Ice Storm and Winter Weather in New Jersey, March 12 to 13, 2001

A dry and cold dome of high pressure built into the Northeast on the 11th and 12th. Meanwhile, a low pressure system was developing over the Central States. This low moved northeast from Iowa the morning of the 12th to Lake Superior the morning of the 13th. The low's warm front also moved northeast from the Tennessee Valley the morning of the 12th to the Delmarva Peninsula the morning of the 13th. Relatively warmer air that moved northeast over this frontal boundary developed clouds and precipitation. While it was warm enough above the ground for precipitation to fall as rain, the cold air left in place by the high pressure system made it freeze on contact during the late evening of the 12th and the morning of the 13th in Sussex County and colder spots in Warren and Morris Counties. Warm air near the ground moved into the region and changed precipitation over to plain rain by around 3 a.m. EST in Morris and Warren Counties and in Sussex County by around daybreak. This took the longest over northwest parts of Sussex County where precipitation nearly ended as freezing rain. About .1 of an inch of ice accrued on exposed surfaces in Warren and Morris Counties. But totals reached as much as half an inch in the higher terrain of northwest Sussex County. Any untreated roadways or walkways were extremely hazardous.