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.

Winter Storm in NORTHERN WESTCHESTER, NEW YORK
From 16-DEC-20 18:00:00 to 17-DEC-20 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

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.

Winter Storm in NEW YORK (MANHATTAN), NEW YORK
From 16-DEC-20 16:00:00 to 17-DEC-20 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Official NWS Observation at Central Park, NY was 10.5 inches of snow. The Central Park ASOS measured a 40 mph wind gust at 5:51 am on December 17, 2020.

Winter Storm in SOUTHERN NASSAU, NEW YORK
From 16-DEC-20 15:30:00 to 17-DEC-20 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

A CoCoRaHS observer measured 7.6 inches of snow 1 mile east of Searingtown, NY. An NWS Employee in East Meadow measured 6.2 inches of snow. Trained spotters and the public reported 5 to 8 inches of snow. Much of this snow fell before a brief changeover to a mix of rain and sleet. Any snow melt and standing water quickly refroze during the Thursday December 17, 2020 commute as temperatures fell below freezing creating hazardous travel. Additional light snow accumulation also occurred during the morning commute. The Farmingdale Airport ASOS measured a 49 mph wind gust at 7:53 am on December 17, 2020. The Wantagh New York Mesonet station measured a 48 mph wind gust at 6:30 am on December 17, 2020.

Winter Storm in NORTHERN NASSAU, NEW YORK
From 16-DEC-20 16:00:00 to 17-DEC-20 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotters in Syosset and Melville reported 8 inches of snow. The nearby Farmingdale Airport ASOS measured a 49 mph wind gust at 7:53 am on December 17, 2020. The nearby Wantagh New York Mesonet station measured a 48 mph wind gust at 6:30 am on December 17, 2020.

Winter Storm in SOUTHWEST SUFFOLK, NEW YORK
From 16-DEC-20 16:00:00 to 17-DEC-20 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Official NWS Observation at the Islip Airport was 7.4 inches of snow. The Islip Airport Observer also measured a 2 Inch per hour snowfall rate between 8 pm and 9 pm on December 16, 2020. NWS Employees, trained spotters, and the public reported 4 to 8 inches of snow. The snow changed to a brief mix of rain and sleet, then predominately rain during the early morning hours on December 17, 2020. The rain then changed back to snow during the morning commute.  Any snow melt and standing water quickly refroze during the commute as temperatures fell below freezing creating hazardous travel. Additional light snow accumulation also occurred during the morning commute.  The Islip Airport ASOS measured a 51 mph wind gust at 8:56 am on December 17, 2020. The nearby Farmingale Airport ASOS measured a 49 mph wind gust at 7:53 am on December 17, 2020.

Winter Storm in NORTHEAST SUFFOLK, NEW YORK
From 16-DEC-20 17:00:00 to 17-DEC-20 16:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

COOP Observers and an NWS Employee reported 5 to 7 inches of snow. The snow changed to a brief mix of rain and sleet, then predominately rain during the early morning hours on December 17, 2020. The rain then changed back to snow during the morning commute. Any snow melt and standing water quickly refroze during the commute as temperatures fell below freezing creating hazardous travel. Additional light snow accumulation also occurred during the morning commute. The Southold New York Mesonet station measure a 56 mph wind gust at 2:05 am on December 17, 2020.  Winds gusted to 48 mph at the nearby Westhampton Beach Airport ASOS at 9:53 am on December 17, 2020.

Winter Storm in PUTNAM, NEW YORK
From 16-DEC-20 18:00:00 to 17-DEC-20 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotters in Mahopac and Brewster reported 13 and 11.7 inches of snow respectively.  Broadcast media, amateur radio, CoCoRaHS, and the public reported 9 to 11 inches of snow. The New York Mesonet station in Brewster measured a 36 mph wind gust at 8:55 am on December 17, 2020.

Winter Storm in BRONX, NEW YORK
From 16-DEC-20 17:00:00 to 17-DEC-20 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter 1 mile south of East Tremont measured 12.4 inches of snow. The public also reported 9 to 12 inches of snow. The New York Mesonet station in Fordham measured a 43 mph wind gust at 5:40 am on December 17, 2020.

