El Niño adds fuel to Southwestern fires

In California, Arizona and New Mexico, an underperforming weather pattern increased wildfire risk.

 

Smoke and flames from wildfires erupt behind a car on the highway near Fort McMurray, Alberta, Canada in May.
Mark Blinch/Reuters

On May 1, a devastating blaze erupted near Fort McMurray in eastern Alberta, Canada. By late May, it had engulfed more than 1.2 million acres of boreal forest — nearly double the size of Rhode Island. At the height of the fire, which was still burning at press time, more than 80,000 people were evacuated and almost 4,000 employees of Alberta’s tar-sands oil region were unable to work.

The Alberta blaze may well portend a tough fire season in parts of the West. The wildfire season is changing. Blazes are much hotter and larger than they used to be, and seasons are beginning earlier and lasting longer. The characteristics of the Fort McMurray Fire fit the trend of the mega-fires likely to hit the West as the climate warms, says Yong Liu, researcher and head of the Atmospheric Science Team of the U.S. Forest Service.

This winter’s Super El Niño has complicated the outlook. While the Pacific Ocean’s warming waters were expected to bring big storms to the southern half of the West, climatologists say the results disappointed much of the area. That left New Mexico, Arizona, central California and much of Nevada and Utah parched, exacerbating drought conditions, according to the National Interagency Fire Center (NIFC), in Boise, Idaho.

In states bypassed by the strong El Niño, the groundwork has been laid for an intense fire season, says Wally Covington, climatologist and fire expert from Northern Arizona University. Meager snowpack, dry soils and warmer temperatures will make it easier for blazes to spark and spread. According to NIFC’s May outlook, California’s near-normal snowpack (the best since 2011) has depleted rapidly, and the wildfire season is expected to be worse than usual this year, thanks to high fuel loads. Statewide, the ongoing drought has left huge stocks of desiccated timber, while in the state’s southern region, just enough El Niño precipitation fell to encourage prolific grass growth.  

That’s “both a blessing and a curse,” says Daniel Berlant, spokesman for Cal Fire. The El Niño-encouraged fuel loading has forced his agency to prepare for an earlier fire season, but “the extra rain earlier in the year has also allowed us to do prescribed burns earlier.”

Elsewhere in the West, NIFC projections show an earlier-than-normal peak for wildfire danger in New Mexico and Arizona, in May and June. But come July and August, above-average temperatures and rapidly drying fuels will bring a higher fire risk to California, Nevada and southern Idaho. The Rocky Mountain region — Colorado, Wyoming and Montana — is in relatively good shape because of deep snowpack and increased precipitation from late April through May. The Pacific Northwest should also dodge an early fire season, despite a diminished snowpack, thanks to May’s wet and cool weather.

“Super El Niños” like this one, followed by longer periods of warm La Niña conditions, are just one symptom of the larger climate shifts that many climatologists expect the arid West to see. El Niño is now transitioning to La Niña as the Pacific cools. Typically, those patterns balance each other out. But since this year’s El Niño bypassed areas expected to receive more precipitation, La Niña — which usually brings less precipitation to the region — is likely to cause the dry Southwest to become even drier.

“Once La Niña is firmly in place, we would expect to see more fires in the southern half of the Western U.S. through the fall,” Covington says. “The Southwest is not in a good position.”

Paige Blankenbuehler is an HCN editorial fellow.

version of  this article was originally published on our website, hcn.org, on May 9, 2016.