The two small fires that flared up last month in the Coconino National Forest in northern Arizona were fairly unremarkable in size or intensity. Fire crews responded quickly, and the burns were controlled without incident or loss of property.
What was remarkable about the fires was their timing. "I remember, as a boy, the fire season in this in this part of the world would arrive in May or June," said R. Scott Anderson, professor of environmental and quaternary sciences at Northern Arizona University. "To have fires coming at the end of March -- that's pretty unusual."
After a winter of tough droughts and well-below-average rainfall, the western United States -- and the Southwest, in particular -- is heading into what forest managers say could be a very difficult and expensive fire season. Despite some late winter rain, drought conditions remain severe to exceptional for most of the West, with the most extreme conditions found in California and Nevada, according to the latest monthly outlook issued by the National Interagency Fire Center (NIFC).
The lack of moisture comes as a one-two punch for vegetation in affected regions. Dry conditions stress plants, limiting their growth and "greening" in a season when they should be absorbing as much moisture as possible. That, in turn, makes vegetation more vulnerable to fire and insect outbreaks.
Freeway commuters near San Diego got a taste of wildfires in 2008. This year, there could be more. Photo courtesy of Flickr. Photo courtesy of Flickr.
Compounding that, low snowpack levels in the Sierra Nevada and other Southwestern mountain ranges mean less gradual summer runoff, drier soils and more fire-prone conditions.
The combination of these factors means longer fire seasons on both ends of the summer. California, the Great Basin and the Southwest are all moving toward an accelerated fire season, the NIFC report said. Earlier-than-normal outbreaks are expected for parts of Alaska, as well, it said.
A paradigm shift?
It's a pattern that's becoming increasingly common as the West warms and dries, according to Anderson.
"If you look at the last century, we've had a number of drought events that have been significant for this region," he said. "There was the great drought of the 1930s, and another drought in the 1950s that had an effect on the character of lower elevation forests. But I would say, in general, the current period of drought" -- which began in the late 1990s -- "is the worst the Southwest has seen since the beginning of the 20th century."
The effects on fire behavior have been particularly pronounced, he said. "The big Southwestern fires of the past 20 years have all happened since 2000," he said, noting that the problem stemmed from a combination of overgrown forests and abnormally dry conditions.
The Forest Service has issued similar warnings, predicting that the geographic footprint of fires in the United States could double by 2050.
While parts of the country, such as the Northeast, may become cooler and wetter in the future, the increased fire activity will disproportionately affect arid regions in the West.
Conditions better elsewhere in the country
The season's silver lining runs through northern Colorado, Montana, Wyoming and the Dakotas, where heavy snowfall has helped alleviate formerly dry conditions. "Mountain snowpack reached near record levels for snow-to-water equivalency in many basins with the greatest amounts observed along the Continental Divide and across southwestern Montana," the NIFC report said.
Parts of Montana have seen between 400 and 600 percent of normal precipitation this winter.
Cooler-than-normal temperatures could continue into the summer, which could help to dampen conditions for the rest of the summer, even after more normal levels of precipitation and aridity have returned.
While winter precipitation has left higher elevation regions of Colorado with healthy snowpack levels, the state -- as well as its neighbors Kansas and Nebraska -- is still emerging from long-term severe drought, meaning parts of the states will be moisture-stressed for some time to come.
Elsewhere in the country, conditions are more or less normal. Fuel conditions and the start of the wildfire season are on track to follow historical trends, NIFC said.
Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. 202-628-6500.
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