Coastal Flood — Coastal Rockingham, New Hampshire

2024-01-10 · Coastal Rockingham, New Hampshire

Event narrative

An intense and rapidly deepening area of low pressure over the Great Lakes region (975 mb) combined with modestly high astronomical tides to produce the third highest storm tide ever in Portland (records 1912-present). In the Portsmouth region at the relatively new Seavey Island gauge, the tide reached 12.46 feet (MLLW) at 9:36 am. The storm surge was recorded at 3.17 feet. The Hampton tide gage amazingly remained above flood stage for over four hours (from 805 am to 1215 pm), topping out at 13.56 feet (MLLW) with a storm surge of 4.16 feet near the time of high tide. This tide gage didn't have a long period record but the water level was the highest recorded since the install in 2012. Storm to hurricane force southeasterly winds occurred along the coast with nearshore waves of 15 to 20 feet. Major flooding was recorded from Seabrook to Rye with numerous roads closed due to flooding including Rt 1A. Over wash with debris and erosion was reported along the seashore due to large waves overtopping coastal infrastructure. Major inundation of homes, especially in the back bay area of Hampton Beach was observed with hundreds of homes being cut-off and surrounded by water at the time of high tide with water depths of 3 feet or more. The flooding was close if not the most significant ever recorded in the Hampton Beach area.

Wider weather episode

A powerful storm tracked northeast through the Mid Mississippi River Valley on the 9th, rapidly deepening as it approached the southern Great Lakes. Precipitation formed along and ahead of the advancing warm front, which arrived in part of northern New England during the evening of the 9th. High pressure anchored to the north of Maine dammed low level cold air up against the mountains and allowed precipitation to start as snow for most locations in New Hampshire, except for those east of the coastal front along the Seacoast. The coastal front was able to quickly mix westward as heavier precipitation moved into the area, and snow changed to rain into the foothills through midnight and the early morning hours. Rain closer to the coast and snow across the higher terrain was heavy at times through the overnight hours. Snowfall of 6 to 12 inches occurred in the higher terrain, with locally higher amounts in the high peaks. Rainfall was a widespread 2 to 4 inches where precipitation remained mostly rain. A strong low level jet accompanying the deep low pressure over the eastern Great Lakes arrived during the early morning hours on the 10th, with strong to damaging wind gusts along the Seacoast as well as on the northwest side of the White Mountains. These warm winds along with rainfall helped to melt much of the fresh snow pack that had fallen on the 7th. The strongest east southeast winds also arrived just ahead of high tide, as they were approaching their monthly spring tides. Moderate to major coastal flooding and large, battering waves occurred all along the Seacoast leading to major damage. By the morning of the 10th, snow, rain, and wind had all moved east of the area.

Source: NOAA Storm Events Database, event_id 1157927. Narrative written by the NWS forecast office that issued the report.