Snow fell across the northern half of New Jersey from the evening of the 20th into the early morning of the 21st and a wintry mix of snow, sleet and freezing rain fell across southwest New Jersey during the early morning of the 21st. Mainly rain fell across southeast New Jersey. Snowfall averaged 1 to 2 inches in southwest New Jersey and 3 to 5 inches in the northern half of New Jersey. Ice accretions were less than one tenth of an inch.
Snow began in far northwest New Jersey during the evening of the 20th and slowly spread to the south, beginning in the southwest part of the state shortly after Midnight EST on the 21st. Precipitation fell as rain in the southeast part of the state. During the early morning, precipitation mixed with sleet and freezing rain in the southwest part of the state. In the northern part of the state, the snow fell at its heaviest around 3 a.m. EST. The snow ended between 5 a.m. EST and 7 a.m. EST. Its greatest impact was on the morning commute in the northern part of the state.
Representative snowfall included 4.8 inches in Marcella (Morris County), 4.5 inches in Blairstown (Warren County), 4.2 inches in Pottersville (Somerset County), 4.0 inches in Butler (Morris County) and Wantage (Sussex County), 3.5 inches in Flemington (Hunterdon County), Belle Mead (Somerset County) and East Brunswick (Middlesex County), 3.0 inches in Freehold (Monmouth County), 2.5 inches in Yardville (Mercer County), 1.6 inches in Delran (Burlington County), 1.5 inches in Verga (Gloucester County) and 1.3 inches in Pennsauken (Camden County).
The snow and wintry mix were caused by a developing low pressure system that formed in the Tennessee Valley during the afternoon of the 20th and moved northeast. It reached West Virginia at 7 p.m. EST on the 20th, the lower Susquehanna Valley in Pennsylvania at 1 a.m. EST on the 21st, right over Atlantic City, New Jersey at 4 a.m. EST on the 21st and then accelerated eastward as it strengthened. At 7 a.m. EST on the 21st, the low was already southeast of Montauk Point, New York.

Winter Weather in SALEM, NEW JERSEY
From 21-JAN-11 00:30:00 to 21-JAN-11 04:30:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in GLOUCESTER, NEW JERSEY
From 21-JAN-11 01:00:00 to 21-JAN-11 05:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in CAMDEN, NEW JERSEY
From 21-JAN-11 01:00:00 to 21-JAN-11 05:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in NORTHWESTERN BURLINGTON, NEW JERSEY
From 21-JAN-11 01:00:00 to 21-JAN-11 05:30:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in MERCER, NEW JERSEY
From 21-JAN-11 01:00:00 to 21-JAN-11 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in SOMERSET, NEW JERSEY
From 21-JAN-11 00:00:00 to 21-JAN-11 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in HUNTERDON, NEW JERSEY
From 20-JAN-11 23:00:00 to 21-JAN-11 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in MIDDLESEX, NEW JERSEY
From 21-JAN-11 00:00:00 to 21-JAN-11 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in WESTERN MONMOUTH, NEW JERSEY
From 21-JAN-11 00:00:00 to 21-JAN-11 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in MORRIS, NEW JERSEY
From 20-JAN-11 23:00:00 to 21-JAN-11 07:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in WARREN, NEW JERSEY
From 20-JAN-11 22:00:00 to 21-JAN-11 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in SUSSEX, NEW JERSEY
From 20-JAN-11 21:00:00 to 21-JAN-11 07:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter