Assessing wildfire dynamics during a megafire in Portugal using the <scp>MesoNH</scp> / <scp>ForeFire</scp> coupled model

Abstract This study investigates the Serra da Estrela megafire, located in Portugal, which occurred in August 2022, aiming to explore how changes in weather conditions can modify fire behavior in a fire burning during several days. The study uses a set of fire–atmosphere coupled simulations, referred as EXPn. The MesoNH atmospheric model was coupled to the ForeFire fire propagation model and configured with three nested domains, each comprising a 150 × 150 horizontal grid, with resolutions of 1500 m, 500 m, and 250 m. Regarding the experiments, EXP1 [IGN] corresponds to the ignition phase on 6 August, EXP2 [PYRO] to the development of pyro‐convective clouds on 10 August, whereas EXP3 [REAC] represents the fire reactivation period on 15 August. The first and third periods showed that smoke plumes were transported mainly within the boundary layer, whereas in the second period pyro‐convection reached the middle tropospheric levels, allowing the formation of pyro‐convective clouds. Such clouds were confirmed from radar and satellite observations. Beside the fire‐generated clouds, the study highlighted that propagation of the fire front can suddenly shift due to the interaction between weather, fire and complex terrain. This study confirmed the importance of the use of coupled atmosphere–fire models to represent fire dynamics and their impact on local meteorology. In a global perspective, such an approach provides a framework for assessing wildfire–atmosphere interactions in diverse environments, supporting improved prediction of large wildfires. Overall, it underscores the influence of evolving atmospheric conditions on fire behavior, which is critical for understanding the development of megafires capable of burning over several weeks. This study highlights the crucial need to expand our scientific understanding of fire behavior, enabling its application to other regions worldwide.