Cold winds are coming for Wyoming, and so is the polar vortex. When it does, it could become one of the coldest winters in recent memory.
That's the sequence of winter weather events being monitored by the NASA Climate Center.
People are interpreting data collected from the Arctic as an imminent "collapse" of the Northern Hemisphere's polar vortex, bringing the coldest winter in years to North America and Europe.
Statements like this elicit "a heavy sigh" from Cowboy State Daily meteorologist Don Day.
"Anytime I see a news story that starts with 'scientists say,' red flags immediately go up," he said. "Chill out. Take a step back before making extraordinary claims."
Nevertheless, there's some legitimacy to what's being said. Wyoming will be chilling out, and the polar vortex will have a significant impact on Wyoming's winter, depending on where you are.
"The next week to 10 days is going to make my life very difficult," Day said. "The polar vortex is going to collapse and reform, bringing cold air outbreaks and a lot of winter. The million-dollar question is how far that Arctic air will penetrate into Wyoming."
Gyrating And Wobbling
The polar vortex is a typical winter phenomenon. It's when atmospheric conditions align so that a massive surge of frigid air escapes the Arctic and descends into the Northern Hemisphere.
Day said the polar vortex does "collapse," but that shouldn't be seen as catastrophic. It's not a one-and-done occurrence.
"In some winter seasons, there will be the tendency for the polar vortex to go through different phases, which allow it to weaken and venture further south into the lower latitudes," he said. "This is one of those seasons."
Day has been calling for a colder, snowier winter for months, based on current weather patterns and historical data. The polar vortex's oscillations factored into his long-range forecast for the winter season.
However, "colder and snowier" doesn't mean the weather will stay that way every day from November to whenever winter ends. Day said Wyoming's winter tends to "gyrate" quite a bit.
"I think a lot of people's perceptions are that a cold winter stays cold all the time, 24/7, and we have days and days and days where it's cold," he said. "That really doesn't happen here."
That's why Day hesitates to embrace any forecast that "paints with a broad brush." Winter manifests differently everywhere, especially in Wyoming.
Clash Of The Titans
While the Pacific Ocean and the Arctic are the dominant forces shaping Wyoming's weather, their impact isn't universal. That's because Wyoming straddles the all-important Continental Divide.
According to Day, cold Arctic air is denser than warmer Pacific air. He likes to describe it as "molasses and maple syrup."
"It is always going to go to the lowest point of gravity, so it'll stay close to the ground," he said.
When Arctic and Pacific air collide, Wyoming becomes a "battleground" because of the complex geography of the Continental Divide. Since the Divide splits Wyoming in half, the clash between the air masses leads to different weather on either side.
"The contrast between those two air masses gets difficult," he said. "Sometimes it's a standoff, and sometimes one air mass wins out over the other. If the Arctic air isn't deep enough when it comes out of Canada, it will climb over the Divide. The Pacific air pushes moisture and air into the western side, while the eastern side gets much colder."
That's what Day anticipates happening next week. The eastern and western halves of Wyoming will experience very different winter weather.
"It can be 40 degrees with rain and snow in Jackson, while it could be near zero and snowy in Gillette," he said. "That's the contrast between these two air masses."
When the polar vortex "collapses," it will bring freezing cold to Wyoming. There could be a plethora of sub-zero days, but Day said it won't determine the course of the entire winter.
"For Wyoming, the polar vortex is episodic," he said. "The Arctic air will come in, leave, and come back again. There will be stormy weather during the transitions from one air mass to another. That's the back and forth we experience in Wyoming."
The Winter That's Coming
Day believes getting overly concerned about a polar vortex collapse is sensationalizing a well-known weather pattern. However, there's no denying that more winter is coming to Wyoming.
"Most of Wyoming's major mountain ranges got a foot of snow last night, and there's probably another one to two feet coming between now and Sunday," he said. "What we're seeing is the Arctic air retreating and giving way to the Pacific moisture."
Next week will be mild across most of Wyoming due to an influx of Pacific air and moisture. By the end of next week, another surge of Arctic air will change that dynamic once again.
The back-and-forth nature of winter weather might be frustrating or even concerning, but Day said it's a good thing in the broad strokes. When Arctic and Pacific air battle over Wyoming, the state benefits from the fallout.
"The contrast between the Pacific and Arctic patterns does favor snow," he said. "One rule of weather forecast for the mountains is that anytime you get an Arctic outbreak in the Rockies, that transition always leads to a big mountain snow event, which will eventually reach the plains, as well."
Day told Wyomingites to expect freezing outbreaks, but not relentless outbreaks, of extreme cold and winter weather in the weeks and months to come. The polar vortex is collapsing and will continue to do so, but that doesn't necessarily indicate an imminent catastrophe.
"We never have permanent winter in Wyoming," he said. "We're going to have severe cold at times, but there are going to be breaks. That's a typical winter in Wyoming."
Andrew Rossi can be reached at arossi@cowboystatedaily.com.
