ANGOLA — While Indiana may be open under the state’s Back on Track program, many Hoosiers could still be hunkered down through this season’s first winter storm during the height of the COVID-19 pandemic, which might make it less worrisome should there be travel issues with hazardous weather.
And now that we’re just weeks into fall, the long-range forecasters at AccuWeather, which supplies weather information to KPC Media Group, has released its predictions for the winter months.
Accuweather’s team of long-range forecasters, , led by Senior Meteorologist Paul Pastelok, has been analyzing global weather patterns and various weather models to project what conditions will unfold across the lower 48 United States this winter, which arrives on Dec. 21. Much of the time the setup will be driven by one key factor: La Niña.
La Niña is a phenomenon in which the surface water near the equator of the Pacific Ocean is cooler than normal, the opposite of El Niño when the water in the equatorial Pacific is in a warm phase. This change in the water temperature can have a major influence on the weather patterns all around the globe. La Niña officially developed by early September and is forecast to continue through the winter months.
The ongoing La Niña is projected to bring weather conditions similar to what meteorologists expect across the country during a typical La Niña pattern, but there may be a few subtle differences, Pastelok said.
The winter of 2019-2020 was tame, and forecasts look like the Great Lakes area will be 1-2 degrees warmer than normal.
“Another overall mild winter is possible for much of the eastern U.S.,” Pastelok said, referring how temperatures will compare to the 30-year averages in many places.
However, the entire season will not be mild all the way through. Instead, the season will be bookended by cold and snowy conditions with a pause in the wintry weather in the middle of the season.
“An early season chill is expected in the Great Lakes, Ohio Valley into the Northeast,” Pastelok said.
The first waves of chilly Arctic air will set off rounds of lake-effect snow downwind of the Great Lakes, as well as bring opportunities for snow in some of the bigger cities across the region heading into the holiday season.
After the calendar flips to 2021, Old Man Winter will eventually loosen his grip on the region.
“A big turn” is expected around the middle of the season as temperatures are predicted to rise and snowfall should decrease, Pastelok said, due in part to the strength and positioning of the polar vortex. More on that later.
But as the Northeast sees a break in the cold and snow, folks across the Great Lakes and Midwest will want to brace for some bitter spells of wintry weather.
There will be a favorable storm track mid-season for the Midwest and Great Lakes, leading to above-normal precipitation and a few heavy snowfall events, Pastelok explained.
Even with the potential for some big snow events, the season as a whole is forecast to finish with near- to- below-average snowfall for much of the Northeast and Ohio Valley. In contrast, the Upper Midwest could pick up near- to above-normal snowfall.
What about the polar vortex?
Earlier this year, the polar vortex dipped down over northeastern Canada in April, causing Easter in many parts of the U.S. to look more like Christmas. What’s in store for the dreaded weather maker this coming winter?
“We expect the polar vortex to strengthen again in the middle of the season this year,” Pastolek said, explaining that a strong polar vortex means the brutally cold Arctic air associated with it remains locked in place over the North Pole region. He said, however, that the strengthening will “probably not be as strong and won’t hold on as long as last year over the pole.”
But if the polar vortex holds strong, that could spell milder conditions for a significant stretch across parts of the Eastern Seaboard, at least for part of the season. “A strong polar vortex around the pole mid-season would lead to a possible January thaw that could linger into February for the East,” Pastelok said, expanding on what would drive the warmup for parts of the Northeast. “We are uncertain whether the vortex will play a role in the early cold shots in December, but it could have a brief role later in February or March.”