The polar vortex, a powerful upper-atmosphere phenomenon that traps cold air near the Arctic, is poised to unleash frigid conditions across the eastern United States. This comes when the vortex weakens and shifts southward, allowing cold, icy Arctic air to descend, setting temperatures close to dangerously low levels. Next week, the country’s eastern half will take the worst brunt, while in some regions temperatures could plunge up to 30 degrees below normal. That will be quite a change from the record warmth set by last year’s winter season. That has made the upcoming severe, extended cold event arrive at most parts of the nation.
According to CNN, temperatures are shaping up to be the coldest of the winter so far and will be frigid even for what’s already typically the coldest time of the year. The cold will be pervasive-more than 70% of the country’s population will experience freezing temperatures over the next week-and stick around well into the month, increasing chances for snow.
The first push of cold air will come Wednesday for the north-central US, with high temperatures in the single digits or teens expected for parts of Montana, the Dakotas, and Minnesota. Cold air will spread south and east each day for the remainder of the week and through the weekend. The West will largely miss out on any considerable cold, as has been the trend since at least the fall.
The National Oceanic and Atmospheric Administration (NOAA) has issued key messages related to climate prediction. “A significant pattern change is expected across much of the country as an Arctic Outbreak is forecast to spread from the Northern Plains to the south and east, leading to exceptionally high probabilities of below-normal temperatures expected across much of the East,” it said.
What is the Polar Vortex?
According to National Weather Service (NWS) of the United States, the polar vortex is a large area of low pressure and cold air surrounding both of the Earth’s poles. It ALWAYS exists near the poles, but weakens in summer and strengthens in winter. The term “vortex” refers to the counter-clockwise flow of air that helps keep the colder air near the Poles. Many times during winter in the northern hemisphere, the polar vortex will expand, sending cold air southward with the jet stream (see graphic above). This occurs fairly regularly during wintertime and is often associated with large outbreaks of Arctic air in the United States. The one that occurred January 2014 is similar to many other cold outbreaks that have occurred in the past, including several notable colder outbreaks in 1977, 1982, 1985 and 1989.
