Polar vortex set to unleash coldest air of season yet in US
By
Alex Sosnowski, AccuWeather senior meteorologist
Updated Jan 10, 2021 12:10 PM EDT
Bernie Rayno says it's time to get ready for a major change in the weather pattern during the second half of January.
A major shift in the weather pattern will arrive across southern Canada and the United States during the second half of winter. AccuWeather meteorologists have been monitoring the pattern in the Arctic for weeks, and they say a weakening in the polar vortex could usher in the coldest air of the season yet during the third week of January.
The polar vortex is a storm near the Arctic Circle that normally keeps cold air locked up near the North Pole.
When the polar vortex weakens, it can shift southward into one or more regions around the Northern Hemisphere. When this movement occurs, Arctic air can spill southward into Europe, Asia and/or North America.
The coldest air of the season could pack more shock value since it will follow a period of ongoing well-above-average temperatures that have been occurring in southern Canada and the northern half of the U.S. through the middle of January.
"The anticipated waves of Arctic air will have their cold tasks cut out for them at first, but once the pattern gets rolling, a major surge in heating demand is expected, and winter storms and lake-effect snow that become intertwined in the cold blasts can hit travel and daily activities hard in parts of the Midwest and East," AccuWeather Senior Meteorologist Dave Samuhel said.
First cold push to knock temperatures back to near average
The first signs of the polar vortex displacement will be later this week.
The initial cold push in the series is scheduled to sweep from the northern Plains and Midwest then the East Coast later this week.
"Even though temperatures may remain above average in the wake of the leading edge of the cold air, it will bring a 10- to 20-degree Fahrenheit drop as the front passes through," Samuhel said.
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Essentially, temperatures are forecast to average 15-25 degrees Fahrenheit above normal ahead of the cold push over the northern third of the U.S.
During the middle of January, the average high over the northern Plains is in the lower to middle 20s, while normal highs along the upper mid-Atlantic coast are in the upper 30s and in the lower 50s over the interior Southeast.
Record highs may occur in the northern Plains during the middle of the week before the colder air moves in.
"For example, a record high of 53 is forecast in Bismarck, North Dakota, on Wednesday, Jan. 13," AccuWeather Meteorologist Ryan Adamson said. The old record for the date in Bismarck is 52, and the normal high is 23.
Temperatures will be slashed back to near average once the first wave of cold air arrives.
"There is a chance that as that first front reaches the Atlantic coast it initiates a storm with snow in the Northeast and rain in the Southeast during the weekend of Jan. 16-17," Samuhel said.
More painful cold air to follow past mid-month
The first true Arctic blast related to the displacement of the polar vortex is slated for the period from Jan. 18-22.
"An Arctic cold front is expected to move through the northern Rockies and northern Plains on Jan. 18-19 then the eastern and south-central parts of the U.S. between Jan. 20 and 21," Samuhel said.
"Temperature departures in the Arctic blast can peak on a particular day between 15 and 30 degrees below normal for the Plains and Midwest and 15 and 25 degrees below normal [in the] Northeast," Samuhel explained.
Given the change from well-above-average temperatures to well-below-average temperatures over the northern third of the nation during the latter part of the month, some places may end up being 30-50 degrees lower compared to the first part of the month. Temperatures could struggle to get above zero on certain days over parts of the North Central states and may not climb past the single digits over the northern tier of the Northeast.
"However, overall, the Arctic blast is not likely to be record-setting," Samuhel said. "Temperature departures over a seven-day period will tend to be more in the realm of 5-10 degrees below average and not a constant barrage of severe cold."
As this big blast of Arctic air reaches the eastern part of the U.S., once again there is the potential for a storm to develop.
"We will be watching for a storm to develop along the upper Gulf coast and track northeastward between Jan. 18 and 20," Samuhel said.
It's possible that the storm could coincide with Inauguration Day, which will occur on Wednesday, Jan. 20. President-elect Joe Biden and Vice-President-elect Kamala Harris will still be sworn in at the U.S. Capitol but without the typical huge crowds of people who would typically be in attendance due to the coronavirus pandemic. Instead, virtual celebrations will be held, according to the Presidential Inaugural Committee.
Temperatures in the Washington, D.C., area on Inauguration Day may depend on the timing of an Arctic cold front. Temperatures may briefly surge into the 40s ahead of the front but likely plummet into the 20s in its wake.
"Several pieces will need to fall into place for this storm to materialize, but there is the potential for a high-impact storm with power outages and virtual schooling, as well as business and travel disruptions for this period with heavy snow and blizzard conditions in the northern states, heavy rain and strong thunderstorms along the Gulf Coast and Southeast with some ice in the middle," Samuhel warned.
The exact timing, track and magnitude of such a storm this far out are far from being set in stone, but major storms associated with a change in the weather pattern such as this are not uncommon.
Widespread Arctic cold is anticipated over the eastern half to two-thirds of the nation during Jan. 23-27 with well-below-average temperatures in store.
"Florida will have to watch out for potential freezes in the citrus areas and clipper storms that may bring snow from the northern Plains across the Great Lakes and into the Northeast," Samuhel said.
As the waves of Arctic air flow past the relatively unfrozen waters of the Great Lakes, significant lake-effect snow events are likely which can unload feet of snow where bands persist and lead to dangerous snow squalls with whiteout conditions that can extend a hundred miles or more to the southeast of the lakes.
Arctic cold may shift, split in early February
Forecasters say the pattern is less set in stone at the end of January and during the first 10 days or so of February. Waves of Arctic air may continue to invade areas east of the Rockies, or the cold could shift its focus over areas farther west instead.
Even if a split in the cold air develops or the Arctic air retreats, conditions may be rather stormy due to enough cold air left behind to cause snow and ice storms.
Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
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News / Winter Weather
Polar vortex set to unleash coldest air of season yet in US
By Alex Sosnowski, AccuWeather senior meteorologist
Updated Jan 10, 2021 12:10 PM EDT
Bernie Rayno says it's time to get ready for a major change in the weather pattern during the second half of January.
A major shift in the weather pattern will arrive across southern Canada and the United States during the second half of winter. AccuWeather meteorologists have been monitoring the pattern in the Arctic for weeks, and they say a weakening in the polar vortex could usher in the coldest air of the season yet during the third week of January.
The polar vortex is a storm near the Arctic Circle that normally keeps cold air locked up near the North Pole.
When the polar vortex weakens, it can shift southward into one or more regions around the Northern Hemisphere. When this movement occurs, Arctic air can spill southward into Europe, Asia and/or North America.
The coldest air of the season could pack more shock value since it will follow a period of ongoing well-above-average temperatures that have been occurring in southern Canada and the northern half of the U.S. through the middle of January.
"The anticipated waves of Arctic air will have their cold tasks cut out for them at first, but once the pattern gets rolling, a major surge in heating demand is expected, and winter storms and lake-effect snow that become intertwined in the cold blasts can hit travel and daily activities hard in parts of the Midwest and East," AccuWeather Senior Meteorologist Dave Samuhel said.
First cold push to knock temperatures back to near average
The first signs of the polar vortex displacement will be later this week.
The initial cold push in the series is scheduled to sweep from the northern Plains and Midwest then the East Coast later this week.
"Even though temperatures may remain above average in the wake of the leading edge of the cold air, it will bring a 10- to 20-degree Fahrenheit drop as the front passes through," Samuhel said.
CLICK HERE FOR THE FREE ACCUWEATHER APP
Essentially, temperatures are forecast to average 15-25 degrees Fahrenheit above normal ahead of the cold push over the northern third of the U.S.
During the middle of January, the average high over the northern Plains is in the lower to middle 20s, while normal highs along the upper mid-Atlantic coast are in the upper 30s and in the lower 50s over the interior Southeast.
Record highs may occur in the northern Plains during the middle of the week before the colder air moves in.
"For example, a record high of 53 is forecast in Bismarck, North Dakota, on Wednesday, Jan. 13," AccuWeather Meteorologist Ryan Adamson said. The old record for the date in Bismarck is 52, and the normal high is 23.
Temperatures will be slashed back to near average once the first wave of cold air arrives.
"There is a chance that as that first front reaches the Atlantic coast it initiates a storm with snow in the Northeast and rain in the Southeast during the weekend of Jan. 16-17," Samuhel said.
More painful cold air to follow past mid-month
The first true Arctic blast related to the displacement of the polar vortex is slated for the period from Jan. 18-22.
"An Arctic cold front is expected to move through the northern Rockies and northern Plains on Jan. 18-19 then the eastern and south-central parts of the U.S. between Jan. 20 and 21," Samuhel said.
Related:
"Temperature departures in the Arctic blast can peak on a particular day between 15 and 30 degrees below normal for the Plains and Midwest and 15 and 25 degrees below normal [in the] Northeast," Samuhel explained.
Given the change from well-above-average temperatures to well-below-average temperatures over the northern third of the nation during the latter part of the month, some places may end up being 30-50 degrees lower compared to the first part of the month. Temperatures could struggle to get above zero on certain days over parts of the North Central states and may not climb past the single digits over the northern tier of the Northeast.
"However, overall, the Arctic blast is not likely to be record-setting," Samuhel said. "Temperature departures over a seven-day period will tend to be more in the realm of 5-10 degrees below average and not a constant barrage of severe cold."
As this big blast of Arctic air reaches the eastern part of the U.S., once again there is the potential for a storm to develop.
"We will be watching for a storm to develop along the upper Gulf coast and track northeastward between Jan. 18 and 20," Samuhel said.
It's possible that the storm could coincide with Inauguration Day, which will occur on Wednesday, Jan. 20. President-elect Joe Biden and Vice-President-elect Kamala Harris will still be sworn in at the U.S. Capitol but without the typical huge crowds of people who would typically be in attendance due to the coronavirus pandemic. Instead, virtual celebrations will be held, according to the Presidential Inaugural Committee.
Temperatures in the Washington, D.C., area on Inauguration Day may depend on the timing of an Arctic cold front. Temperatures may briefly surge into the 40s ahead of the front but likely plummet into the 20s in its wake.
"Several pieces will need to fall into place for this storm to materialize, but there is the potential for a high-impact storm with power outages and virtual schooling, as well as business and travel disruptions for this period with heavy snow and blizzard conditions in the northern states, heavy rain and strong thunderstorms along the Gulf Coast and Southeast with some ice in the middle," Samuhel warned.
The exact timing, track and magnitude of such a storm this far out are far from being set in stone, but major storms associated with a change in the weather pattern such as this are not uncommon.
Widespread Arctic cold is anticipated over the eastern half to two-thirds of the nation during Jan. 23-27 with well-below-average temperatures in store.
"Florida will have to watch out for potential freezes in the citrus areas and clipper storms that may bring snow from the northern Plains across the Great Lakes and into the Northeast," Samuhel said.
As the waves of Arctic air flow past the relatively unfrozen waters of the Great Lakes, significant lake-effect snow events are likely which can unload feet of snow where bands persist and lead to dangerous snow squalls with whiteout conditions that can extend a hundred miles or more to the southeast of the lakes.
Arctic cold may shift, split in early February
Forecasters say the pattern is less set in stone at the end of January and during the first 10 days or so of February. Waves of Arctic air may continue to invade areas east of the Rockies, or the cold could shift its focus over areas farther west instead.
Even if a split in the cold air develops or the Arctic air retreats, conditions may be rather stormy due to enough cold air left behind to cause snow and ice storms.
Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.
Report a Typo