Assessing Wind Gust Diagnosing Methods over Complex Terrain in the Basque Country

Accurate forecasting of wind gusts is essential for anticipating severe weather events, given their significant impact on infrastructure, transportation, and public safety. Wind gusts are strongly influenced by atmospheric boundary-layer processes, particularly turbulence and vertical momentum transport, which remain challenging to represent in numerical weather prediction models.

This study evaluates and compares the performance of two wind gust diagnosing methods: (1) an IFS-based scheme, which computes gusts using turbulent velocity scales derived from surface stress and atmospheric stability; and (2) a NOAA-based scheme (UPP method), which estimates maximum gust potential through momentum transport from the top of the boundary layer. Both diagnosing methods are implemented within a consistent high-resolution numerical modelling framework and validated using data from representative stations of the Basque Country automatic weather station network. The modelling setup includes a state-of-the-art turbulence closure scheme (MYNN) and a surface-layer formulation that accounts for thermal roughness as a function of vegetation height, ensuring a coherent representation of boundary-layer processes and surface–atmosphere interactions.

The validation covers approximately two years, focusing on severe wind events that occurred in 2024 and 2025 and had a notable impact in the Basque Country. The analysis distinguishes between exposed (e.g., coastal and elevated) and non-exposed (e.g., urban and valley) stations, reflecting differences in surface characteristics and boundary-layer conditions.

Results show that the NOAA diagnosing method generally performs better for non-exposed stations, while the IFS scheme—despite a general tendency to underestimate wind gusts—captures peak gusts more accurately in exposed locations. The findings also reveal sensitivity to wind direction and background atmospheric conditions, highlighting the influence of boundary-layer structure on gust representation. Although preliminary, this study provides a consistent evaluation of gust-diagnosing approaches under different boundary-layer regimes, supporting future improvements in operational wind forecasting at Basque Meteorology Agency (Euskalmet).