Weathercatch: Why the threat of another Carlton Complex fire looms

Seven years ago Wednesday, lightning bolts crackled across the Methow Valley in north central Washington and struck parched landscapes.

Several weeks of intense early summer heat and very little rain had turned the scenic region of small towns, cattle ranches, orchards and dense forests into a tinderbox. On the afternoon of July 14, 2014, a dry storm system rolled across the valley and ignited four separate lightning-strike fires. Within 36 hours, hot winds whipped them into one megafire that grew fast, eventually covering a collective 104 square miles. More than 350 homes were destroyed, along with barns, campers and 366 miles of power lines. Ranchers lost 900 head of cattle and thousands of acres of grazing rangeland.

Although fire crews were assisted by the Washington National Guard, the Carlton Complex burned for five weeks. It remains the largest single wildfire in the state’s history.

Unfortunately, the threat of wildfires this summer in Washington may be even more severe than it was back then, especially east of the Cascades. The Asotin Complex Fire started last week by an early morning lightning storm in the Lewiston-Clarkston Valley underscores how primed the region is for wildfires.

It’s not a matter of whether the fires will occur, but how bad they’ll be.

Here’s why. First, much of Washington’s eastern half is coming off the driest spring since 1924. On top of that, we suffered through a prolonged and unprecedented heatwave in June when multiple locations broke records for the hottest temperatures ever recorded. What’s more, it’s mid-July and only a fraction of the normal rain amount has fallen since summer began.

Most of the region is in extreme drought, as classified by the U.S. Drought Monitor. No wonder.

As temperatures continue to run well above normal and dry conditions tighten their grip, the stage is set for another ferocious wildfire. Widespread burn restrictions, bans on fireworks and frequent “fire weather outlook” social media posts by the National Weather Service Spokane are an effort to keep another Carlton Complex Fire from happening.

Ironically, lightning strikes don’t cause most wildfires – humans do – commonly from discarded cigarettes, unattended campfires and losing control of prescribed burns or crop fires, according to a 2017 study published in the Proceedings of the National Academy of Sciences. Sparks from downed power lines and arson account for many wildfires as well, researchers concluded after analyzing 1.6 million wildfires that occurred over a 21-year period.

But despite the high number of human-ignited wildfires, the average number of acreage burned per fire is considerably less than those caused by lightning strikes, the study concluded. That’s because wildfires caused by humans tend to occur closer to population centers where firefighters can get to fairly quickly. Conversely, lightning-caused blazes often occur in remote locations where it takes longer to get noticed and gain access by firefighting crews. Also, winds that typically accompany dry lightning storms can rapidly push flames far and wide.

The National Weather Service has been issuing red flag warnings as dry lightning storms – thunder and lightning with little or no rain – roll over parts of the Inland Northwest. Whether it’s a spark from a lightning bolt or an ember from a tossed cigarette, hot temperatures, dry soils and brittle vegetation will make it easier for wildfires to start and spread this summer. Just look at how quickly the blaze took off in Asotin County last week.