A wintry mix of precipitation, primarily freezing rain, affected parts of southwest and nearly all of the northern half of New Jersey during the first half of the day on the 12th. Snow and sleet accumulations were only a couple of tenths of an inch and mainly over the higher terrain, while ice accumulations reached as high as around one tenth of an inch.  Because most of the wintry precipitation fell at night on the heels of an unseasonably cold air mass, untreated roadways and walkways were hazardous. Most of the main thoroughfares were treated and the relative number of accidents was low.  New Jersey Transit cross-honored tickets on rail and bus lines throughout the day. Schools in Somerset, Warren, Sussex and Morris Counties had two hour delayed openings.
Precipitation overspread the region from south to north between Midnight EST and 5 a.m. EST on the 12th. It started as a snow and sleet mixture in northwest New Jersey and as a mixture of rain, freezing rain and sleet elsewhere. Precipitation in all areas was falling mainly as freezing rain during the morning commute and then transitioned to plain rain between 9 a.m. EST and Noon EST on the 12th from south to north. The rain ended during the afternoon of the 12th.
Snow accumulations included 0.3 of an inch in Montague (Sussex County) and 0.1 of an inch in Rockaway (Morris County) and Hackettstown (Warren County).  Ice accumulations included 0.15 inches in Wantage (Sussex County), 0.10 inches in South Plainfield (Middlesex County) and 0.05 inches in Three Bridges (Hunterdon County).
The wintry mix of precipitation was caused by the combination of a low pressure system that moved northeast from the Tennessee Valley and an approaching cold front from the Great Lakes. A retreating arctic air mass left enough cold air in place for precipitation to fall as a wintry mix until it was eroded during the morning of the 12th. Precipitation ended as the cold front approached New Jersey that afternoon.

Winter Weather in HUNTERDON, NEW JERSEY
From 12-JAN-15 01:00:00 to 12-JAN-15 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in MORRIS, NEW JERSEY
From 12-JAN-15 02:00:00 to 12-JAN-15 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in WARREN, NEW JERSEY
From 12-JAN-15 02:00:00 to 12-JAN-15 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in SUSSEX, NEW JERSEY
From 12-JAN-15 03:00:00 to 12-JAN-15 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in CAMDEN, NEW JERSEY
From 12-JAN-15 00:00:00 to 12-JAN-15 09:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: State Official

Winter Weather in NORTHWESTERN BURLINGTON, NEW JERSEY
From 12-JAN-15 00:00:00 to 12-JAN-15 09:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Winter Weather in MERCER, NEW JERSEY
From 12-JAN-15 01:00:00 to 12-JAN-15 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in MIDDLESEX, NEW JERSEY
From 12-JAN-15 02:00:00 to 12-JAN-15 09:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in SOMERSET, NEW JERSEY
From 12-JAN-15 01:00:00 to 12-JAN-15 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter