A low pressure system brought mainly snow to Sussex and Warren Counties and a wintry mix of snow, sleet, freezing rain and rain to Middelsex, Morris, Somerset and Hunterdon Counties.  Snowfall in Warren and Sussex Counties averaged 3 to 5 inches.  Elsewhere (Morris County impacted the most) snowfall averaged 1 to 4 inches with up to one quarter of an inch of ice.  Precipitation started during the late evening of the 15th as snow in far northwest New Jersey and rain, sleet and snow in Middlesex, Somerset, Hunterdon and Morris Counties. As the overnight continued and temperatures dropped to around freezing, precipitation changed over to a sleet and freezing rain mixture in a larger area with snow falling during heavier precipitation bursts in most of Morris County and parts of Middlesex, Hunterdon and Somerset Counties. Just plain rain fell at lower elevations and southern sections of Middlesex, Hunterdon and Somerset Counties for the rest of the event. Toward and into the morning of the 16th, precipitation fell as freezing rain and sleet in Morris County and in higher terrain locations in Hunterdon and Somerset Counties and as snow in Warren and Sussex Counties. Precipitation ended between 7 a.m. EST and 9 a.m. EST on the 16th.  The wintry weather made the morning commute on the 16th hazardous and longer than average, especially if traveling on untreated roadways. Speeds were reduced on the New Jersey Turnpike from Middlesex County north.  There were snow removal delays on the New Jersey Turnpike from Middlesex County north also. In Middlesex County, a traffic accident closed a northbound lane of New Jersey State Route 440 in Woodbridge Township. Overall, the wintry weather caused numerous traffic accidents in west central New Jersey.
Representative snowfall included 4.6 inches in Highland Lakes (Sussex County), 4.2 inches in Wantage (Sussex County) and Blairstown (Warren County), 3.5 inches in Butler (Morris County), 3.0 inches in Allamuchy (Warren County) and Pompton Plains (Morris County), 2.0 inches in Boonton (Morris County), 1.8 inches in Hackettstown (Warren County), 0.6 inches in Pottersville (Somerset County) and 0.5 inches in Lebanon and Bethlehem (Hunterdon County).
The wintry weather was caused by a series of low pressure systems that developed along a frontal boundary in the southeastern United States on the morning of the 15th. The lows consolidated into one just east of Wilmington, North Carolina overnight on the 15th and then moved northeast. By 7 a.m. EST on the 18th, the low was located around one hundred miles east of the New Jersey coast.  The northeasterly flow around that storm track prevented warmer air at the surface (and in far northwest New Jersey aloft also) from ever moving into northwest New Jersey.

Winter Weather in SUSSEX, NEW JERSEY
From 15-JAN-13 23:00:00 to 16-JAN-13 07:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in WARREN, NEW JERSEY
From 15-JAN-13 22:00:00 to 16-JAN-13 08:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in MORRIS, NEW JERSEY
From 15-JAN-13 22:00:00 to 16-JAN-13 09:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in SOMERSET, NEW JERSEY
From 15-JAN-13 21:00:00 to 16-JAN-13 07:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in HUNTERDON, NEW JERSEY
From 15-JAN-13 21:00:00 to 16-JAN-13 07:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in MIDDLESEX, NEW JERSEY
From 15-JAN-13 21:00:00 to 16-JAN-13 06:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter