Developing a Scientific and Readily Usable Tool for Assessing Daily Wildfire Risk in Southern California

A climatology of large wildfires was developed and studied over the domain of the Southern California Geographic Area Coordination Center (OSCC) from 2009-2021. That climatology, over the same period, was compared against the history of High Risk fire weather days forecast by the OSCC Predictive Services unit, responsible for providing fire weather data to numerous interagency wildfire management partners at the federal, state, and local levels. The results showed that a strong majority, 78%, of central and southern California wildfires occur in the summer months, from June through September. However, results also showed that a majority, 57%, of High Risk forecasts are issued by meteorologists in the fall and early winter from September through December. This corresponds to Santa Ana wind season, and while Santa Ana driven wildfires are prone to devastating impacts, they are nonetheless a statistical minority. The gap identified by this research highlighted a need to improve communication of elevated fire weather danger by the OSCC Predictive Services unit, particularly during the summer months. Using the newly developed climatology, a recommendation and possible solution has been proposed to address this gap in communication, using a probabilistic forecast approach. The climatology itself, as well as a more comprehensive review of the problem of communicating elevated fire danger, and a proposed solution, are presented here.