The NOAA/NWS Storm Prediction Center (SPC) has had a fire weather program for more than 25 years. In addition to issuing fire weather outlooks, SPC also conducts fire-related research and development. Recently, we focused those efforts on evaluating weather inputs necessary to create gridded analyzed and forecast National Fire Danger Rating System (NFDRSv4) output. We completed detailed evaluations of surface stations compared to gridded analysis and forecast data for fire weather and fire danger variables. We also generated seasonal and annual climatologies, including percentiles, at every grid point to provide a climatological perspective for fire danger. Forecast weather data sources were evaluated against RAWS observations and a gridded-based climatology. We focused on choosing operational, consistent, and similarly distributed data sources for both observed and forecast weather data. We are now producing daily gridded analyzed and forecast NFDRSv4 output using Fuel Model Y in support of SPC and soon-to-be NWS-wide fire weather operations.

With foundational climatological weather and NFDRSv4 data developed, we began evaluating the Red Flag Warning Matrix (Jakober et al. 2023) and SPC Fire Weather Outlooks. The Red Flag Matrix product was designed as an operational guidance tool for Red Flag Warning/Fire Weather Watch decisions. The Red Flag Matrix sums three categorical scores based on historical percentile ranges associated with daily extreme fire spread for relative humidity, wind speed, and energy release component. Operationally, the percentiles are based on forecasts and converted to the categorical scores. Larger scores indicate that all three environmental elements combined show increased potential for Red Flag conditions. The matrix was refined and evaluated based on fire spread, intensity, and occurrence data. Daily matrix data from 2020-2025 is available for event review purposes, with daily forecast data soon to be available for NWS offices.