Flood — Franklin, Maine

2023-12-18 to 2023-12-19 · near Farmington Falls, Franklin, Maine

Event narrative

Near record flooding occurred on the Sandy River following a heavy rain and snowmelt event on the 18th. The rainfall across the headwaters of the Sandy was estimated between 5 and 6 inches, but it was the combination of this and an additional 3 inches of snowmelt runoff that caused the catastrophic flooding. The USGS river gage reached a stage of 12.79 feet on the late afternoon of the 18th, with a measured streamflow over 10 kcfs. The streamflows measured surpassed a 0.2% annual chance exceedance flood, otherwise referred to as a 500-year flood. The river rise went from 5 feet at midnight to over 12 feet by the early afternoon, breaking the previous record set after the remnants of Irene in 2011. The most significant impacts occurred in Farmington where several homes and businesses were flooded. Of particular severity were businesses along Front Street and Main Street where the water depth was chest deep. The confluence of the Temple Stream and Sandy River resulted in additional business and residential flooding necessitating evacuations and some destruction of property with flood waters up to 4 feet deep. Further downriver, into Farmington Falls, several homes were damaged and a new bridge construction was overtopped and damaged. Routes 2 and 41 were flooded and closed. The river washed out the Route 145 bridge in Strong. Route 4 was flooded in several locations between Sandy River Plantation and Farmington, cutting off the major thruway in the region. Numerous roads in Phillips were flooded or blocked off to include Ross Ave, Smiths East Madrid Road and the Number Six Road. Emergency officials declared Farmington 'essentially completely flooded' with all roads closed and issued a do not travel advisory for the region.

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 1151022. Narrative written by the NWS forecast office that issued the report.