Flood — Kennebec, Maine

2023-12-18 to 2023-12-22 · near (aug)augusta State A, Kennebec, Maine

Event narrative

On December 19th the Kennebec River at Augusta reached the 3rd highest level on record, cresting at 26.92 feet. The other floods of record were 30.70 feet in 1936 and 34.1 feet in 1987. The river stage in Augusta has significant tidal influence so the discharge varies based on the time of day, however using estimates from upstream gages it is likely the flows fell between a 50 to 100 year event, or 1-2% annual chance exceedance level. The flooding was the result of heavy rain combined with snowmelt from the headwaters. The most significant impacts were east of Water Street south of Bond Brook and along Front Street in downtown Augusta, just south of the Calumet Bridge. Businesses along Front Street observed flood waters chest high in first floor buildings, including a U.S. Post Office. Multiple homes flooded from the Kennebec River and backwater on Bond Brook along Water Street and Bond Street on the west side of the river. Flooding was less severe on the east bank where most of the inundation was in recreational areas and portions of Howard Street.

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 → (44.3200, -69.8000)

Source: NOAA Storm Events Database, event_id 1151030. Narrative written by the NWS forecast office that issued the report.