An analysis of a extreme wind event in the Basque Country : the 23 october 2022 case

A wind event is analysed during the passage of a depression over the Bay of Biscay. From the northwest of the Iberian Peninsula, it moves in a northeasterly direction until it finally reaches the south of the British Isles. In the upper layers, the flow is strong from the southwest. This configuration generates intense southwesterly winds, especially in central hours and especially in Alava, with Vitoria-Gasteiz being one of the towns most affected. Wind gusts of more than 120 km/h are recorded in exposed areas and more than 100 km/h in non-exposed areas, for example at the Gasteiz station a wind gust of 124 km/h is recorded (third highest record in the Gasteiz station data series). In addition, the high temperatures, the strong wind and the state of the vegetation mean that the risk of forest fires is high and, in fact, a major fire takes place in the Balmaseda area (the most significant fire in Bizkaia in the last 30 years). Due to the wind, there were numerous incidents caused by falling trees, obstacles on the road, falling electricity and telephone poles, flight diversions, etc.

The wind gusts initially forecasted were exceeded. Wind gusts between 80 and 100 km/h were expected in non-exposed areas, but these values are exceeded punctually in many stations. The data from the stations are analysed and compared, and the factors that could have caused the wind to increase over than expected are studied.

The synoptic and mesoscale factors of this episode are analysed. The information from Basque Country Automatic Weather Station Mesonetwork is reviewed, analysing the spatial-temporal evolution of the wind at different locations. After analysing the situation, different conclusions and key factors to be taken into account from the point of view of forecasting are extracted.