Aerial infrared maps tell the striking story of how the intense flames of the 416 Fire consumed 7,180 acres in eight days.

The precise images taken by U.S. Forest Service planes each night help to guide firefighting decisions about where to send crews and predict the fire’s movements 24 to 72 hours into the future, said Rob Mattox, a geographic information systems specialist.

Earlier this week, it was clear that the fire was going to keep growing.

“This is going to be a long duration event,” said Shawn Bawden, a spokesman with the Type II team.

Particularly on its inaccessible western side, heavy fuels were expected to keep the fire moving, Mattox said.

“Anywhere it’s an open fire, it’s going to keep moving,” he said.

The thermal imaging that is key for guiding firefighting strategy must be done at night because the ground, trees and vegetation cool off, while the fire maintains its heat, he said.

Those areas that have already burned also cool down, so the active flames near the outer boundary of the fire show up as the most intense heat, he said.

The maps also show spot fires, which allows firefighters to find and extinguish them.

The thermal imaging can be done even in heavy smoke, which can obscure observations on the ground, Bawden said.

“It’s hard to see, even if you are close to the fire,” he said.

While the imaging functions in smoke, it can’t work in heavy cloud cover. But that hasn’t been a problem on the 416 Fire thus far, Mattox said.

Two planes, a Cessna Citation Bravo II and a Beechcraft Super King Air 200, provide images of fires burning across the country for the U.S. Forest Service. As of Friday afternoon There are 13 fires burning in Arizona, New Mexico and Colorado, according to the Inciweb, a national database of wildfires.

If the federal team requests a thermal image, one of the planes can scan the landscape of the 416 Fire before moving on to other fires, Mattox said.

The infrared images must be overlaid onto a map later, and an interpreter will then delineate the areas that are hot and cool, Mattox said. Mattox receives completed maps to distribute.

The state has also done similar aerial imaging of the 416 Fire, he said. Colorado owns two Pilatus PC-12 airplanes staffed by sensor operators that capture individual GPS points. Those points are used to determine the fire’s perimeter and the location of spot fires.

Field observers near the blaze also collect GPS information about the fire’s location to supplement aerial imaging, Mattox said.

“They are all tools in the tool box,” he said.

Information collected by the Forest Service planes is also publicly available, and anyone can use it to build maps.

For example, Joseph Elfelt, a semi-retired software developer in Washington, builds maps of major wildfires across the U.S. every morning and allowed The Durango Herald to share his interactive map of the 416 Fire.

It takes him about a half an hour to prepare each map using data from the Forest Service, NASA and the National Weather Service. He also culls information for the U.S. Geological Survey to build maps of potential mudslides.

He said he hopes evacuees use his maps to find authoritative and detailed information about the fires.

“I am showing them data that they don’t really see anywhere else,” he said.

mshinn@durangoherald.com