The reason New Jersey residents may be shivering today is due to the return of the weather-maker known as the polar vortex.

(Scott Olson, Getty Images)
(Scott Olson, Getty Images)

It's also nicknamed the "arctic express." Dave Robinson, the state climatologist at Rutgers University, says it is just a blast of cold air that is normally more at home farther north that makes its way to the middle latitudes. The polar jet stream divides cold air to the north, milder air to the south.

Robinson said the polar vortex, "helped make last winter one of the coldest in the last 20."   He said the dipping jet stream in 2014 in New Jersey has meant "cool air in the summer, cold air in the winter."

"This part of the globe, namely eastern North America, is one of the coolest parts of the globe relative to normal this year," Robinson said.

We have all heard the stories about heavy snow in parts of the Midwest and dropping temperatures. In Billings, Mont., for example, the thermometer on Monday went from the 60s to the single digits in a matter of hours. Robinson said the polar vortex will not slug New Jersey that hard, however.

"So while out in the central part of the country, temperatures have been 30 degrees or more below average, by the time it makes it over here later this week and into the weekend, temperatures may be 10 degrees, perhaps 15 degrees below average," Robinson said. "But not nearly the dramatic influences it's had out in the central part of the country, or the drama we experienced here in the east several times last winter."

According to Robinson, the coming winter's outlook is "tricky."  It may not be as cold as last winter, but we may see a lot of weather changes over the course of the season.

"For a climatologist, it's fascinating, because we have influences of early season snow cover in Siberia, and what that might do to the North Atlantic oscillation," Robinson said. "We had a super typhoon that led to a huge storm in the Bering sea over the weekend that is helping to build what we call a ridge in the west, with warm air and this trough for this outbreak of polar air in the east. And then we've got an El Nino that's trying to get its act together, but not fully there yet."

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