La Niña is in town, putting the odds on a dry ski season in Southwest Colorado.
But hold your bets. La Niña, which in Spanish means “little girl,” is notoriously mischievous.
The phenomenon is a climate cycle that is powered by air rising from the Pacific Ocean into the atmosphere, where it gets swept up by the jet stream and carried across the United States.
During La Niña years, tropical surface waters in the Pacific are cool, which tends to mean drier, warmer weather for the southern part of the United States and wetter, cooler weather to the north.
The opposite happens with El Niño – “little boy” – a pattern caused by a warmer sea surface.
According to the National Weather Service, a moderate La Niña cycle began developing in the ocean in late May and has gathered strength in recent months.
Here’s why predicting La Niña is so tricky:
“Colorado is sandwiched between the area to the south where odds favor below-normal precipitation and the area to the northwest that favors above-normal precipitation,” said Jim Pringle, the warning coordination meteorologist with the Grand Junction office of the National Weather Service,
This is how we ended up with blockbuster snowfall in the winter of 2007-2008, despite it being a La Niña year.
“There can be exceptions, such as the winter of 2007-08, which was the wettest La Niña on record for western Colorado,” said Pringle.
Silverton, which averages 155 inches of snow, recorded 185 inches that winter.
He added that three of Silverton’s top 10 snowiest winters occurred during a La Niña pattern, while only two of the top 10 driest winters at Silverton occurred during a La Niña.
Recent La Niñas occurred in 1988-1989, 1995, 1999-2000, 2000-2001, and the wettest developed in mid-2007 and ended in early 2009.
That’s what keeps nearby ski areas optimistic.
“We’re kind of in an interesting position because where we’re located, we can have great years during El Niño and great years during La Niña,” said Durango Mountain Resort spokeswoman Beth Holland. “We can kind of benefit from each.”
So far, nobody’s complaining.
Durango Mountain Resort opened in late November with a respectable 23-inch base. Holland called it the area’s “best opening day ever” thanks to good conditions, extra terrain and a great turnout (1,650 skiers compared with last season’s 400).
Three new “state-of-the-art” snowcats and expanded snowmaking ensured the ski area was able to provide top-to-bottom skiing from Day 1.
At Wolf Creek, Rosanne Pitcher, vice president of marketing and sales, said the mountain opened Oct. 30 with a 14-inch midway base, not the best opening day but a decent one.
“It was a really wet snow, so it had a really good base to it,” she said.
Three storms since have delivered nearly 40 inches to Wolf Creek.
Telluride Ski Resort opened with about 15 percent of its terrain available.
“We have a soft opening,” said Tom Watkinson, spokesman for the ski area. “We opened with maybe not as much as we’d like to have open, or normally have open, but we definitely don’t do 100 percent until we get closer to Christmas week.”
Meanwhile, to the north, ski areas are rejoicing.
Steamboat Springs, Winter Park and Copper Mountain each reported one of the best openings they have had in years. With 90 inches, Steamboat Springs even broke its record for total snowfall in the month of November.
La Niña’s unpredictability makes musing over her behavior something of a local pastime.
“It’s certainly interesting to look back over years and years and create these extrapolations about what might happen,” Holland said, “but there’s no reason to think that this season couldn’t be as good as ’07-08, which was again a La Niña, and we had a great season.”
Pringle said studies indicate that jet stream patterns for La Niña tend to be unstable, making significant shifts about every three weeks. The shifts make forecasting difficult for western Colorado and eastern Utah.
“So far this winter season,” he said, “the core of the upper-level jet stream has predominately remained well north of Colorado. However, there have been occasional deviations, with the upper jet having shifted as far south as Arizona and New Mexico.”
It means anything can happen.