Heavy Snow — Northern Coos, New Hampshire

2019-01-09 · Northern Coos, New Hampshire

Event narrative

A band of heavy snowfall developed on the morning of the 9th and pivoted over the North Country. Snow accumulations reached 6 inches or more by midday. Low pressure moving into New Brunswick kept winds northwest over the area into the overnight, and low level moisture forced over the mountains resulted in additional upslope snow accumulation.

Wider weather episode

Overnight on the 8th a warm front lifted into the Northeast and stalled along the coast. A strong upper level vorticity maximum crossed the the stalled boundary on the morning of the 9th and led to rapid cyclogenesis along the New England coastline. Low pressure moved northeast along the Maine coast before moving into New Brunswick. While it was cold enough to snow in the mountains, warmer temperatures in the low to mid levels allowed for precipitation to begin as a mix of sleet, freezing rain, and rain to the south. As low pressure strengthened, heights aloft lowered and precipitation transitioned to heavy snow as it exited the area. Low level moisture and northwest flow behind the departing system kept upslope snow showers going into the morning of the 10th.

Source: NOAA Storm Events Database, event_id 794288. Narrative written by the NWS forecast office that issued the report.