Scientists forecast alarming fire threat.

Byline: Bill Bishop The Register-Guard

Doubts about the length of Oregon's current dry spell and the looming danger of wildfire are rapidly evaporating among scientists who combine global climate models with vegetation databases to predict wildfire risk.

The scientists predict harsh drought conditions in the Northwest and severe fire danger for parts of Oregon.

Their forecast, issued Tuesday, is more than an educated guess. Their climate and fire-prediction models have proved to be reliable when applied to historic data, said Ronald Neilson, a bioclimatologist with the U.S. Forest Service and professor of botany at Oregon State University.

Unlike short-term weather forecasts, climate models are built on surface temperatures of all the world's oceans - the very engines that drive global climate conditions, Neilson said. And vegetation data gathered for decades to study why plants grow where they do enables scientists to project wildfire risk in specific areas.

By using the two models with data stretching back to 1895, the system closely reflects what actually happened and ought to be a fairly accurate projection for the near future, said Neilson, who is part of a team from the Forest Service and OSU that developed the forecasting system as an outgrowth of their studies on global warming.

For example, the system accurately predicted last year's fire season would be mild, even though it started with a long, ominous dry spell.

Their prediction for this summer is less kind.

"We project that the drought severity the Northwestern states are now experiencing will only get worse in coming months, and will reach levels that were generally seen during the Dust Bowl of the 1930s," Neilson said.

"We use five different climate models as the underlying basis for our projections, and they are all showing the same thing.

"It is going to become extremely dry in many parts of the Pacific Northwest and northern Rocky Mountain states, and the fire risk is going to be significantly higher than normal. There is nothing to indicate a wet spring."

Conditions are similar to 2001, the fourth-driest year on record and the most recent dry year.

In a one-week period in August 2001, wildfires were burning across a half-million acres in 10 Western states. More than 21,000 firefighters were working on 42 major fires - about half of them on major Oregon fires covering 270,000 acres.

In that period, more than 2,200 new fires were sparked by lightning strikes in parched forests and grasslands, according to news accounts from then.

Based on vegetation conditions, this year's wildfire hot spots are likely to be Northeastern Oregon and southeastern Washington. However, the scientists also predict "more isolated but severe fire potential in forests near Eugene, Roseburg, Bend and the Portland area."

While the models take into account existing conditions, some factors are not accounted for, Neilson noted.

"The trickiest part is we don't yet know how to do (predictions of) lightning and people lighting matches," he said.

Severe drought does not automatically translate into major fires, said James Lenihan, a fire and ecosystem modeler for the Forest Service and a colleague of Neilson.

"It takes ignition sources such as lightning storms to trigger multiple fires, and that doesn't always happen," Lenihan said. "But those events are fairly common and, because of that, fires will often occur if vegetation, moisture and climatic conditions are right - which it appears they will be this year."

CLIMATE FORECAST

For fire probability, fire area maps, forecasting and past data, go on the Web to www.fs.fed.us/pnw/corvallis/mdr/mapss/