The snow over the weekend may well be the vanguard of another wetter-than-usual winter, thanks to a global weather pattern.
In October, the National Weather Service’s Climate Prediction Center issued a notice stating that a La Niña weather pattern is more likely than not to occur this winter in the Northern Hemisphere. If the pattern occurs, it would likely mean another cold, wet winter in Central Oregon and throughout the Pacific Northwest, according to Dennis Hull, meteorologist for the National Weather Service’s Pendleton office.
Still, while the weather pattern is an echo of the conditions that caused last year’s record-breaking winter in Central Oregon, Hull said it most likely won’t be as severe.
“It doesn’t mean you’ll have to hunker down in subzero temperatures,” he said. “It would be unlikely to be a repeat of last year.”
La Niña — along with its opposite phase, El Niño — is a tropical weather pattern that has an effect on global weather, according to the National Oceanic and Atmospheric Administration. La Niña weather patterns feature below-average sea surface temperatures in the Pacific Ocean near the equator, and tend to bring cooler-than-usual weather to the Pacific Northwest.
As of October, the National Weather Service gave a La Niña pattern a 55 to 65 percent chance of occurring. Hull added that the region bore the brunt of a similar weather pattern last year, but added that this year’s would likely be a less extreme system.
Hull added that the long-range forecast calls for temperatures that average about half a degree lower than usual across Central Oregon during the winter months, with approximately average precipitation during the same period.
In a typical winter, Bend has around 15 days where at least a half-inch of snow falls, according to Hull, and even a slight drop in average temperature would likely increase that total.
Bend received its first measurable snowfall of the season over the weekend, from a storm that brought a half-inch of snow to some low-elevation parts of Deschutes County. Hull said the first snowfall of the season came earlier than the average date for first snow, Nov. 17, though well after the earliest recorded snowfall in city history, on Sept. 24, 1934.
A snowier winter than normal would be a boon for Central Oregon’s rivers and reservoirs, according to Kyle Gorman, Central Oregon region manager for the Oregon Water Resources Department. Going into the winter, Gorman said Central Oregon’s large reservoirs are significantly more full than they were this time last year, thanks to a last year’s wet winter. As of Monday evening, Wickiup and Crane Prairie reservoirs stood at 54 and 66 percent full, respectively. Gorman said another wet winter could fill reservoirs in the region for the first time in years. Neither Crane Prairie nor Wickiup reservoirs filled completely last winter.
“I’m fairly confident we’d have full reservoirs,” he said.
Scott Oviatt, snow survey supervisor for the National Resource Conservation Service office in Portland, said a rainy autumn bodes well for snowpack development, as it prevents snow from melting as quickly in high-elevation areas and allows the soil to soak up more snowmelt.
For that reason, Gorman added that an ideal season in Central Oregon from a water conservation standpoint would feature a rainy fall followed by heavy snow in December and January, with cool spring temperatures that keep the snowpack from melting too quickly. With rain in Bend’s immediate forecast, Gorman said he’s optimistic about the region’s water levels going forward.
“My expectation is a really good winter, meaning lots of snow,” he said.
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