An unusual weather phenomenon known as thundersnow was reported near Essex County Sunday evening, according to the National Weather Service. The rare weather event was reported around 6:17 p.m.

The National Weather Service (NWS) in Mount Holly has expanded Winter Storm Warnings to include all of southeastern Pennsylvania and portions of central New Jersey. The forecast has trended colder and snowier,

Snow will start falling between 11 a.m. and 1 p.m. in North Jersey and could begin as a brief wintery mix before turning to snow by early afternoon.

With a winter storm moving in, New Jersey is under a State of Emergency Sunday morning. The State of Emergency, declared by Gov. Phil Murphy, went into effect at 8 a.m. Sunday. The state is expecting heavy snow totaling up to 8 inches followed by extremely low temperatures.

A winter weather advisory is in effect from 1 p.m. Sunday through 1 a.m. Monday for Middlesex, Monmouth, Ocean, and Southeastern

The National Weather Service has issued a hazardous weather outlook for New York and New Jersey on Thursday. Forecasters say there is a chance of afternoon snow showers which could lead to some slippery spots during the evening commute.

High temperatures in North Jersey will be in the 20s on Monday, Jan. 20, and then drop into the teens to around 20 degrees on Tuesday and Wednesday, according to the National Weather Service. Low temperatures Monday, Tuesday and Wednesday evenings will be in the single digits.

Part of New Jersey could see a dusting of snow Thursday, but Sunday has more snow potential especially for the North Jersey region.

This will be the coldest air of the Winter season thus far, and in many cases the coldest in several years,” the National Weather Service warned.

The snow started falling in the early afternoon and will become heavier in the early evening, the National Weather Service reported.

The National Weather Service has issued winter storm warnings and winter weather advisories for 15 New Jersey counties.