Wildfire occurrence is down across the Southwest this year asa result of increased rainfall

Wildfire occurrence is down across the Southwest this year asa result of increased rainfall.

Wet spring brings fewer wildfires to Southwest

The number of wildfire events have been way down so far this year, a development fire officials say is a welcome break from four years of elevated fire activity.

With the Memorial Day weekend behind us and the peak months of summer just ahead, national and state firefighting agencies, including the U.S. Forest Service, would have, in most any other year, been active fighting wildfires across the Southwest.

But thanks to El Niño and the heavy rains that have fallen across the region as a result, the number of wildfire events have been way down so far this year, a development fire officials say is a welcome break from four years of elevated fire activity.

While El Niño, or Southern Oscillation events, can be the cause of heightened fire events, especially in the Northwest, the Southwest, mountainous West and Far West (including California) can actually experience a reduced number of fire events because of the frequent influx of moisture propelled by such weather developments. 

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According to the National Interagency Fire Center (NIFC), instances of major wildfires in 2015 are off to a slow start. Over a ten-year period from 2005 through 2014, an average of 27,329 fire events were realized nationally during the first five months of each year, causing an average 1.1 million acres of burned landscape.

Most of these fires occur from the U.S. Southwest to the Far West Coast. But because of exceptional rain showers and elevated moisture in the atmosphere, the first five months of 2015 have seen fewer wildfire events nationwide, less than 22,000 fires affecting just over 344,000 acres.

That represents about a 20 percent drop in the number of wildfires in the U.S. and a greatly reduced number of acres burned, only about 30 percent of the average for the same period of time. For the southwestern states, an even greater reduction in the number of wildfires occurred this year compared to the 10-year average.

Kerry Jones, a meteorologist for the National Weather Service in Albuquerque, says a cooler spring, an early snowmelt in the mountains that has helped to keep ground conditions wet, and regular rain events generated from the current El Niño system have combined to help control wildfire so far this year.

Jones says the Southwest has benefited from a Pacific jet stream from which warmer equatorial surface waters feed storm systems under El Niño conditions. While the ENSO event was slow forming, forecasters say indications point to El Niño continuing to affect weather in the Southwest. While sporadic but locally substantial rains across the region began falling in early winter, by the time March rolled around, heavier and more frequent storms battered the region and continue to do so as June arrives.

Precipitation limits wildfire

NWS forecasters say during normal years harsh winds and unproductive thunderstorms spark forest fires across the region, but this year’s precipitation has helped to keep moisture in vegetation and has added moisture to the environment with humidity or lingering cool, wet conditions.

Whatever the science behind it, Jones and fire officials at the National Forest Service say millions of dollars have been saved this year as a result of fewer fires. And if frequent rain events continue across the Southwest as forecast, the hope is the trend for fewer wildfires will continue.

While that outlook sounds promising, a down side exists with a wet year that can enhance or subdue the wildfire season. While rainfall across the region can be enhanced by El Niño, and suppressed by La Niña, the bigger picture requires researchers to look at the multiyear outlook following a wet spring and summer season. Fire analysts warn a wet year reduces fires while increasing vegetation growth, and this increased vegetation dries out in subsequent dry years, increasing fuel for wildfires. Grass and brush that grow in the rainy cool season could dry out later this summer, providing additional fuel for wildfires.

In addition to El Niño bringing more rain to the Southwest in recent months, weather specialists warn such Southern Oscillation events may influence storm development during the tropical season. While El Niño tends to boost tropical activity in the Pacific Ocean, it clamps down on storm formation in the tropical Atlantic. In fact, just days ahead of the release of the official NOAA Atlantic Basin hurricane forecast, at least one major forecaster has already hinted that this could be an extremely slow year for Atlantic storms.

But stepped up tropical systems in the Pacific off the coast of Mexico could still funnel heavy moisture and rainfall across the Southwest this summer if winds aloft direct rain bands into the tropical jet stream. That could mean more rain and fewer wildfires in the weeks ahead.

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