Polar vortex to keep frigid pattern locked over eastern US through much of February

A wave of cold air will continue to be released into much of the eastern United States through at least the middle of the month. The ongoing pattern is likely to become stormier, with areas of ice and snow likely to spread across large swaths of the Plains, Mississippi Valley, Appalachians and Atlantic coast in the coming weeks.

Cold weather has hundreds of millions of people reaching for their thermostats and putting on layers of clothing to stay warm. The continued cold will cause heating bills to skyrocket.

Not all winter cold is caused by the polar vortex. However, the storm, which typically sits near the Arctic Circle and contains the coldest air, has shifted and weakened at times this winter, causing cold air to escape southward.

For many areas in the eastern half of the country, the Arctic outbreak that began in late January will continue into early this week and will bring the coldest/lowest temperatures of the winter.

“The subsequent flow that occurs during the first 7 to 10 days of February may not be as severe,” said Paul Pastelok, chief remote meteorologist at AccuWeather. “However, the changing effects of shrinking open water are gradually diminishing as the continued cold causes ice cover to rapidly increase in the Great Lakes.”

This means that as the Arctic air moves southward, there will be less open warm water to weaken the edge of the Arctic air, and many areas now have extensive snowpack, which further insulates the ground and helps cold air travel farther more efficiently. Both conditions can also cause temperatures to plummet during the night with light winds and clear skies.

There may be a day or two when the cold weather subsides, thanks in part to increased February sunshine, but any warming trend is likely to be short-lived.

“We are monitoring a possible polar vortex disturbance in early February that could further intensify the cold in the eastern U.S. about seven to 10 days later,” Pastelok said. “Sudden warming in the atmosphere or stratosphere tends to trigger polar vortex displacement. This displacement could add more fury to storms leading up to the middle of the month and then add more punch to the cold that follows the U.S. storm.”

Frequent outbreaks in the Arctic over the coming weeks, or essentially a continuation of the outbreak that began in mid-January, will result in monthly temperatures well below February’s historical average across much of the eastern half of the United States.

Temperature deviations of plus or minus 2 degrees Fahrenheit per month are considered average. Temperatures could be 4, 8, 10 or more degrees below average in some areas, particularly in the Midwest where the count ends on February 28th.

AccuWeather’s long-term team looks not only at conditions in North America, but also at current conditions and expected changes globally to create long-term forecasts.

“As far as the coming storm is concerned, there will be a lack of water Tuesday into Wednesday, with snow falling from parts of Missouri to Virginia,” AccuWeather senior long-range meteorologist Joe Lundberg said.

Another speedboat storm with snow is possible in the upper Midwest and Northeast a day or two later, and a second storm with ice and snow in the South by the end of the week, Lundberg added.

The larger storms Pastelok mentioned before the middle of the month will be closely studied in the coming days.

“This storm has the potential to bring ice and snow to much of the northern half of the United States from February 12 to 15, from Montana, Wyoming and Colorado to New Jersey, New York and near New England,” Lundberg explained.

In contrast to the continued cold weather across the eastern half to two-thirds of the country, temperatures will continue to be above historical averages across much of the country west of the Rockies.

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The stormy start to winter in California and the Southwest has subsided, but storms in the second week of February could break that momentum.

In the meantime, people from the plains to the Atlantic coast should keep snow shovels and ice scrapers handy. This harsh winter is not over yet.

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