For the last couple of days, much of the Midwest and eastern United States has been feeling the effects of a blast of Arctic air, which has caused temperatures to plummet and wind chills to reach single or even negative digits.
The record-setting cold has been caused by a break in the polar vortex, and unfortunately, it’s not quite done yet. The latest reports indicate more Arctic air is on the way later this week.
Another blast is around the corner
According to AccuWeather, a new blast of Arctic air is forming and will roll out across the country beginning Thursday, reaching the East this weekend.
“The next big surge of Arctic air is expected to advance from the northern Plains on Thursday to the Midwest on Friday and then to the East on Saturday,” AccuWeather said. “This cold blast will follow a midweek clipper storm, which is expected to spread snow from the northern part of the Plains to the Midwest and the interior Northeast.”
More Arctic blasts could follow in the coming weeks before tapering off after the middle of the month. Those cold stretches may also be accompanied by “patches of steady snow and episodes of flurries, snow showers and heavier snow squalls.”
What is causing this period of extreme cold?
The polar vortex is “a large area of low pressure and cold air surrounding both of the Earth’s poles,” writes the National Weather Service. It is always there, but weakens during the summer and grows stronger in winter.
However, if the polar vortex stretches and expands during the winter, it causes Arctic air to be send southward with the jet stream. This explains the recent surge of cold weather across the United States.
“The polar vortex has been in a weakened and stretched state since late November,” said AccuWeather Lead Long-Range Meteorologist Paul Pastelok. “We are seeing the result as Arctic air pushes southward across the central and eastern U.S. in recent days and may continue to do so for the next couple of weeks or so in waves.”
This phenomenon occurs “fairly regularly,” per the NWS, and has caused similar large outbreaks of Arctic air in 1977, 1982, 1985, 1989 and 2014.
According to Cincinnati.com, the two most common reasons for a break in the polar vortex are “a sudden warming of the Earth’s stratosphere and a lack of strong wind activity around the pole.”