Winter Storm in NORTHERN QUEENS, NEW YORK
From 16-DEC-20 17:00:00 to 17-DEC-20 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Official NWS Observation at the LaGuardia Airport was 10.1 inches of snow. Trained spotters and the public reported 7 to 11 inches of snow. The LaGuardia Airport ASOS measured a 48 mph wind gust at 12:51 am on December 17, 2020.

Winter Storm in SOUTHERN QUEENS, NEW YORK
From 16-DEC-20 15:00:00 to 17-DEC-20 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Official NWS Observation at the John F Kennedy International Airport was 7.2 inches of snow. Trained spotters and the public reported 7 to 9 inches of snow. The John F Kennedy International Airport ASOS measured a 43 mph wind gust at 5:51 am on December 17, 2020. The New York Mesonet station in Kew Garden Hills measured a 44 mph wind gust at 6:10 am on December 17, 2020.

Winter Storm in SOUTHERN WESTCHESTER, NEW YORK
From 16-DEC-20 18:00:00 to 17-DEC-20 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A COOP Observer in Shrub Oak measured 9 inches of snow. Trained spotters, CoCoRaHS, and the public measured 6 to 10 inches of snow. Winds gusted to 40 mph at the nearby Westchester County Airport at 6:56 am on December 17, 2020.

Winter Storm in RICHMOND (STATEN IS.), NEW YORK
From 16-DEC-20 15:00:00 to 17-DEC-20 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Broadcast media reported 6.7 inches of snow 1 mile west of Huguenot. CoCoRaHS and the public reported 6 to 7 inches of snow. The New York Mesonet station 1 mile west of Willowbrook measured a 43 mph wind gust at 5:55 am on December 17, 2020.

Winter Storm in KINGS (BROOKLYN), NEW YORK
From 16-DEC-20 15:00:00 to 17-DEC-20 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

An Emergency Manager in Bay Ridge measured 9.6 inches of snow.  Trained spotters and the public reported 6 to 9 inches of snow. The New York Mesosnet station 1 mile south-southwest of Flatbush measured a 48 mph wind gust at 5:10 am on December 17, 2020.

Winter Storm in NORTHWEST SUFFOLK, NEW YORK
From 16-DEC-20 16:00:00 to 17-DEC-20 14:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

CoCoRaHS observers in 1 mile south-southwest of Nesconset and in Port Jefferson Station measured 8 inches of snow and 7.2 inches of snow respectively. Trained spotters, COOP Observer, and the public reported 6 to 8 inches of snow. Much of this snow fell before a brief changeover to a mix of rain and sleet. Any snow melt and standing water quickly refroze during the Thursday December 17, 2020 commute as temperatures fell below freezing creating hazardous travel. Additional light snow accumulation also occurred during the morning commute.  Winds gusted to 51 mph at the nearby Islip Airport ASOS at 8:56 am on December 17, 2020.  The Stony Brook New York Mesonet station measured a 45 mph wind gust at 11:05 pm on December 16, 2020.

Winter Storm in ORANGE, NEW YORK
From 16-DEC-20 17:00:00 to 17-DEC-20 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

A CoCoRaHS observer 1 mile south of Walden measured 14 inches of snow. Trained Spotters, Fire Department/Rescue and the public reported 11 to 14 inches of snow. Winds gusted to 38 mph at the Stewart International Airport at 10:45  am on December 17, 2020.

Winter Storm in ROCKLAND, NEW YORK
From 16-DEC-20 18:00:00 to 17-DEC-20 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Amateur radio reported 10 inches of snow 1 mile north-northwest of Pomona. Trained spotters and the public reported 6 to 10 inches of snow. Winds in nearby Orange, Putnam, and Westchester counties gusted 35 to 40 mph the morning of December 17, 2020.

Winter Storm in SOUTHEAST SUFFOLK, NEW YORK
From 16-DEC-20 17:00:00 to 17-DEC-20 16:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

The public reported 4 to 7 inches of snow. The snow changed to a brief mix of rain and sleet, then predominately rain during the early morning hours on December 17, 2020. The rain then changed back to snow during the morning commute. Any snow melt and standing water quickly refroze during the commute as temperatures fell below freezing creating hazardous travel. Additional light snow accumulation also occurred during the morning commute. Winds gusted to 48 mph at the Westhampton Beach Airport ASOS at 9:53 am on December 17, 2020. The Shirley Airport ASOS measured a 44 mph wind gust at 9:56 am on December 17, 2020.