A wintry mix of precipitation affected northwest New Jersey throughout the day on the 28th and west central New Jersey during the morning of the 28th.  The effects of the wintry mix increased markedly farther northwest in the state and half minimal impact in the southern half of the state. Snowfall average around one inch in the northwest part of the state and less than half an inch elsewhere. Of greater impact, ice accumulations averaged one to two tenths in the northwest part of the state, around a trace in the west central part of the state and little if any in the southern and east central parts of the state.  While snowfall amounts were light, any freezing rain froze quickly as this precipitation followed several days of unseasonably cold weather. Untreated roadways and walkways were hazardous.
Steady precipitation started across the state as snow mainly between 7 a.m. and 9 a.m. EST on the 28th.  As warmer air moved in aloft, the snow changed to sleet for a brief period and then rain in the southern and east central parts of the state between 930 a.m. EST and 1030 a.m. EST on the 28th.  In the west central part of the state, the change to sleet and freezing rain occurred during the late morning on the 28th and then the change to plain rain occurred around Noon EST on the 28th.  In the northwest part of the state, the snow changed to sleet around 11 a.m. EST on the 28th and then freezing rain by the early afternoon on the 28th. Precipitation continued as freezing rain northwest and rain central and south until it ended later that afternoon on the 28th.
Snowfall amounts included 1.5 inches in Phillipsburg (Warren County), 1.3 inches in Allamuchy (Warren County), 1.2 inches in Byram (Hunterdon County), 1.0 inch in Mine Hill (Morris County), 0.8 inches in Wantage (Sussex County), 0.5 inches in Landing (Morris County), Hardyston (Sussex County) and Hackettstown (Warren County), 0.4 inches in Red Bank (Monmouth County) and Pennsville (Salem County), 0.3 inches in Ewing (Mercer County),  Point Pleasant (Ocean County), Hillsborough (Somerset County), North Brunswick (Middlesex County), Clinton (Hunterdon County), Skillman (Somerset County) and at the Atlantic City International Airport and 0.2 inches in Westampton (Burlington County) and National Park (Gloucester County).  Ice accumulations included 0.15 inches in Sussex (Sussex County).
The wintry weather was caused by a low pressure system and its associated warm front that emerged from the central Rockies on the morning of the 27th, reached Iowa on the evening of the 27th,  southeast Wisconsin on the morning of the 28th and southwest Ontario province on the evening of the 28th. Precipitation ended as its associated warm front neared New Jersey and a secondary low pressure system formed east of the state.

Winter Weather in MERCER, NEW JERSEY
From 28-JAN-13 08:00:00 to 28-JAN-13 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in HUNTERDON, NEW JERSEY
From 28-JAN-13 07:00:00 to 28-JAN-13 13:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in SOMERSET, NEW JERSEY
From 28-JAN-13 08:00:00 to 28-JAN-13 13:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in WARREN, NEW JERSEY
From 28-JAN-13 07:00:00 to 28-JAN-13 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in SUSSEX, NEW JERSEY
From 28-JAN-13 07:00:00 to 28-JAN-13 17:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in MORRIS, NEW JERSEY
From 28-JAN-13 08:00:00 to 28-JAN-13 17:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter