La Niña could mean snowy winter for the northern mountains
What’s shaping up to be a La Niña weather pattern heading into winter could mean a bountiful snow year in Colorado’s northern mountains.
Or maybe not. After all, long-term weather forecasting can be a challenge, particularly when it comes to the effects of La Niña and El Niño patterns in Colorado.
If at least one thing is becoming clear, it’s that a weak La Niña pattern is beginning to set up. La Niñas occur when surface-level ocean temperatures cool in the equatorial Pacific Ocean. Their opposite, El Niños, are associated with warming temperatures there.
In Colorado, La Niñas typically result in good snow years in the northern mountains, whereas El Niños tend to benefit southern Colorado.
This winter, “If I were to describe it I would say the northern mountains would be favored for more snow than what would be normal,” said Chris Tomer, meteorologist for KDVR FOX31 and KWGN Channel 2 in Denver.
He said the I-70 corridor and the southern mountains should pretty much have a normal winter.
The National Weather Service is forecasting possible warmer-than-average temperatures in Colorado over the next three months, and Tomer said he’s expecting temperatures on the warmer side this winter for the southern part of the state.
Dennis Phillips, a meteorologist with the National Weather Service in Grand Junction, agrees that a La Niña, although not an overly strong one, is shaping up, which should mean good snow in the northern mountains.
But he noted that uncertainties involved in predicting the effects of La Niñas and El Niños, especially in Colorado. With La Niñas typically bringing more moisture to more northern states out West, and El Niños doing the same for southwestern states, “the problem with Colorado is we’re right in the middle of the country,” Phillips said.
While La Niñas typically boost snow in northern Colorado, and El Niños in southern Colorado, the actual dividing line can be dictated by where weather ridges or troughs set up in the Pacific Ocean, Phillips said.
He said what are called “atmospheric river events” also contribute to what happens in Colorado. These usher in subtropical or tropical moisture caught up in the jetstream from the central Pacific, a phenomenon that used to be referred to as the Pineapple Express, he said. While last winter was a La Niña winter, atmospheric river events contributed to the whole state having a good snow year, rather than just the northern part, he said.
Two years ago, during what was being called a “Godzilla El Niño,” Colorado’s northern mountains actually did best in terms of snowfall, Phillips noted. So the past two winters have both demonstrated that while El Niños and La Niñas are not ironclad predictors of winter moisture patterns, especially in Colorado, with other factors also playing a role.
“Still, if La Niña does get cranked up and we start to see the storm patterns set up, then yeah, I think especially the northern mountains could see some decent conditions in the early winter,” Phillips said.
Said Tomer, “If I were trying to plan out a Thanksgiving or a Christmas ski vacation, I would choose I-70 north. I would go to Steamboat, I would look at Loveland Ski Area, I would look at Winter Park, I would look at places like that.”