JACKSONVILLE, Fla. – You may have seen scientists warning of a snowier (for our neighbors to the north) and colder winter thanks to disruptions in the polar vortex, but what does that mean and how will feel the change in Jacksonville?
Earlier this week, Mark Collins looked at the forecast for January, typically our coldest month. But the smart people at NOAA looked at the global condition that will drive the entire winter across North America.
Let’s start with the polar vortex -- a large area of low pressure and cold air surrounding the Earth’s North and South poles. As shown in the image from NOAA (above), the vortex refers to the counter-clockwise flow of air that helps keep the colder air close to the poles (left globe). Often during winter in the Northern Hemisphere, the polar vortex will become less stable and expand, sending cold Arctic air southward over the United States with the jet stream (right globe).
So in the most basic terms, the polar vortex is a strong stream of wind that circulates the earth just north of Canada, and when it is uninterrupted in contains the polar, arctic air north of the polar vortex over the North Pole.
If the polar vortex becomes interrupted by larger weather patterns, warming over the North Pole, etc., the stream of winds containing the cold air becomes wavy, instead of straight across from west to east.
When the polar vortex is wavy, larger areas of cold air from the North Pole dive south where the polar vortex dips. Instead of turning back north when the polar vortex turns back north, the mass of frigid air can break free and continue diving south (sometimes across the middle of the U.S. Sometimes that means mega snowstorms across the middle of the U.S, especially for the east coast of the U.S.)
So what’s up with the polar vortex right now? Scientists expect it may move from the more stable, straight-across motion to the unstable, more wavy pattern thanks to some rapid and intense warming in the upper atmosphere over the Arctic.
Meteorological scientist Doc V, tweeted about the warming over the North Pole, pointing out how rapid and intense the brief warming is.
+3.5sigma warming at 10mb over the North Pole pic.twitter.com/cnLDBRenng— Doc V (@MJVentrice) January 4, 2021
He noted a few days later in a tweet that the warming had peaked by January 7th, and cooling had begun. Some long term forecasts predict polar air diving toward Europe, leaving them freezing and snowy for the middle of the month.
For us, we’ll certainly have seen colder temperatures in the past from an unstable polar vortex allowing polar, arctic air to invade as far south as our area. By the time it makes it to us, some warming has always occurred, and the rare chances we see for a few snowflakes are usually a result of these systems. But an unstable polar vortex is not a guarantee we will see the colder air, partially because the air that escapes the vortex and dive south could miss our area completely, diving over the Atlantic or Pacific or into Europe or Russia instead.
When you look at what the long-term forecasts predict through the middle of January, we’ll see some of the polar air diving south into Texas but lifting out before it reaches us. Later in the forecast, we also see hints of that polar air moving across the middle of the country and out over the East Coast. But the freezing line only dips as far south as North Georgia, not reaching us.
Fingers crossed for a more stable polar vortex as we head into February!