Three Typhoons in Korea Amplified Wildfires in Oregon
Three typhoons in the western Pacific that ran into the Korean Peninsula within two weeks of each other. Together, Typhoon Bavi, Typhoon Maysak, and Typhoon Haishen each contained enough energy to perturb the jet stream – creating an atmospheric wave train that enhanced the hot, dry weather of the western United States. This study uses forecast models and weather observations to show that these typhoons amplified areas of high and low pressure in North America leading to the intense winds which rapidly spread fire in Oregon, Washington, and California.
While the impacts of climate change on these events were not evaluated in this study, the implication is that the effect of weather extremes that are known to be exasperated by climate warming are not always limited to the region in which those extremes occur.
For the catastrophic fire outbreak in early September for western North America, three north Pacific typhoons amplified pre‐existing fire‐weather and the local pressure gradient – catalyzing an anomalous down‐sloping wind event in Oregon. Each typhoon tracked far enough north to perturb the mid‐latitude flow – with the quick succession of storms (within two weeks of each other) serving to maintain and continually amplify the downstream circulation. Additionally, our results from the historical GEFS 16‐day forecasts combined with reanalysis data support forecast models as a useful tool for rapid synoptic attribution of extreme weather events. Using this process, we determined the difference between possible atmospheric scenarios for realistic typhoon forecasts and missed typhoon forecasts.