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Better enjoy that sun photo by Steve Johnson Sun shines through ice-covered teasels at dawn earlier this week in a field off of Hillcrest Road. The National Weather Service expects cold nights to continue through Tuesday, with lows dipping into the teens. State expert still says to expect a stormy winter By Peter Wong of the Mail Tribune Christmas Day is likely to be sunny and warm -- assuming that the fog burns off -- but the state climatologist says he's sticking with a long-range forecast that calls for stormy and cold weather soon. "I think we will have very cold weather, perhaps as early as a week from now," said George Taylor, who is based at Oregon State University. "We will have at least one arctic outbreak, which means snow in the Willamette Valley and perhaps the Rogue Valley. I have felt that the best chance for such an outbreak is sometime in January." His advice is to keep those snowcoats and shovels handy -- or at least the rain jackets and umbrellas -- and leave the suntan lotion in the drawer. This week's fog has forced the cancellation, diversion or delay of many flights to and from the Rogue Valley International-Medford Airport. Taylor said the stormier weather will benefit Medford and the Rogue Valley. It will break up potential air inversions that trap fog and pollutants close to the ground. Pollution levels have been within acceptable levels this week, although Thursday's reading for carbon monoxide edged up into the moderate range. Medford and the Rogue Valley have suffered from winter air pollution, notably from carbon monoxide and fine particles. Carbon monoxide is a colorless, odorless gas that results from automobile exhaust and industrial processing. It robs the body of oxygen. Particles 10 microns or less (PM-10) result primarily from dust and wood smoke. When lodged in the lungs, they make breathing more difficult. Medford has not violated the federal standard for either pollutant since 1991, but a regional plan has been adopted to keep the air clean for the next 15 years. Taylor said although cleanup efforts play a part in reducing air pollution, so does weather. "In the 1980s and early 1990s, Medford had some long, cold, damp conditions for winter air pollution that have not happened lately," he said. "In the past five years, there have been fewer winter inversions in Medford and less air pollution. It is partly a consequence of greater storm activity -- more wind to mix things up. So we see the effects of the same weather cycle in the number of air inversions that the Rogue Valley has." Taylor has based his long-range forecasts on the assumption that the Pacific Northwest has entered a cycle of wetter weather. The change is triggered by the huge area of colder-than-normal water in the Pacific Ocean known as La Nina. Its twin is the warmer-than-normal area of the Pacific known as El Nino, which Taylor and others say brought much drier weather to the Northwest between 1975 and 1994. Taylor said La Nina weather effects have occurred in four of the past five years. "To me, it is one more indication that we are in a different (climate) regime with a different weather pattern," he said. Mail Tribune Copyright � The Mail Tribune 1999, Medford, Oregon USA