CORVALLIS, Ore. – The newest forecasts of summer drought and fire by researchers at Oregon State University and the U.S.D.A. Forest Service suggest the West is in for a fairly severe fire season, brought on by widespread drought conditions and huge fuel buildups in western forests and rangelands.
By contrast, most of the nation east of the Rocky Mountains should have few or no fire concerns in coming months, the study indicates, even though there may be some continued drought in various places and some fires are already under way in Florida and Georgia.
“Fire is a combination not just of immediate drought stress but also of recent weather years and fuel loads,” said Ronald Neilson, a professor of botany at OSU, ecologist with the Forest Service and one of the nation’s leading experts on the interaction between climate and vegetation.
“There are pockets of drought all over the country, but the coming fire season looks like it could be focused in the West and a very nasty one, worse than normal,” Neilson said. “There could be some fairly large fires.”
Among the areas of greatest fire risk, the latest analysis shows, are much of northern California; southern Arizona and New Mexico; and the Great Basin, especially some hot spots in eastern Idaho and southwestern Wyoming. In the Pacific Northwest, portions of southern Oregon, northeastern Oregon and eastern Washington are projected to have some significant fires. Most of the Cascade Range and Coast Range face lesser risk this year.
Drought predictions are more diverse, showing drought of varying severity in western Oregon and Washington, most of California and the Southwest, Florida, Wyoming, the Northern Plains, and northern Wisconsin and Minnesota. Wetter than normal conditions are expected in the Ohio Valley, Maine, western New York and one area that’s traditionally very dry – the Llano Estacado of West Texas and New Mexico.
Various computer models and programs were used to produce these projections, and there was a pretty strong agreement among different models, the scientists said. This suggests that the level of confidence in the predictions should be reasonably high.
According to Neilson, a moderate El Nino condition – referring to circulation patterns in the tropical Pacific Ocean that affect weather all over the world – seems to be shifting towards a weak La Nina event. Ordinarily, that would produce conditions a little dryer in the Southwest and wetter in the Northwest – but so far, Neilson said, some of the drought conditions in parts of Oregon, Washington and Northern California appear to be very persistent.
Beyond current weather, fire concerns in the West are largely a reflection of recent history, Neilson said.
“We’ve heard a lot of discussion and talk about thinning of western forests to reduce drought stress and improve forest health, but in actual practice that hasn’t occurred on a broad scale,” he said. “Combined with fire suppression or exclusion and a fairly moderate climate in the past 50 years, that has led to extreme fuel buildups and excess biomass in many western forests. There’s a lot of material out there ready to burn.”
The Great Basin also faces concerns, researchers say, based on an invasive species – cheatgrass. This type of grass has often displaced native bunchgrass that tends to stay alive and green longer during the summer, lessening fire risk. Cheatgrass is an annual that dies off during the summer, leading to bigger rangeland fires that also tend to take out sagebrush and the ecosystem associated with it.