WINTER FORECAST CALLS FOR GLOVES, HAT AND A SHOVEL.
For the record, it is not beginning to look a lot like Christmas.
But with Labor Day on our doorstep, there are those who already hear the faint sound of winter knocking. One of them is Oregon State University climatologist George Taylor, who says the odds are better than usual that sometime this winter Frosty the Snowman will deliver that knock.
Taylor has just issued his annual fall and winter forecast, which predicts a season a bit on the cooler and wetter side of average. And although snow in Western Oregon is notoriously difficult to predict, Taylor is going out on a limb.
"I think we have a greater than 50-50 chance," he said. "If history repeats itself, then we will more likely than not get some snow at low elevations this winter."
Taylor brings up history because it plays a fairly big role in his annual forecast. In addition to looking at the usual array of climate indicators - everything from surface temperatures in the Pacific Ocean to hurricanes in the Atlantic - he also scans weather history for years when conditions going into the cold season are most like the current year.
These are known as "analog years," and in three of this year's four analog years the Willamette Valley got a coating of snow. In two of the years, in fact, it was more like a down blanket.
Those were the winters of 1970-71 and 1988-89, when parts of the valley got not just a dusting but a dumping of snow. The other two analog years are 1952-53 and 1953-54, with the latter also featuring a snowy interlude.
But Taylor is the first to remind us that if just predicting the general trend of weather is dicey, predicting snow in this part of the country borders on prophecy. He's more confident in the rest of his winter forecast, which calls for somewhat cooler than normal temperatures and a bit more rain than usual for the sponge that is Western Oregon.
That's largely driven by what's shaping up to be no more than a moderate La Nina event, where waters in the tropical Pacific run on the cool side of average. Unlike the warm-water El Nino, a La Nina tends to bring wetter, stormier weather to the Pacific Northwest.
And a relatively weak La Nina could mean particularly rainy weather, Taylor said.
"Historically, moderate La Ninas tend to be pretty wet, and strong La Ninas tend to be really cold," he said. "I will not be shocked nor surprised if we get at least one big rainfall event with possibly some local flooding."
This year's prediction calls for winter to come on gradually, with conditions in October tending toward warmer and drier than usual. That starts to turn around in November, with December and January turning wet and February and March cold.
It's a recipe that runs in reverse of last winter, which had pretty much all the excitement packed into the first half of the season and mostly mundane weather after that. "I think this year it's going to be turned around the other way," Taylor said. "It's the second half that looks exciting this year."
And snow? Skiers should see good conditions in the Cascades, although Taylor said the season might be slow to arrive. Valley dwellers will just have to wait and see.
"Extremes are always difficult to predict," he said. "And snow is an extreme event here."
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|Publication:||The Register-Guard (Eugene, OR)|
|Date:||Aug 31, 2007|
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