Atmospheric precursors of forest fires: development of the Fire Sentinel Index (FSI) in the Abruzzo Region.

In recent years, Italy is facing severe emergency linked to fires. According to the latest reports, over 53,000 hectares of vegetation were lost in 2023, due to arson or negligent fires. Consequences on ecosystem and natural equilibrium are relevant, since the time for the natural restoration process may take several decades. Climate extremes exacerbate Mediterranean area fire risk, due to prolonged drought conditions. On the other hand, hydrogeological risk is also expected to increase over burnt slopes, where surface runoff is incremented due vegetation loss. According to the current legislation, fire risk management is in charge of the Italian Regional Civil Protection (RCP), therefore the development of user-oriented tools, able to prevent the fire hazardous conditions, is key element to ensure the forest-fire risk management. In the proposed model, the atmospheric conditions preceding a forest fire are estimated though the combination of air temperature and relative humidity, as reference of atmospheric parameters. The approach assesses how many times the observed air temperature and RH of the previous 12 days area above the critical conditions (i.e., >25°C and < 50%, respectively). The model calibration and validation are carried out by using a three-years dataset of Abruzzo Region forest fires dataset, that hit the Abruzzo region from 2018 to 2020, combined with meteorological data from civil protection gauges’ network. The developed index identified fire-precursors in the 80% of selected case studies. The missing 20% is mainly related to the meteorological uncertainty in poorly gauged areas. Starting from the index validation, a pre-operational tool forced with European Centre for Medium-Range Weather Forecasts (ECMWF) analyses is also described. The hazard forecasts based on Fire Sentinel Index (FSI), are operational for forest and interface fires forecasting activities on the Abruzzo region, in the framework of a specific agreement signed with the Abruzzo region Civil Protection Agency. The results related to the use of the FSI during the last forest fire prevention campaign that occurred in summer 2024 in the Abruzzo region will be highlighted.