CORVALLIS - Typical fall weather may arrive early this year, with cooler temperatures, potentially wet conditions and a better-than-average chance for a severe wind, rain or even snow storm through December.
But the turn of the calendar to 2005 should usher in above-average temperatures, though don't put away the umbrellas too early. It may still be wet.
Oregon State University atmospheric scientist George Taylor, who serves as the state climatologist, says Oregon's fall and winter weather is influenced by a variety of factors, from sea surface temperatures in the tropical Pacific Ocean to climate cycles that researchers are just beginning to understand.
"One of the useful tools we use is to analyze analog years, in which El Nino and La Nina conditions are similar to the current year, as are other factors like surface temperatures, wind conditions and solar cycles," Taylor said. "And one thing that stands out about this coming fall and winter is that the highest analog years were characterized by some extreme weather events.
"If that holds true, we could see a major wind storm, a snow storm, high rainfall events, or maybe even a tornado," he added. "They're rare in Oregon, but they do occur."
Conditions were similar in 1971-72, Taylor said, when a flood struck northwestern Oregon in January of 1972, leading to two deaths and numerous injuries. In the spring of that year, a tornado began near Portland and crossed the Columbia River into Washington.
In 1987, another analog year, there weren't any "extreme" events, Taylor said. But a windstorm in December with 50- to 60-mile-an-hour winds caused three deaths, and an unusually late snowstorm in March of 1988 bogged down the state in a slushy mess.
"The year 1994-95 was a truly wild one for weather," Taylor said. "After a peaceful early fall, storms began in late October and continued on and off all winter. Two major storms hit within five days of each other, dousing western Oregon and causing huge snowfall in the Cascades. Winds hit 70-miles-an-hour in Tillamook and gusts up to 100-miles-an-hour were recorded at 7,000 feet on Mt. Hood.
"Then in December, a major snowstorm affected western Oregon, all the way down to the valley floors," he added.
OSU's Taylor offered the following forecast for fall and winter in Oregon:
- The Oregon Coast: October through December will have slightly below-normal temperatures and slightly above-normal precipitation. Temperatures and precipitation should be slightly above normal January through March.
- The Willamette Valley: Near-normal temperatures and slightly above-normal precipitation October through December; and slightly above-normal temperatures and precipitation January through March.
- Southwest Interior: Slightly below-normal temperatures and precipitation October through December; above-normal temperatures and slightly above-normal precipitation January through March.
- Northeast Oregon: Slightly above-normal temperatures and precipitation October through December; above-normal temperatures and slightly above-normal precipitation January through March.
- Southeast Oregon: Near-normal temperatures and precipitation October through December; above-normal temperatures and near-normal precipitation January through March.
The complete forecast is available at the Oregon Climate Service website, through OSU. It can be accessed at: http://www.ocs.oregonstate.edu/index.html.