A wintry mix of mainly sleet and freezing rain affected central and northern New Jersey on the 5th. Ice accretions averaged one twentieth to one quarter of an inch and any snow and sleet accumulations averaged less than one inch. Numerous accidents were reported, especially during the morning.
In southwest and east central New Jersey, precipitation started as sleet around 6 a.m. EST on the 5th, but then changed quickly to freezing rain around 7 a.m. EST and plain rain around 10 a.m. EST. Ice accretions were less than one tenth of an inch.  Across the Raritan and Passaic Basins, precipitation started as sleet around 7 a.m. EST on the 5th, changed to freezing rain around 10 a.m. EST and then to plain rain around 2 p.m. EST that afternoon. Ice accretions averaged around one tenth of an inch. In Warren and Sussex Counties, precipitation started as snow and sleet around 6 a.m. EST on the 5th and changed to freezing rain during the morning, except for parts of Sussex County where sleet persisted into the early afternoon. Precipitation changed to plain rain around 3 p.m. EST. Ice accretions averaged between one tenth and one quarter of an inch and snow and sleet accumulations were less than half an inch.
There were twenty-one major weather related incidents reported in the northern half of New Jersey because of the ice. New Jersey State Police reported fifteen crashes on state highways and roadways within an hour in Hunterdon and Warren Counties. The most serious reported accident occurred in Knowlton Township (Warren County) when a van skidded off of Interstate 80 and injured eight people. Also in Warren County on Eastbound Interstate 78 near Phillipsburg, two tractor trailers collided and one flipped over. On Westbound Interstate 80 in Allamuchy Township, an overturned vehicle blocked two lanes. The Interstate 78 eastbound bridge into New Jersey had to be temporarily closed until the road surface is treated.  In Morris County, New Jersey State Route 24 in both directions was closed in Hanover Township because of the ice. In Middlesex County, in Old Bridge Township, County Route 522 was closed because of icy conditions. In Monmouth County, New Jersey State Route 33 in Howell Township was closed in both directions because of a serious motor vehicle accident.
The wintry mix, including freezing rain, was caused by a low pressure system that moved northeast along the eastern seaboard on the 5th. The low moved from coastal North Carolina at the onset of precipitation on the early morning of the 5th, reached the Delmarva Peninsula at 1 p.m. EST on the 5th and moved through New Jersey during the late afternoon and early evening on the 5th.  There was no typical high pressure system to lock the cold air in place, but a large snow pack across the region was the de facto cold air source near the surface and prolonged the period of freezing rain than would typically be the case given the synoptic regime.

Winter Weather in GLOUCESTER, NEW JERSEY
From 05-FEB-11 06:00:00 to 05-FEB-11 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in NORTHWESTERN BURLINGTON, NEW JERSEY
From 05-FEB-11 06:00:00 to 05-FEB-11 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in CAMDEN, NEW JERSEY
From 05-FEB-11 06:00:00 to 05-FEB-11 10:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in SOUTHEASTERN BURLINGTON, NEW JERSEY
From 05-FEB-11 06:00:00 to 05-FEB-11 08:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in WESTERN OCEAN, NEW JERSEY
From 05-FEB-11 06:00:00 to 05-FEB-11 09:30:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in MIDDLESEX, NEW JERSEY
From 05-FEB-11 07:00:00 to 05-FEB-11 12:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in SOMERSET, NEW JERSEY
From 05-FEB-11 07:00:00 to 05-FEB-11 14:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in HUNTERDON, NEW JERSEY
From 05-FEB-11 07:00:00 to 05-FEB-11 14:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in MORRIS, NEW JERSEY
From 05-FEB-11 05:00:00 to 05-FEB-11 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in SUSSEX, NEW JERSEY
From 05-FEB-11 05:00:00 to 05-FEB-11 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in MERCER, NEW JERSEY
From 05-FEB-11 06:00:00 to 05-FEB-11 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in WARREN, NEW JERSEY
From 05-FEB-11 05:00:00 to 05-FEB-11 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Winter Weather in WESTERN MONMOUTH, NEW JERSEY
From 05-FEB-11 07:00:00 to 05-FEB-11 11:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet