SmokePath Explorer - a data driven smoke management tool to support prescribed fire planning in California, USA.

SmokePath Explorer is a web-based decision-support tool for California, U.S.A. that quantifies smoke transport probability and population exposure risk across the state, enabling data-driven strategies to minimize impacts while advancing fire management effectiveness. SmokePath integrates the California and Nevada Smoke and Air Committee (CANSAC) high-resolution (2-km) 20-year reanalysis climatology with HYSPLIT trajectory modeling. A total of 1.3 billion transport trajectories were precomputed with initializations four times per day at four distinct height levels capturing diurnal variations and injection height influences across various prescribed fire scenarios to support probabilistic smoke projections. Within the SmokePath online dashboard, users can input fire parameters and select specific months or weeks to assess smoke transport risk. The tool generates risk-level smoke transport contours from precomputed data and summarizes key meteorological variables. The system also provides population exposure estimates, including the total affected population, the number of smoke-sensitive facilities (i.e. educational and healthcare), and impacted USPS ZIP codes. User feedback has been key to developing SmokePath, enhancing usability, data integration, and decision-making for prescribed fire planning. To assess SmokePath's efficacy, we conducted case studies across diverse regions and validated results against independent observation datasets. These use cases assessed the accuracy of the WRF-CANSAC reanalysis dataset, which serves as the meteorological input for fire weather climatology and trajectory modeling. The fire case studies focused on identifying optimal burn windows and quantifying smoke transport patterns from (i) large multi-day prescribed fires, (ii) short duration (single-day) pile burns, and (iii) burns across diverse regions with complex topographic features. In most cases, modeled transport probability aligned with satellite-observed smoke plumes, capturing predominant dispersion patterns. Stakeholder feedback further supported the tool's practical utility - 85% indicated they would use SmokePath for prescribed fire planning, and 62% found it useful during wildfires.ImplicationsWith increasing number of catastrophic wildfires causing billions in damage and significant loss of life, California is set to dramatically expand fuel treatment efforts, including prescribed fire. While essential for wildfire mitigation, prescribed fires emit air pollutants that, if not carefully managed, can degrade air quality and pose serious public health risks. To confront these challenges - and in response to the state's Strategic Plan for proactive and consistent smoke management - we developed SmokePath. The tool provides evidence of expected smoke plume behavior for short-term and long-term planning. SmokePath's features help land managers prioritize prescribed fires during periods with minimal community impact, particularly for vulnerable populations. Beyond prescribed fire planning, SmokePath is a potential powerful asset for wildfire response, delivering climatology-based insights on smoke impacts to decision-makers for swift public communication and mitigation. By rapidly providing smoke risk information, the system will enable more timely public messaging regarding potential smoke exposure and mitigation strategies, particularly for disadvantaged communities. This functionality will help improve risk communication, allowing affected populations to take proactive measures to reduce exposure and protect public health, while advancing the strategic use of prescribed fire as a wildfire mitigation tool.