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Lightning is the No. 1 cause of wildfire ignitions in Southwest Colorado. But when a lightning bolt strikes in the vast expanse of the San Juan Mountains, how do fire agencies know how to track it down?

The answer includes invisible electromagnetic waves, exploding trees and drones. From the initial strike out of the clouds to wildland firefighting crews on the ground, tracking lightning is complex; however, the process has become more efficient in the last decade because of new technologies. Agencies anticipate an even more efficient future as they keep one eye on the sky and the other on the complex fire environment around them.

“It’s great to be able to wake up in the morning with a cup of coffee and look at the lightning map,” said Jay Godson, district fire management officer for the U.S. Forest Service Pagosa Ranger District.

Lightning caused 83% of wildfire ignitions in the San Juan National Forest between 1996 and 2016. Most, about 40%, occur in July, according to the 2017 San Juan National Forest Fire Danger Operating Plan.

Typically, lightning strikes last for only tenths of millionths of a second, but they carry a powerful punch. Lightning, at over 50,000-degrees Fahrenheit, is about five times hotter than the surface of the sun.

Tracking lightning-caused ignitions is unpredictable. Lightning strikes can also cause holdovers, or when a fuel, like a tree, smolders from the inside out for five to 10 days after lightning strikes.

Lightning-struck trees themselves bear a permanent mark: a spiral of peeled-off bark running from the top of the tree down the truck.

Or, the tree can just completely explode.

“That’s pretty impressive,” Godson said. “If you take a 100-foot tree that is 30 inches in diameter, then it’s struck by lightning and it explodes, parts of the tree are scattered up to 100 feet away.”

That’s what happened a month ago in the Pagosa Ranger District near the Weminuche Valley. “Three-quarters of the tree is just turned into very large toothpicks,” he said.

The fire environment is complex, including weather, fire fuels and topography. For natural ignition wildfires, fire agencies need to know where to look and when lightning struck to determine fire risk. One way they do that is by tapping into data gathered from electromagnetic waves and infrared satellite imaging.

For the U.S. Bureau of Land Management, NASA feeds data to a mapping program using a near-infrared optical transient detector on the nation’s first environmental satellite, GOES-R.

Vaisala, a Finnish company that operates the National Lightning Detection Network, also contributes data to the federal system.

Like a pebble falling into a pond, lightning causes ripples in the electromagnetic field. For 30 years, the network of about 120 sensors, each with a range of 1,000 miles, tracked lightning around the country, said Brooke Pearson, global solutions manager for Vaisala.

The sensor and satellite data can also determine location to within 500 feet, strength of the charge, whether the bolt connected with the ground, charge characteristics and more.

“Lightning is not equal. Some lightning is far more likely to start a wildfire than others,” Pearson said.

Cloud-to-ground lightning is most destructive when it has something called a continuing current. These strikes happen 5% to 10% of the time and last up to 1,000 times longer – generating more heat and causing more fires, he said.

Vaisala users will be able to track continuing current lightning in a beta version of the mapping program for the first time this fall, Pearson said.

The data will be shared with federal wildland firefighting crews via the Durango Fire Interagency Dispatch Center.

When dispatchers receive a smoke report from the public, they pass along lightning location data – at times accurate to within a tenth of a mile – and other fire environment data to fire managers.

“This can help us start to think, before the fires are even known of; we can go on here, look at where the lightning is, and start imagining what our response will be in certain areas,” Williams said.

New technology is even making its way to wildland firefighters on the ground. At the county level, fire agencies use mobile phone applications to track lightning in the field. In the last five years, fire agencies have started using buzzing, insect-like drones.

This summer, Upper Pine River Fire Protection District joined the trend. The department’s new $5,000 drone system is quickly becoming invaluable, said Shea Allen, firefighter and lead drone pilot.

In the past, crews would either have to send a crew member or an aircraft to determine fire risk after a lightning cycle passed through. Those options put humans at risk, take time to coordinate and/or cost too much, he said.

Now, crews can fly the drone to assess the area if they hear a smoke report and know that lightning has passed through. The gadget has a 3-mile range and instant video feed, so pilots can determine if an area is at risk for a fire from a safe distance.

“When you’re operating a drone, the risk is minimal,” Allen said. Not only that, it’s cheaper, faster and more efficient.

For Allen, drones are the tool of the future.

In 10 years, if someone ordered a firefighter onto a burning roof to assess the damage instead of sending a drone, “people would think you’re a dinosaur,” he said.

smullane@durangoherald.com