As we approach late autumn and early winter, some unusual phenomena seem to be brewing in the stratosphere, with meteorologists suggesting that this could alter the course of winter forecasts.
Weather models indicate that there are some unusual developments in the stratosphere that could lead to a sudden warming, pushing the polar vortex further south than usual, potentially impacting weather patterns in the United States. At the same time, the La Niña phenomenon is also a significant weather influencing factor. The question of whether the polar vortex or La Niña will dominate winter weather in the United States has drawn the attention of meteorologists.
Judah Cohen, a scientist and climatologist at the Massachusetts Institute of Technology, stated in an email to USA TODAY that the atmosphere is at a “critical moment” and the changes occurring in November could serve as a “fork in the road” for the entire winter.
The weather models suggest that a sudden stratospheric warming may occur, resulting in a cooling effect on the Earth’s surface. Experts believe that if this “sudden stratospheric warming” event does materialize, cold and snow could quickly sweep across much of the United States.
Cohen, the climatologist, explained that these developments will determine how the often misunderstood polar vortex, also known as the Arctic vortex, will affect U.S. weather, and how the La Niña weather pattern will guide the influx of cold air from the north.
He described a series of potential events that could rapidly unfold: a “sudden stratospheric warming” (SSW) over the Arctic could push cold air southward towards the United States. Such warming would lead to the polar vortex being displaced further south than usual.
He further added that if a sudden stratospheric warming indeed occurs, this would be the first such event in November since satellites began recording data with precision.
“That would be an extraordinary, perhaps a unique event,” he said.
If Cohen’s predictions come true, the polar vortex will have a significant impact on the upcoming weather – but as previously mentioned by meteorologists, the La Niña phenomenon also plays a crucial role.
Cohen believes that the relationship between the two is complex – there is no clear winner in terms of which weather pattern will dominate winter. Instead, the weather pattern of the polar vortex has a greater impact on determining how cold it will be, while La Niña’s role lies in directing the movement of this cold air.
Overall, Cohen expressed that “the activity of the polar vortex has a greater impact on whether the United States will experience cold weather.”
He stated that if the stratospheric warming event strongly affects the jet stream and the U.S. weather, it implies that from a certain time in December, there will be an extended period of cold and/or snowy weather. This impact could also extend into early January next year, significantly increasing the chances of colder winter weather in the United States.
“If the interaction between the polar vortex and the jet stream is weak or interrupted in the foreseeable future, then the U.S. as a whole may experience mild weather. I believe this would greatly increase the likelihood of overall mild or quite mild winter weather in the United States,” he said.
Meanwhile, federal forecasters at the Climate Prediction Center stated on Thursday (November 13) that the climate “troublemaker” La Niña will be the primary driving factor behind winter weather in the United States.
Jon Gottschalck, the head of the Forecast Operations Branch at the Climate Prediction Center, told USA TODAY that the impact of the La Niña phenomenon may be most significant during the winter, hence it plays a crucial role in the winter outlook recently released by the Climate Prediction Center.