Wet monsoon storms gained strength across Arizona this week, largely bringing to a close a mild fire season.
Fires burned dangerously close to Flagstaff, Tonto Basin and several smaller communities this year, most of them sparked by lightning in early July. The period of monsoon storms that yield lightning but little rain remains the most dangerous phase of Arizona’s fire season.
The Woodbury Fire got loose and flashed across 124,000 acres, forcing the evacuation of some areas in Tonto Basin.
The Museum Fire burned just 2,000 acres on the outskirts of Flagstaff, but also caused evacuations — and continuing fears of flooding as monsoon rains hit still smoldering, denuded slopes.
Most of the rest of the fires that burned thousands of acres did more good than harm — thinning overgrown forests and clearing decades of accumulated dead and downed wood.
Every fire at least reduces the risk of a subsequent, high-intensity crown fire in the same area. However, blazes like the 745-acre Blue River Fire in the burn scar of the Wallow Fire demonstrated how much fuel remains behind even after a forest-altering crown fire.
Moreover, the Museum Fire near Flagstaff could still lead to a billion-dollar flood if heavy monsoon rains hit the steep watershed overlooking Flagstaff.
Reservoirs also had a close call this year. The 4,000-acre Hart Fire burned close to the C.C. Cragin Reservoir and the 5,000-acre Newman Fire burned almost to Flagstaff’s Lake Mary Reservoir.
Moreover, the 7,500-acre Cellar Fire near Prescott roused haunting memories of the Yarnell Hill Fire.
Fortunately, the wet winter delayed the onset of the season. But then the late-arriving monsoon left the door to disaster propped open in the first half of July.
So once again, the weather dictated the fire season.
But here’s the thing: You can’t count on the weather these days, say the experts.
Arizona will likely see much more dangerous and erratic fire seasons, thanks to changes in the monsoon coupled with an increased risk of drought and rising temperatures
One recent study concluded monsoon patterns have changed dramatically in the past 400 years, with wild times ahead.
Researchers found a way to use growth rings on coral reefs to track the shifts in the monsoon patterns over the past 400 years, according to the study published in Nature Geoscience, a peer-reviewed scientific journal.
The growth of the corals reflected the warming and cooling of the surface waters that create El Niño and La Niña conditions. That sea-surface warming affects weather all over the globe – including the intensity of the monsoon season in Arizona.
The research suggested that monsoons have grown more intense and unpredictable in recent decades, concluded the researchers from New South Wales and elsewhere. The coral growth rings closely matched the climate records from recent years, allowing the researcher to extend their models backward for centuries when climate records didn’t exist.
The research ultimately led to a tentative conclusion that monsoons will likely become more erratic as the climate gradually warms. That could mean more droughts, when the risk of megafires soars. But it could also mean more floods, which would greatly increase the potential damage from those fires.
And that’s bad news in a region that continues to struggle to deploy forest thinning and controlled burns.
It also suggests that forested communities like Payson and Pine will have to live with the threat of megafires for decades to come. Unfortunately, these communities have not adopted the kinds of building codes and brush-clearing policies that would prevent the whole town from catching fire like Paradise, Calif. did last year. Even the close approach of a wildfire could rain down so many embers that thickets of brush, overhanging eves and fire-prone roofs could spread a fire quickly through the community – even if the fire front’s a mile away.