Coldest air of the season yet to freeze much of US
The coldest and most widespread blast of arctic air so far this season will spread across the majority of the United States this week.
Frigid air from the depths of the Arctic will plunge into the United States as the jet stream (a fast-river of air along which storms travel) drops southward.
The coldest days of this week will yield highs and lows generally 10-20 degrees Fahrenheit below normal from the Northwest to the Gulf and East coasts.
Departures from normal will even approach 30 degrees along the eastern slopes of the Rockies, including Billings, Montana, Casper, Wyoming, and Denver, Colorado.

The arctic blast first chilled the Northwest at the start of this week, where pockets of snow and freezing conditions made some roads slippery.
The northern Rockies and northern Plains will face multiple days of highs in the single digits and teens. Subfreezing highs will then spread to the central Plains, Great Lakes and interior Northeast.
“Afternoon high temperatures in cities like Kansas City and St. Louis will be no better than freezing late in the week, while some places in the Dakotas may have a day or two where the temperature does not even get above zero,” AccuWeather Meteorologist Brian Thompson said.
Residents will need make sure they are sufficiently bundled up before heading outdoors and make sure animals have proper shelter.
Temperatures will struggle to reach the 50-degree mark later this week along the I-10 corridor from El Paso, Texas, to Houston to New Orleans.
In the Northeast and parts of the interior Southeast, AccuWeather RealFeel® Temperatures will plunge to painful levels by the end of the week.

“This arctic air mass will mean an early cold snap for much of Florida,” Thompson said.
Temperatures in Tampa and Orlando, Florida, may struggle to get much past 60 on Friday.
Temperatures will drop below freezing across the northern part of the Florida Peninsula by early Saturday morning.
Windswept snow will fall over the Upper Midwest at midweek with a separate zone of snow likely to spread from the central Rockies, including Denver, to the interior Northeast.
As the arctic air sweeps over the warm waters of the Great Lakes, a significant lake-effect snow event will unfold.
More arctic blasts are likely to follow the next week with additional opportunities for snow possible from the central Rockies to the Northeast.
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