Polar vortex to usher in much colder air to central and eastern US into end of January
Colder air is returning to the central and eastern U.S. as the polar vortex becomes more active, bringing fluctuating temperatures, periodic snow and the potential for a deeper cold blast late this month.
AccuWeather’s Anna Azallion warns round after round of Arctic air and snow will grip much of the Midwest and Northeast for the remainder of the month of January.
Colder air is becoming re-established in the central and eastern United States after a recent warmup. Over the next 10-14 days, the polar vortex will be active, with the possibility of cold air dominating the weather pattern through the end of the month and into early February.
"Over the next couple of weeks, the jet stream will develop a large buckle with a northward bulge along the Pacific Coast and a southward dip centered on the Great Lakes," AccuWeather Lead Long-Range Meteorologist Paul Pastelok said. "This setup stretches the polar vortex, sending persistent warmth near the bulge and repeated shots of cold air through the dip."
For example, temperatures in Chicago are expected to swing from near average to 10-20 degrees below average over the next one to two weeks. The average high in Chicago is near 32 degrees Fahrenheit. In New York City, temperatures will range from near the historical average in the upper 30s to 5-10 degrees below during the same period.
Because of the large, rounded shape of the jet stream dip, it will be difficult for storms in the South to rapidly strengthen along the Atlantic coast and become major snowstorms. Instead, most storms will stay weak, move quickly and exit out to sea through much of next week. However, any fluctuation, even brief, could be enough to allow a southern storm to track farther north and hug the Atlantic coast. AccuWeather meteorologists continue to monitor a brief snow event along the Atlantic coast from Saturday night to Sunday night.
The waves of cold will bring clipper systems and rounds of lake-effect snow, snow squalls and flurries from the Midwest to the Northeast.
"Very cold air is building back again in western and central Canada, but it will take some time," Pastelok explained. "As this happens, people in the Central and Eastern states will experience typical winter weather and colder conditions than during the past week or two."
Later this month and into early February, there is the potential for a more significant shift in the polar vortex.
"There are some indicators that point toward unusual warmth poking all the way into northern Alaska," AccuWeather Long-Range Meteorologist Alex Duffus said. "That setup could play a role in a major shift of the polar vortex."
Depending on snow cover across southern Canada, the Midwest and the interior Northeast, along with ice cover on the Great Lakes, this has the potential to bring some of the coldest air of the winter.
In December, while the lakes were mostly ice-free, there was extensive snow cover across the north-central and interior Northeast. On the coldest December days, temperatures in the Midwest were 20-30 degrees below average, and in the Northeast, temperatures were 10-20 degrees below average. Snow and ice cover tend to act as an insulator and lock out the warming effects of the ground and water.
One way a major storm could develop would be if a roadblock in the atmosphere forms near Greenland, which can trap storms along the Atlantic coast and raise the risk of heavy snow.
There are signs a large storm could develop late next week, but AccuWeather's long-range team says it is still too early to determine specific details of the potential storm.
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