DENVER (KDVR) — Just how did the Marshall Fire jump from burning in grasslands to devastating suburban neighborhoods?
Rocco Snart, planning branch chief with Colorado Fire Prevention and Control and expert on fire behavior, explained how the fires in Louisville and Superior could do so much damage.
Snart said it was the result of a catastrophic combination: “fuels, weather and topography.”
It all started with dry vegetation.
“When they’re healthy and moist, they really do really well,” Snart said of brush and trees in the foothills. When the moisture is scarce, dry grass and trees will burn, putting embers in a bad place: “close exposure to other fuels,” he said.
Embers are like snowflakes. When flakes fall on grass, trees or homes, they melt or pack. But embers burn at high temperatures, and when they’re flying in the wind, they’re a wall of fire.
“A lot of folks have ornamental fuels around their house. Whether it’s a juniper or a nice evergreen of some kind,” Snart said.
When embers pack on trees and brush, the flames go from grasslands to neighborhood adjacent trees.
“In an ember shower, they look just like (snow), except they’re red hot,” Snart said.
When those trees burn, embers are sent to their next destination: homes, where fuel is abundant.
“Fences, you have decks, you have yard furniture and then you have houses that have some kind of combustible siding perhaps,” Snart said.
The result of embers on any structure is what happened in Superior and Louisville: indiscriminate destruction.
“It could have been in Golden; it could have been up near Fort Collins. It was just at the wrong place at the right time,” Snart said.