmobile bridge was washed out in Byron.

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.

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Source: NOAA Storm Events Database, event_id 1151020. Narrative written by the NWS forecast office that issued the report.