Snow forecast across 2,000 miles of U.S

© CBS News

In addition to some snow and heavy rain, bitterly cold temperatures have begun moving into parts of the U.S. and will be staying put for at least part of this week.

Snow is possible across a 2,000-mile stretch of the U.S. and meteorologist Megan Glaros of CBS station WBBM says that millions of people will deal with brutally cold weather - with wind chills as low as 50 degrees below zero for part of the northern Plains.

Here are some questions and answers about the weather:

Q: What's The Forecast?

A: The Midwest will see the tail end of a storm that could leave as many as 6 inches of snow in Chicago by early Tuesday. The National Weather Service has issued a wind chill advisory until noon Monday for the Chicago area, due to wind chills of 15 to 30 below overnight, CBS Chicago reported.

After that, Arctic temperatures like those seen in North Dakota and Minnesota will rush in. Parts of those states were expecting wind chills of between 25-50 degrees below zero through Monday morning.

It'll be a similar story in New York, where rain showers will give way to cold air. By Thursday, "New York City will be lucky if it hits 20″ for a high and could see lows near 10 degrees, according to Michael Musher with the National Weather Service's Weather Prediction Center.

In Boston, strong wind is ushering in the cold - and gusts will top out between 40-50 mph this afternoon resulting in some isolated pockets of tree/powerline damage in the region, WBZ-TV meterologist Danielle Niles reports.

Atlanta will see temperatures dip to about 15 degrees Monday and Tuesday.

In the West, a stream of Pacific moisture will drop as much as 6 inches of rain in the Seattle area and could mean substantial snowfall in the Cascades. But in San Francisco - a region that desperately needs rain - skies will be sunny.

Q: What's Causing The Temperature Drop?

A: The jet stream is dipping, meaning cold air from Canada and other northern areas is plummeting into the eastern two-thirds of the United States.

Q: Is It A Polar Vortex?

A: The phrase took on a life of its own last year, and it was blamed for everything from ice storms to the inability of the New York Giants to score touchdowns. But the National Weather Service is skittish about going anywhere near it this time around.

But the answer is yes and no. Yes, because as Musher noted, the cold air is coming from near the North Pole. But also no, because the low-pressure system isn't going to sink into the U.S. this year, just the temperatures that precede it.

Meteorologists say it's simply winter.

Q: How Can People Prepare?

A: Bundle up. For much of the country, this is the first true taste of winter weather. Musher suggests dressing properly and remembering that below-freezing temperatures can cause hypothermia.

But there don't seem to be any huge winter storms poised to strike, meaning travel in most places won't be more difficult than it usually is this time of year.

Q: What's Next?

A: Temperatures are expected to be lower than normal for several days. They could rise a bit by the end of the week. But remember: It's only January.

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