La Niña = Big snow
From the Winter 2017 Issue
If the climate is warming, then how do you explain big, snowy winters?
Katherine Rowden and her colleagues at the National Weather Service in Spokane have heard the question a hundred times. Their answer is simple: “The weather and the climate are two different things.”
And so while everyone from NASA scientists to avalanche experts point to the effects of global warming on North Idaho’s long-term snowpack trends, the National Weather Service says there’s a 50-50 chance that this winter will be colder and snowier than usual.
Each eventuality can be true without contradicting the other, said Rowden, a hydrologist at the NWS.
It’s simply a matter of time. The climate is a measure of how Earth’s atmosphere “behaves” over relatively long periods of time – 30 years or more. Weather gauges short-term (minutes to months) conditions: temperature, precipitation, humidity, cloud cover, visibility, wind and atmospheric pressure.
And so the short-term weather models say the winter of 2016-2017 is “slightly favored” for a La Niña pattern of airflow and precipitation. That’s good news for Sandpoint, Schweitzer Mountain and the Cabinet and Selkirk mountains.
Chris Tomer, a meteorologist at OnTheSnow.com, explains how it works.
La Niña is the name folks in Tomer’s line of work give to the weather events produced when water in the South Pacific cools down more than usual. That cooler water begets cooler air, which pushes the jet stream to the north.
And since the jet stream is the channel of strong winds that guides storm systems around the globe, its position determines where the heaviest snow falls each winter, Tomer said.
He believes this winter’s La Niña will guide the heaviest snowfalls to the Pacific Northwest, Intermountain West, Great Lakes and possibly parts of the Northeast.
In Tomer’s forecast, Schweitzer Mountain and Sun Valley could be among the biggest winners, with 125 percent of average snowfall. Only Mount Hood, Mount Baker and Mount Rainier in Washington fare better, at 130 percent of average.
“La Niña years can be good snow years,” confirmed Rowden, at the National Weather Service. “And I’m all for one of those.”