Debris Flow — Grafton, New Hampshire
2012-10-30 · near Lincoln, Grafton, New Hampshire
Event narrative
A man was standing 5 feet from the edge of a 10-15 ft high embankment at a building site located on the steep slope of a mountain. Heavy rains from Sandy caused the embankment to collapsed causing a mudslide. The victim was caught in the mudslide and was washed into a ravine along with mud and boulders. Cause of death was attributed to blunt trauma to the head and suffocation due to the inhalation of mud and water.
Wider weather episode
On Monday, October 29th, Hurricane Sandy (and its remnants) tracked northwest from well off the North Carolina coast to southeastern Pennsylvania, making landfall near the southern tip of New Jersey. A band of heavy rain and high winds associated with Sandy moved northward into New Hampshire Monday afternoon and continued moving northward through the State Monday night. The high winds associated with this band of heavy rain downed numerous trees and caused widespread power outages. In addition, the heavy rains caused some road washouts in the State. By Tuesday, the remnants of Sandy had moved into western Pennsylvania, but the circulation around the weakening storm continued to bring tropical air into the region during the day Tuesday and into Wednesday. Localized heavy showers and thunderstorms developed in this tropical airmass Tuesday and Tuesday evening. Several of these thunderstorms produced damaging winds Tuesday evening. The shower activity diminished during the day Wednesday as cooler air moved into the region.
Winds across much of the State generally gusted from 40 to 70 mph Monday and Monday night. These strong and persistent winds combined with the powerful gusts to down numerous trees throughout the State and caused widespread power outages, especially across southern New Hampshire. Some peak wind gusts included 70 mph in Goshen, 62 mph in Londonderry, 60 mph in Portsmouth and Meredith, and between 50 and 60 mph in Concord, Derry, Newington, Fremont, and Rochester. Mount Washington had a gust of 136 mph and the Isles of Shoals gusted to 76 mph. In addition, on Tuesday, thunderstorm wind downed trees and produced damage in Northfield, Franklin, Andover, Plymouth, Meredith, and Canaan.
The most significant hydrological impact from the storm was due to the band of heavy rain that fell between Monday afternoon and Tuesday morning. Across the State, this band produced 1 to 3 inches of rain in about a 6- to 12-hour period. This amount of heavy rain in the short duration caused some road washouts in the State. In the southeastern side of the White Mountains, rainfall totals during the 12-hour period were between 3 and 5 inches. Over the 48-hour period from 8 am Monday to 8 am Wednesday, rainfall Sandy totaled from 2 to 4 inches across much of the State with the southeastern slopes of the White Mountains generally reporting from 3 to 6 inches. One reporting site in Gorham reported more than 8 inches of rain during the 48 hour period. One man was killed in a mudslide caused by heavy rain. He was standing 5 feet from the edge of a 10-15 ft high embankment at a building site located on the steep slope of a mountain. Heavy rains from Sandy caused the embankment to collapsed causing a mudslide. The victim was caught in the mudslide and was washed into a ravine along with mud and boulders. Cause of death was attributed to blunt trauma to the head and suffocation due to the inhalation of mud and water.
Minor flooding was also reported on a couple rivers in the State. In Conway, the Saco River rose to 10.59 feet, 1.59 feet above flood stage. In Woodstock, the Pemigewasset River rose to 10.06 feet, 1.06 feet above flood level.
Severe convection developed across southern New Hampshire Tuesday evening, the 30th, and knocked over trees and/or caused damage in Meredith, Plymouth, Canaan, Andover, Franklin, and Northfield.
View location on OpenStreetMap → (44.0561, -71.6659)
Source: NOAA Storm Events Database, event_id 416315. Narrative written by the NWS forecast office that issued the report.