Flood in Somerset County, Maine

Major to near record flooding occurred on the Kennebec River downstream of Bingham following heavy rain and snowmelt on December 18th. Heavy rain fell across the entire Kennebec Valley, however it was the combination of rain and snowmelt runoff in the mountains that caused catastrophic flooding across the region. Wyman Dam limited damage in Bingham apart from some of the local streams. Further downstream in Solon the flood waters inundated properties along Main Street. On the west side of the river flooding occurred across Embden near the Route 201 bridge. The USGS river gage at Madison surpassed the flood of 1987 cresting at 26.7 feet. The streamflows were 134 kcfs, surpassing the 0.2% annual chance flood level, otherwise referred to as the 500 year flood.

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.