Board examines wildfire risk-modeling limits after January extreme-wind events

The Wildfire Safety Advisory Board devoted substantial discussion Dec. 3 to how electric utilities incorporate extreme-weather conditions into both operational decisions (like PSPS and device settings) and longer-term planning models.

Senior adviser Donald Richards summarized staff'led follow-up to an Energy Safety request: the three large investor-owned utilities (PG&E, Southern California Edison and SDG&E) responded that they use risk-informed criteria combining a fire potential index (FPI), fuel-moisture measures, circuit-specific risk scores and forecasted and near-real-time wind data. SDG&E, for example, told staff it can switch to higher-frequency station reads when gusts near critical thresholds.

But staff and several board members warned that many commonly used fire-spread models (Rothermel-based) were tested over a limited wind range (roughly up to 30 mph at modeling height), and extrapolating beyond those conditions could misrepresent fire behavior. "The models themselves are being pushed beyond their expected limits," Chair Jessica Block said, urging caution when planning for high-wind extremes.

Board members recommended additional sensitivity analyses, clearer documentation of how extremes affect planning-model outputs, and greater use of post-PSPS inspection data to quantify whether hardened infrastructure performs as expected during high-wind events. One member asked whether utilities track damage after PSPS events to better quantify mitigation benefits; staff said utilities submit post-PSPS incident reports to the CPUC and that the board would follow up on available data.

Staff said next steps will include drafting recommendations for the board that acknowledge model uncertainties, request greater transparency from utilities about modeling inputs and sensitivities, and outline how decision-making should combine model outputs with human judgment and real-time observations.

The board did not take formal action on modeling at this meeting but directed staff to prepare recommendations for future consideration.