I thought this Oregonlive news piece by Ted Sickinger was interesting, as I had never heard much before about western Oregon fire history. The story is very long and very interesting, with many parts we could discuss. Excerpt below. I recommend reading the entire piece.
East wind events:
The strong and persistent windstorm that started Monday and stoked the big fires is unusual, but academics say similar conditions were a prime factor in many of the most infamous, fast-running west-side conflagrations since Europeans settled in Oregon.
Those include the 1902 Yacolt Burn, which torched 500,000 acres in Southwest Washington and parts of Oregon and killed at least 65 people. Easterly gales were a main ingredient in the Tillamook Burn of 1933, which initially burned 40,000 acres west of Gales Creek over 10 days, then devoured an additional 200,000 acres in 20 hours when stoked by hot east winds. East winds were also implicated in the Bandon fire of 1936, which burned 143,000 acres, consumed the town of 1,800 and killed at least 10 people.
In 1957, Owen Cramer, a meteorologist at the U.S. Department of Agriculture’s Pacific Northwest Research Station, authored a paper describing the close relationship between occurrences of severe easterly winds and large forest fires in northwest Oregon and southwest Washington.
“The history of forest conflagrations in the Northwest is, for the most part, a history of the simultaneous occurrence of small fires and severe east winds,” he wrote, going on to describe the exact weather pattern that took place on Labor Day. “Under these conditions fires run wild and fire-control men must be prepared for the worst.”
Daniel Donato, a natural resource scientist at Washington Department of Natural Resources, is currently studying the relationship between east wind events and large fires. He says there’s ample precedent and it’s fair to say it’s characteristic of the landscape west of the Cascades.
He likens it to the recent awakening around the likelihood of a Cascadia subduction zone earthquake. “We get lulled into this sense that it doesn’t happen here. It’s a California problem. But it does happen here, with low frequency,” he said.
Dan Gavin is a geographer at the University of Oregon who studies the history and pattern of fires in wet forest types west of the Cascade Range. He says the best evidence of pre-European, west-side megafires comes from core samples of remaining old-growth trees in protected areas and tree-ring studies in stumps from 1980s clearcuts. Coupled with sediment studies, they show that big fires have been a constant presence on the landscape for at least 11,000 years, leaving uniformly aged stands of Douglas-fir across Western Oregon and Washington at intervals of 100 to 250 years.
In the hierarchy of factors that dictate how fast and far a fire will burn – fuels, topography and weather – wind speed and direction are key drivers. And since those fires have no obvious ignition source, he says, they were likely either “lightning holdovers” or fires set by indigenous tribes along hunting routes that smoldered for days to weeks before a hot and persistent east wind kicked up, bellowing the fires and preventing the typical nighttime increase in relative humidity that comes with normal westerly marine flows.