Flash Flood — Cheshire, New Hampshire

2012-05-29 · near Nelson, Cheshire, New Hampshire

Event narrative

Numerous roads flooded in Keene (including Maple and Pako Avenues, Roxbury, Church, Harrison, Gurnsey, and Edwards Streets, Hurricane and Belvedere Roads, and Colonial and Dale Drives), Westmoreland (including Mount Gilboa Road), Sullivan (including Centre Street, Route 9, and South, Hubbard, and East Sullivan Roads) and Gilsum (including Route 10 and Vessel Rock Road). Centre Street in Sullivan and Vessel Rock Road and Route 10 in Gilsum were washed out. Ferry Brook in Keene was out of its banks. Route 9 in Sullivan was closed with cars stuck in the floodwaters. In Keene, Belvedere Road off Route 10 sustained the most damage. Several roads in Keene sustained washouts: including Old Walpole Road (1,000 feet), East Surry Road (culvert), Ferry Brook Road (200 feet), and White Brook Road (200 feet). Route 9 and Route 12 were both closed for a period of time due to the flooding. Route 12 was damaged on the northbound side between the Summit Steakhouse in Westmoreland and the Black Brook Industrial Park in Keene. These closed roads cut off some residents, making travel between Westmoreland, Keene, Gilsum, and Sullivan difficult, if not impossible. A quarter mile section of Centre Street in Sullivan was completely washed out with lesser damage over a mile long length.

Twenty six people stayed in a Red Cross shelter Tuesday night (May 29), only 1 remained Wednesday night (May 30). Basements flooded across Keene, some with up to 4 to 5 feet of water. Flooding resulted in Gilsum and Sullivan Elementary Schools being closed Wednesday (May 30) because access to those schools was limited by closed roads.

Wider weather episode

A warm front moved through southern New Hampshire early Tuesday morning, leaving the area in a very moist, warm, and unstable airmass. Tuesday afternoon a cold front began moving across western New York and approaching southern New Hampshire. As the front made its way across this area, it set off showers and thunderstorms across much of eastern New York and western Massachusetts in an especially moist environment. These storms eventually moved over parts of southern New Hampshire. Three high precipitation supercell thunderstorms moved in the same path over central Cheshire County.

These thunderstorms each produced two to three inches of rain, with most of it falling over Surry, Gilsum, and Keene and to a somewhat lesser extent over Sullivan, Walpole, and Westmoreland. The NWS cooperative observer at Surry Mountain Dam recorded 6.91 inches of rain total, while the Taunton WSR-88D radar estimated storm total rainfall of up to 8 to 9 inches in less than a couple of hours. This resulted in flash flooding across much of this area.

View location on OpenStreetMap → (42.9826, -72.1527)

Source: NOAA Storm Events Database, event_id 386917. Narrative written by the NWS forecast office that issued the report.