Weakening of Polar Vortex Could Mean Unseasonably Cold Temperatures

Forecasters studying the long-range weather models are beginning to warn that a confluence of events will trigger a chain reaction that could send the polar vortex spilling down into the U.S. in the week ahead. What is a polar vortex and what does this mean for the weather pattern? Read on for all of the details.

Understanding the Specifics of a Polar Vortex

A chain reaction of events could push the polar vortex down into the U.S. later in the month, bringing frigid temperatures during a time of the year when most people expect springlike conditions. According to the National Weather Service (NWS), the polar vortex is a large area of low pressure paired with cold air that surrounds both of the poles located on either end of Earth. This area of low pressure is always present, however, it weakens during the summer months while becoming more robust during the winter season. The counter-clockwise flow of air keeps the masses of frigid air near each pole.

The polar vortex in the Northern Hemisphere typically hovers over the North Pole for most of the year. This part of the atmosphere generally remains anchored over this part of the world thanks to the presence of powerful winds.

However, shifts in the weather can cause this vortex to break apart into pieces and dive to the south toward North America, Asia, and Europe. The result of this invasion is plummeting temperatures. While not every influx of bitterly cold weather across the U.S. can be blamed on the polar vortex, the arrival of this element is guaranteed to bring the mercury down.

Various environmental factors work together to unleash the polar vortex. Specific happenings thousands of miles away can influence if the vortex remains anchored over the North Pole or if it is able to dip to the south.

Looking at the long-range forecast, meteorologists believe that a warming event next week will serve to weaken the winds that keep the polar vortex in its usual position over the North Pole. This is in contrast to a strong and stable vortex over the last few weeks that has kept the coldest temperatures away from the U.S. The expected weakening of these winds will allow the polar vortex to break down and filter from the Arctic and into North America, Europe, and Asia.

There is also the possibility that the vortex could completely collapse. This collapse is known in meteorlogical circles as sudden stratospheric warming (SSW). An SSW event was responsible for the frigid and snowy conditions that a large part of the northern U.S. experienced last month. Climate experts believe that global warming is responsible for more frequent instances of SSW over the last few decades.