The first ghost of the Swan Lake Fire showed up on Tuesday east of Soldotna.
With big wildland fires that burn deep into the terrain, pockets of hot material can remain, even into the next year. These hotspots can then ignite and cause a secondary burn, called a holdover fire.
This week’s holdover burn was small, only about ten feet square, smoldering in the duff, and firefighters had it out in ten minutes. Division of Forestry Statewide Public Information Officer Tim Mowry said it was visible from the Sterling Highway, where passing drivers saw it and reported it.
Holdover fires are not uncommon in Alaska, where the peat and in the terrain can hold heat all winter. Mowry said the snow, rather than putting them out, can actually insulate the heat and essentially bank it for the next year.
"Last year, things were so dry, we had record high drought around many parts of the state, including the Kenai Peninsula, so the fires burned really deep down into that duff," he said. "We had reports of fires burning two, three feet deep. When fires burn that deep, they can find a pocket of peat and get embedded in there and then when it does snow, that snow sort of serves as insulation. Sort of like a snow cave—you can build a snow cave, and it’s above freezing in there."
Holdover fires are somewhat common in years following big burn years, Mowry said. They aren’t necessarily all that dangerous when they’re in the middle of the burn scar, but when they’re near the perimeter, they can ignite new fires.
Rain and snowmelt may not be enough to extinguish them. If the weather gets hotter and dryer with more wind, there could be more, he said.
"If conditions persist where we get warm, dry weather," he said. "We’re expecting to see more, not just from the Swan Lake Fire but from other fires as well."
The Swan Lake Fire started with a lightning strike in June 2019 and burned down significantly in July, but extremely dry conditions and high winds in August fanned it up again. Ultimately, it burned more than 167,000 acres, shut down the highway intermittently, and cost about $50 million to fight.
Reach Elizabeth Earl at eearl@kdll.org.
