Autumn snowfall possible in valley.
People have barely had time to think about pulling their sweaters out of the bottom drawer and already there's talk of snow.
Yes, snow. And yes, down to valley floors still covered with autumn leaves.
It's not a sure thing yet - when is weather ever certain? - but some forecasters say it's possible that the rare series of events that have to line up just right to drop snow on the Willamette Valley may line up just right starting Sunday night. Maybe even tonight in Lane County.
What it takes is cold air, and there's a slug of Canada's finest on the heels of an arctic front forecast to roll into Western Oregon later on Sunday. At the same time, an upper-level low is expected to drop down off the coast, which could pull some of the cold air out over the ocean where it could pick up some moisture.
As that air circulates back inland and drops its moisture into the mass of cold air sitting over the valley, well, you know. It snows.
"That's a classic snow pattern for us," said Pete Parsons, a state meteorologist.
What's more certain is snow in the mountains. Much of the Cascades could get a foot or more of new snow by Tuesday, raising hopes for Thanksgiving weekend skiing.
But down in the valley there's still a lot of ifs in the forecast. If systems line up a little differently, air doesn't get pulled over the ocean far enough or long enough to gather enough moisture for low-elevation snow. Then it's just cold.
But Parsons believes chances are better than 50-50 that flakes will fall sometime between tonight and Monday night. How much is (ahem) up in the air. Might not be enough to stick, might be a dusting, might be two inches, Parsons said.
If snow is rare in the valley, it's particularly rare in November. On average, Eugene doesn't see its first snow until Dec. 31.
"For the valley it has to be juuuuust right, especially in November," Parsons said. "There's very little room for error. But the latest guidance does line it up just right."
With overnight temperatures forecast to be at about freezing, it's possible the hills around Eugene will show some white by Sunday morning, but a Saturday night snow special below that is less likely. It's also possible that after Monday's shot, a second storm could produce another round of flurries late Tuesday into Wednesday, Parsons said.
But the models used to forecast weather haven't been very consistent, so forecasters may not know until Sunday what the real chance of snow is going to be.
"At this point we can just say the threat is there, the threat is real. But is it a for-sure thing for snow? No," Parsons said Friday evening. "But right now it looks like the odds are greater than 50-50 for at least some flurries and probably 50-50 for sticking snow."
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|Title Annotation:||City/Region; Forecasters say there's a 50-50 chance that a rare series of events will create snowflakes|
|Publication:||The Register-Guard (Eugene, OR)|
|Date:||Nov 20, 2010|
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