A winter storm affected most of the northern half of New Jersey from  the morning of the 19th into the early part of the 20th. A wintry mix fell across the Raritan Basin and the rest of central New Jersey and precipitation fell more and more as snow across the northern third of New Jersey. Snow and sleet accumulations averaged 1 to 4 inches across the Raritan Basin and 5 to 9 inches in northwest New Jersey. Ice accretions averaged around one-quarter of an inch in the Raritan Basin.
Precipitation started on the morning of the 19th as rain and snow across northern New Jersey. As the intensity increased, precipitation changed back to snow. Only in Mercer did precipitation stay as sleet or freezing rain. As warmer air moved in aloft, precipitation changed to all freezing rain and sleet in the Raritan Basin during the afternoon of the 19th. Precipitation remained mainly snow in places farther to the north. In Middlesex, Monmouth and Mercer Counties, surface temperatures rose above freezing by late in the afternoon of the 19th and remained above freezing until the rain ended that evening. Elsewhere, temperatures remained below freezing until the event ended. Precipitation ended around Midnight EST in the Raritan Basin and during the early morning of the 20th in northwestern New Jersey.
The wintry weather led to many accidents. In Mercer County, two police officers and a prisoner were injured during a head-on collision in Hopewell Township. Vehicles were overturned on New Jersey State Route 29 in Ewing and on Interstate 295 in Lawrence and Hamilton. In Morris County, northbound Interstate 287 was backed up for three miles. The southbound side was bumper to bumper the entire length of the county. Dozens of minor accidents were reported throughout the county. In Warren County, about 30 crashes were reported, some vehicles veered off roads.
Some schools in northern New Jersey never opened. Others postponed after school sporting events and activities. Some smaller businesses closed. Non-emergency state workers were dismissed at 3 p.m. EST. In Morris County, county offices and Superior Court closed during the early afternoon. New Jersey Transit and Light Rail honored bus passes, but ridership overall was cut in half.
Specific accumulations included 9.6 inches in Wantage (Sussex County), 8.0 inches in Newton (Sussex County), 7.5 inches in Butler (Morris County), 6.6 inches in Blairstown (Warren County), 6.4 inches in Marcella (Morris County), 6.0 inches in Hackettstown (Warren County), 4.5 inches in Parsippany (Morris County), 4.0 inches in South Plainfield (Middlesex County), 3.4 inches in Stewartsville (Warren County), 3.0 inches in Bridgewater (Somerset County), 2.9 inches in New Brunswick (Middlesex County), 2.5 inches in Whitehouse (Hunterdon County) and 1.5 inches in Manalapan (Monmouth County).
The winter storm was caused by a low pressure system that moved from the central Rockies on the morning of the 18th east to Illinois on the morning of the 19th. The low pressure system reached the western Pennsylvania border early in the afternoon on the 19th. A secondary low pressure system then formed on its warm front in Delmarva and by early in the evening on the 19th became the main low pressure system. At that time it was already racing quickly east of the New Jersey coast. Of equal importance was a high pressure system that shadowed the low as it moved across the southern tier of Canada. It provided a fresh supply of cold air and assisted in having more precipitation fall as snow.

Winter Weather in MERCER, NEW JERSEY
From 19-DEC-08 08:00:00 to 19-DEC-08 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in WESTERN MONMOUTH, NEW JERSEY
From 19-DEC-08 09:00:00 to 19-DEC-08 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Weather in EASTERN MONMOUTH, NEW JERSEY
From 19-DEC-08 09:00:00 to 19-DEC-08 15:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in HUNTERDON, NEW JERSEY
From 19-DEC-08 09:00:00 to 20-DEC-08 00:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in SOMERSET, NEW JERSEY
From 19-DEC-08 09:00:00 to 20-DEC-08 00:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in MORRIS, NEW JERSEY
From 19-DEC-08 10:00:00 to 20-DEC-08 03:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in WARREN, NEW JERSEY
From 19-DEC-08 10:00:00 to 20-DEC-08 03:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in SUSSEX, NEW JERSEY
From 19-DEC-08 10:00:00 to 20-DEC-08 02:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in MIDDLESEX, NEW JERSEY
From 19-DEC-08 09:00:00 to 19-DEC-08 16:00:00 (EST-5)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter