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Notable Impact of Wildfires in the Western US on Weather Hazards in the Central US

Presentation Date
Thursday, December 15, 2022 at 11:00am - Thursday, December 15, 2022 at 11:10am
McCormick Place - E350



Increased wildfire events constitute a significant threat to life and property in the United States (US). Wildfire impact on severe storms and weather hazards is another pathway that threatens society, for which our understanding is very limited. Here we use unique modeling developments to explore the impacts of wildfires in the western US (mainly California and Oregon) on precipitation and hail in the central US. We find that the western US wildfires notably increase occurrences of heavy precipitation rates by 38% and significant severe hail (2 inches or larger) by 34% in the central US. Both heat and aerosols from wildfires play an important role. By enhancing surface high pressure and increasing westerly and southwesterly winds, wildfires in the western US produce (a) stronger moisture and aerosol transport to the central US and (b) larger wind shear and storm-relative helicity in the central US. Both the meteorological environment more conducive to severe convective storms and increased aerosols contribute to the enhancements of heavy precipitation rates and large hail. Moreover, the local wildfires in the central US also enhance the severity of storms, but their impact is notably smaller than the impact of remote wildfires in California and Oregon because of the less severity of the local wildfires. As wildfires are projected to be more frequent and severe in a warmer climate, the influence of wildfires on severe weather in downwind regions may become increasingly important.

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