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Iceman’s polar vortex has ‘gone north’ - for now

After the heavy snows, blizzards and bone-chilling cold during the first 10 days of January, you’re ready for weather prognosticators to cut you a break, right? Well, here it is — hopefully.

Last week’s milder weather across the country may continue in January, according to AccuWeather analysts. But it depends on where you are. “It depends” are the key words.

The cold air will retreat in parts of the United States, explains Senior Meteorologist Brett Anderson, but will hold on with stormy consequences in others for the rest of the month. The upcoming pattern for January will have some people in the South shedding winter coats. Others in the North will be changing up their outerwear on a daily basis.

In many parts of the nation, early January lived up to its wintry reputation. Actual temperatures plummeted to minus 40 degrees F in parts of Montana, North Dakota and Minnesota — nearly minus 50 in parts of Colorado. Yards of snow — not feet — buried the high country of the Sierra Nevada, Cascades and Rockies. At one point, snow was on the ground and freezing temperatures existed in every state except Florida.

Here’s what’s coming
Arctic air will sound the retreat in much of the southern half of the nation during the middle of the month. The main branch of the jet stream will retreat to near the border of Canada and the U.S., says Anderson. South of the jet stream, the weather is generally warm. North of the jet stream, the weather is generally cold.

There’ll still be some dips in the jet stream, allowing pockets of arctic cold air to periodically sink southward into the Upper Midwest and Northeast, he adds. Sometimes, where the boundary of cold versus mild air sets up, episodes of snow, ice and rain can occur.

One such weather battlefield will set up from the southern Plains to portions of the Midwest and the Northeast early this week. In the Southwest, a storm will manufacture cold air and unleash wintry precipitation for a time during the middle of the month.

The overall pattern first appears to be mild for much of the nation during the latter part of the month, unless the polar vortex comes into play. "There are some indications that the polar vortex may weaken enough to allow a southward discharge of arctic air before the end of the month," notes Paul Pastelok, AccuWeather’s lead long-range meteorologist. "Even in cases when there’s certainty about the weakening of the polar vortex, you never know for sure where the discharge of cold air will be directed — western versus eastern U.S."

If the polar vortex remains strong, it’ll keep the arctic air locked up in the Arctic. More places in the lower 48 states may trend warmer rather than colder late in the month.

"We believe the eastern U.S. will trend colder and stormier again toward the end of the month,” Pastelok says. “The question is: How much?" He doesn’t have an answer for that.

 

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