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CORVALLIS - As hundreds of firefighters will attest, it's been a rather warm and dry summer. But Oregon State University's George Taylor doesn't believe the lack of precipitation will persist into the fall and winter.

In fact, he thinks we may be in for a wet few months.

Taylor, the state climatologist, released his annual fall and winter weather forecast that he bases on numerous factors, including sea surface temperatures, wind patterns, historical data, 20- and 25-year cycles, and some good old-fashioned guesswork.

"Right now, it looks like we'll have generally average temperatures during the first half of the season - from October to December - with above-normal precipitation west of the Cascades," Taylor said. "East of the Cascades, though, may still see below-average precipitation. The fire season will continue until the significant rains begin, which may not occur until mid-October.

"During the second half of the season, though, from January through March, we should see some cooler temperatures and the best chance for low-elevation snowfall," Taylor added. "Precipitation statewide is expected to be above average."

From his OSU office, Taylor works through an arduous series of steps to piece together his forecasts. He must sift through a variety of data and predictive models - some of which conflict with each other. Predictions for the tropical Pacific, for example, suggest that either a weak El Nino will develop in the next six months, or that a weak El Nino has already settled in the area and is either fading or will persist until next summer, or that we are heading into La Nina conditions.

"It does get a bit confusing," Taylor said with a laugh. "But we feel that there has been a weak, atypical El Nino during the past year and this 'quasi El Nino' has peaked and will decline in the next three to five months."

Taylor also works into his equation what he calls a "multi-decadal phase," evidence he has accumulated that suggests the Pacific Northwest goes through 20- to 25-year cycles of generally warm and dry conditions, or cool and wet conditions. Though not all of the years within that quarter-century cycle are consistent, about 75 percent are above or below average. In other words, about three-fourths of the years in a wet phase are wetter than normal.

The last wet phase, he said, went from the late 1940s until the mid-1970s.

"We probably re-entered a wet phase in the mid-1990s, and though the winter of 2000-01 was on the dry side, history tells us that we are more likely to be above average in precipitation," Taylor pointed out.

Finally, Taylor looks at a number of variables leading into the winter - including winds, sea level pressure, temperatures, and cloudless days - and compares these with past measurements. The OSU faculty member then finds years that had similar conditions and checks the weather for these "analog years."

The closest conditions to this year were found in 1957, 1965, 1970, 1974 and 1994. "And, in general, those years were slightly wetter," Taylor said.

Here is a breakdown of his forecast:

Western Oregon

• September through mid-October - Generally below-average precipitation, with just a few really wet days and warmer than average temperatures.
• Mid-October through November - Winter storms begin to arrive and precipitation becomes somewhat above average. The days will generally be cool, the nights mild.
• December through January - December will see generally average precipitation, but January will be wetter than normal. Temperatures will be cooler than average, with the best chance for low-elevation snowfalls occurring in late January or early- to mid-February.
• February through March - Precipitation will be average. Temperatures will be cooler than normal in February, but near-average in March.

Eastern Oregon

• September through mid-October - Generally below-average precipitation totals and warmer than average.
• Mid-October through November - Average precipitation and temperatures, leading to a normal opening of ski season.
• December through January - Generally average precipitation in December, but becoming wetter than normal in January. Likewise, temperatures will be seasonable until mid-January, then become cooler than average.
• February through March - Precipitation will be average in February and wetter than normal in March, with generally cooler than average temperatures through both months.

For more information on the forecast and the factors upon which it is based, visit the Oregon Climate Service website at http://www.ocs.orst.edu/.