Flood — Hillsborough, New Hampshire

2007-04-16 to 2007-04-18 · near Peterborough, Hillsborough, New Hampshire

Event narrative

Flooding closed part of Route 202 in Peterborough, Route 122 and South Merrimack Road in Hollis, and widespread urban flooding in Nashua and Manchester. A mudslide closed a portion of Route 101 in Wilton. Minor to moderate flooding was observed on the larger mainstem rivers. The Merrimack River at Nashua crested at 23.5 feet at 8 am on the 17th (flood stage is 18 feet), while at Goffs Falls the Merrimack crested at 16.8 feet at 1 pm on the 17th (flood stage is 11 feet). The Contoocook River at Peterborough crested at 7.2 feet at 1 pm on the 16th (flood stage is 5.5 feet. The Souhegan River at Merrimack crested at 12.7 feet at 545 am on the 17th (flood stage is 9 feet).

Wider weather episode

An unusually strong and slow moving coastal storm for mid April tracked to western Long Island Sound, before weakening slowly and drifting offshore. This storm brought a variety of impacts to southwest New Hampshire, including heavy snow to the higher elevations and widespread river and stream flooding.

Snowfall totals as high as 4 to 8 inches were observed in the higher elevations of Cheshire County. There were numerous reports of downed trees and power lines in these areas from the weight of the heavy, wet snow.

Rainfall totals of 3 to 5 inches, combined with wet antecedent conditions, resulted in widespread river and stream flooding, as well as significant flooding of urban areas. The worst flooding affected the Merrimack Valley, where moderate to major flooding occurred on the Merrimack, Nashua, Piscataquog, and Souhegan Rivers. For many locations, this may have been the worst flooding since the May, 2006 or April, 1987 floods ' but along the Piscataquog and Souhegan Rivers the preliminary crests recorded may have been the highest since the floods of September, 1938.

Many small streams throughout the region also rose out of their banks and flooded nearby areas, including roadways. Significant flooding

occurred along small streams in Hillsborough County, where a portion of Route 122 was closed in Hollis and a mudslide closed Route 101 in Wilton.

View location on OpenStreetMap → (42.8700, -71.9300)

Source: NOAA Storm Events Database, event_id 27742. Narrative written by the NWS forecast office that issued the report.