Enhanced Pacific Northwest heat extremes and wildfire risks induced by the boreal summer intraseasonal oscillation

This study investigates the influence of the boreal summer intraseasonal oscillation (BSISO) on heat extremes and wildfire risks in the Pacific Northwest (PNW). The research reveals that during BSISO phases 6-7, the likelihood of heat extremes and fire-conducive weather conditions in the PNW increases significantly (by ~50-120%). This is primarily attributed to enhanced diabatic heating over the tropical central-to-eastern North Pacific, generating a downstream wave train that results in a high-pressure system over the PNW. This system promotes surface warming through increased surface radiative heating and enhanced adiabatic warming. The findings suggest a pathway for improving subseasonal-to-seasonal predictions of heatwaves and wildfire risks in the PNW by better representing BSISO heating in climate models.

Sandro W. Lubis, Ziming Chen, Jian Lu, Samson Hagos, Chuan-Chieh Chang, L. Ruby Leung