Smoke Signals and Severe Weather: Deciphering the Unprecedented Impact of Canadian Wildfires on Midwest Forecasting via Radiative Transfer

Recent years have witnessed a surge in wildfires, resulting in transboundary air pollution episodes with far-reaching implications. As wildfires gain severity within a warming climate, their influence on extreme weather in downstream regions, like the Midwest, has garnered attention. While the impact of smoke on air quality weakens over distance, transported smoke significantly disrupts the atmosphere's energy balance. Solar radiation interacting with wildfire aerosols triggers temperature shifts and atmospheric stability changes, thereby shaping weather patterns. Studies indicate that transported wildfire smoke can exacerbate hazardous weather in central and Eastern U.S., potentially intensifying heavy precipitation and large hail, while paradoxically suppressing severe weather events.

This study centers on an unprecedented air quality event in June 2023 and the 2022 transport of California wildfire smoke. Using the Fu-Liou-Gu Radiative Transfer Model (RTM), we explore the intricate radiative effects of these smoke events on atmospheric heating rates and fluxes over the Midwest, particularly Wisconsin. We leverage high-resolution aerosol and atmospheric profiles from the University of Wisconsin-Madison's Cooperative Institute for Meteorological Satellite Studies (CIMSS) via their High Spectral Resolution Lidar (HSRL).

Furthermore, we assess how accurately models and reanalysis captured these events and their implications for heating rate changes. To achieve this, we conduct RTM calculations using aerosol and atmospheric profiles from NASA MERRA-2 reanalysis and the High-Resolution Rapid Refresh (HRRR) model. A comparative analysis of FLG model outcomes against HRRR and MERRA-2 outputs underscores the significance of understanding smoke's radiative properties and broader meteorological impacts. This provides insights into the evolving landscape of challenges associated with forecasting smoke-related phenomena.

Ultimately, our study bridges the gap in understanding the effects of long-range transported biomass burning aerosols on severe storms. We specifically investigate how these events suppressed forecasted severe weather in the region (June 2023), or how they could potentially have the opposite effect (September 2022). This emphasizes the intricate relationship between transported wildfire smoke, aerosol properties, atmospheric radiative processes, and complex severe weather patterns.