Labor Day 2020 brought hot, dry, easterly winds across the west coast, fanning record-breaking megafires that threatened suburbs and compromised air quality in cities like Portland Oregon, shown here. Photo by Ted Timmons.
Labor Day (Sept. 7) 2020 brought with it a storm that knocked out power to more than 100,000 people in the Pacific Northwest. Hot, dry, easterly winds reached hurricane levels. Numerous wildfires that had started in August across California, Oregon, and Washington exploded when fanned by the gusty winds. Some coalesced into record-breaking megafires, burning millions of acres and spurring widespread evacuations from suburbs that were taken by surprise.
Like millions of other residents in the region, station employees were glued to the news as numerous fires encroached on nearby communities. Some had to evacuate, some prepared to evacuate, and some got to work almost immediately to begin studying the causes and effects of these devastating fires.
Was this just another fluke in a year that seemed to bring a conveyor belt of bad news? Or do Pacific Northwest residents need to adjust to a “new normal” for wildfires and the resulting poor air quality from smoke?
The station had shown remarkable foresight several years earlier by launching the West-Side Fire Research Initiative. The initiative is dedicated to understanding wildfire behavior in the western parts of Oregon and Washington, and how it differs from more familiar wildfire behavior in the closely studied, disturbance-prone eastern portions of these states.
The West-Side Fire Research Initiative arose in 2018 out of growing concern for exactly the scenario that came to reality in 2020. Long-held perceptions that rainy, west-side landscapes were immune to wildfire were beginning to wear thin. Historically, fires were rare in these lush forests on the west side of the Cascade Range. Although fires did happen, conditions had to be exactly right for them to start; when they did, they tended to be large and stand replacing.
However, over the past two decades, the length of fire seasons has increased, and warm dry conditions have become more common in Pacific Northwest forests. While the probability of wildfires on the west side is still lower than on the east side of the Cascade Range, wildfire risk and the magnitude of consequences of a very large fire event are high, as 2020 tragically showed, especially in areas with wildland-urban interface.
Brian Potter, a research meteorologist with the station, studies wind events that can drive fire behavior in southwest Oregon. Air flowing onshore from the Pacific Ocean along Oregon’s coast has historically complicated fire management in this part of the state. These situations, known as “marine layer events,” are particularly challenging in the Umpqua, Rogue, and Chetco River drainages.
Potter acknowledged that forecasting the marine layer along the West Coast during wildfires can significantly modify fire behavior.
“The cooler, moister marine air reduces fire spread rate and intensity,” he said. “However, no two marine layer events are the same, and the depth, extent, duration, and daily variability of any particular event are crucial to the development of fire management strategies and resource deployment.”
Potter’s study team set up weather monitors along the Rogue River drainage to get a finger on the pulse of the marine layer: Where will it go? How long will it stay? How deep will it be? His project is a crucial first step to understanding this complex three-dimensional problem. The team ultimately hopes to increase confidence and precision in observing when and where the marine layer is influencing a fire.
Some of the other research underway as part of the initiative is addressing additional information requests from land managers, such as better understanding of historical fire regimes in west-side forests, evaluating future fire regimes, understanding hazardous fuels management by landowners, examining postfire vegetation dynamics (live and dead), and implications for potential future fire behavior.