HERMOSA – Tucked away in back of Animas Valley Elementary School, which is housing the 416 Fire incident command post, is a room filled with computers, maps and models of the fire’s path. Here is the makeshift office of the fire-behavior analysts.
“We’re the Geek Squad of the firefighters,” said fire-behavior analyst Glen Lewis.
Lewis is one of two fire-behavior analysts on the Rocky Mountain Type I team battling the fire. His job is to determine the fire’s intensity and to help devise tactical and strategic decisions.
Fire officials use infrared imagery from an overnight flight to map the fire’s size. The infrared imagery catches all hot spots, which a member of the GIS team will compile into an accurate acreage number.
Lewis, who has been a fire-behavior analyst since 2004, uses this data to predict fire behavior. He analyzes fuels ahead of the fire’s expected path to determine the growth and speed of the fire. He also works closely with the incident meteorologist to determine how the weather will affect the fire’s intensity.
There are two segments of the 416 Fire – each producing separate fire behavior. The fire near the northern end of the perimeter has slowed as it runs into lighter fuels, such as aspen trees, that are less likely to burn. The fire has been extremely active on the south end as it burns conifers. The fire in that area has generated profuse short-range spotting that accelerates the heat pulse that can get into trees and spread the fire.
“As dry as it is, it’s really been wanting for the last several days to make a significant run,” Lewis said. “They’ve really done a good job of being able to control that and do it on their terms versus doing it on the fire’s terms. They had a chance to get in front of it and were prepared.”
When a tree burns, it lofts embers that can start fires. In normal conditions, it’s unlikely those embers will start fires. However, with the dry conditions that the area is facing, the possibility increases.
“When the trees are this dry, the probability of those embers burning when they land is really very high,” Lewis said.
[image5:]Crews need to assess fire size when determining how to combat burning embers. If the flames aren’t very large, grounds crews will use torches to create a burn zone where the embers can fall. Larger flames indicate a higher fire intensity, and crews will usually depend on an air attack. The particular terrain of the 416 Fire has also made it extremely difficult for grounds crews to hike up and use torches.
“Walking a 20-person crew up there across that slope trying to light it up with a torch, obviously, we wouldn’t do that,” Lewis said.
In an effort to combat the terrain, crews have conducted multiple burnouts in the southern portion of the fire to prevent its spread. Hand crews and dozers get ahead of the fire and create a fire line, or a safe space that hopefully prevents the fire from immediately spreading. Helicopters will then use Plastic Sphere Dispensers, a device that shoots spheres, the size of pingpong balls, ahead of the fire’s path before the fire line. The goal is to create a burn zone ahead of the fire so when the embers inevitably fall, they are falling on fuels that have already been burnt, which reduces the chances of spot fires on fresh fuels ahead of the fire’s path.
“You’re generally trying to burn against the way that the fire wants to spread,” Lewis said. “Once you’re able to do that and eliminate a lot of the fuels, then you’ve increased the distance. By burning it out and blackening that, you can double, triple, quadruple or even more the area that won’t burn. The fire would have to throw those embers farther in order to spot across the line.”
The PSDs can drop as few or as many spheres as they wish, depending on the desired fire intensity.
“The operator has a lot of control,” Lewis said. “That’s what’s so important about having skilled people doing that because they really control the intensity of the fire down near that line. They have quite a bit of control of how much fire they get up there.”
The burnout operations tend to release a lot of smoke in the air, which has caused onlookers to gawk at the plumes forming above Hermosa. The differing colors of the plumes indicate the intensity of the fire. Light-colored smoke indicates lighter fuels that are burning slower, while dark smoke typically indicates a stronger burn.
“That’s a really intense fire when you start seeing that happen,” Lewis said. “It’s burning so quickly that it can’t burn all of that matter.”
Crews try to keep burnouts at as low of an intensity as possible but hot enough that they can consume the fuels that need to be removed ahead of the advancing fire.
“You’re really trying to clean that up and leave as much as you can,” he said.
During the first few days of the 416 Fire, it spotted over certain areas, leaving swaths of vegetation untouched by the flames. It is a marked difference from this week, in which super-heated flames have blackened entire mountainsides. Lewis credits that to the variety of fuels in the areas where the fire initially started compared with the conifers that burn easily. He noted that a hot and dry week also can change conditions: Trees that may not have burned on June 1 when the fire started may be more susceptible two weeks later.
“We are a week drier,” Lewis said. “It keeps getting hotter and drier all the time. You can take a week of hot and dry weather, and fuels will go from being dry and they will burn under certain conditions to being really dry, and they’re just going to burn no matter what.”
The weather outlook for Friday will be more of the same. There is a chance of moisture Saturday and Sunday, but Lewis doesn’t expect it will significantly alter the fire’s behavior.
“Because it’s so dry, this pulse of moisture – depending on how much comes – it can knock down the fire for a day or two,” Lewis said. “As soon as it warms back up, we’re right back in it. A day or two of rain is not going to put this out. It’s that dry.”