Winter Storm — Northern Westchester, New York

2020-12-16 to 2020-12-17 · Northern Westchester, New York

Event narrative

A CoCoRaHS observer 2 miles east of Yorktown Heights measured 11 inches of snow and a CoCORaHS observer 2 miles south of Peach Lake measured 10.9 inches of snow. Amateur radio and trained spotters measured 10 to 12 inches of snow. Winds gusted to 40 mph at the Westchester County Airport at 6:56 am on December 17, 2020.

Wider weather episode

Low pressure developed along the Middle Atlantic coast on Wednesday December 16, 2020. The low deepened as it tracked northward towards Long Island, NY through the night on December 16, 2020. Arctic high pressure situated over southeast Canada provided a cold and dry air mass ahead of the low supporting moderate to locally heavy snowfall at the onset. The low pressure ultimately tracked from near Atlantic City, NJ to about 50 miles south of Fire Island, NY before sliding offshore Thursday December 17, 2020. This track led to warmer air aloft moving over the NYC metro and Long Island, changing the snow to a mixture of sleet and rain. Surface temperatures briefly warmed into the upper 30s across central and eastern Long Island early on December 17, 2020, changing the precipitation to plain rain. Once the low began moving away from Long Island, temperatures fell significantly below freezing with snow returning as the event ended. Any snowmelt and standing water refroze on Long Island. Any mixed precipitation was brief in the NYC metro and predominately snow fell across the Lower Hudson Valley. The storm significantly impacted travel during the evening commute on Wednesday December 16, 2020 and the morning commute on Thursday December 17, 2020. Many accidents resulted from the snow and icy conditions. Snowfall rates ranged from 1 to 2 inches per hour Wednesday evening. Total snowfall ranged from around 4 inches across coastal southeast Long Island to as much as 14 inches in Orange County. 6 to 12 inches of snow fell in the NYC metro. Strong wind gusts also occurred with the storm, 35 to 60 mph, with some coastal stations reporting gusts as high as 74 mph on Long Island.

Source: NOAA Storm Events Database, event_id 934935. Narrative written by the NWS forecast office that issued the report.