OREGON STATE UNIVERSITY

Major storms to provide welcome relief to Pacific Northwest snowpack

02/16/2011

CORVALLIS, Ore. – Winter is back, with a vengeance. And if you’re not worried about an urban commute, it’s actually pretty good news.

A major and more traditional winter storm is moving into the Pacific Northwest today with cold temperatures and ample moisture that should provide some light snow in the Willamette Valley and give the snowpack in the Oregon Cascade Range a chance to recover from an unusually warm and dry January.

“It’s not really all that unusual to still get some good winter storms at this time of year,” said Kathie Dello, deputy director of the Oregon Climate Change Research Service at Oregon State University. “For the Cascade Range this is actually very good news, we’re at about 75 percent of normal snowpack right now and need the snow.”

The next week, Dello said, will bring a one-two punch of storms – one moving through today that could leave an inch or so of snow on the valley floor and much more in the mountains, and another coming in from Alaska about Sunday that is even better organized, with stronger winds and possibly some snow that could last longer and accumulate more.

Aside from the usual concerns about traffic accidents, commuting delays and school closures, the storm should dump a foot or more of snow on much of the southern Oregon Cascade Range and freshen up the skiing at a number of resorts that can badly use it. Mt. Bachelor has already received three feet of snow in the past three days, Dello said, and more is clearly on the way.

“Saturday might even offer a calm day between storms that would provide a good chance to ski,” she said. “There have been a lot of angry skiers in the last month.”

For a La Nina year, which typically brings cooler, wetter winters to the Pacific Northwest, this is more like it, Dello said.

“A few drier than normal weeks in January don’t change the fact we’re still in a La Nina pattern,” Dello said. “We had a very wet December, and the forecast going forward is for colder temperatures than usual and at least normal precipitation. So there’s a good chance that late winter and spring storms could bring the mountain snowpack back to normal.”

That’s important, she said, as everything from agricultural irrigation to salmon survival and stream flows in the Pacific Northwest increasingly depends on winter snowpack.

The late January anomaly, Dello said, was linked to the Arctic Oscillation being in the “negative phase” – causing warmer than normal Arctic temperatures and influencing the weather in the mid-latitudes. That helped trigger some catastrophic winter storms in the East but left Oregon under a protective upper level ridge and comparatively dry, at least later in the month, with weather patterns coming more from the south than usual.

The storms this week, National Weather Service forecasters say, are expected to hammer almost all of the West, including California. They anticipate rain, major amounts of snow in the Sierra Nevada range and Rocky Mountains, blizzards in Colorado – and some happy skiers in Oregon.