Forest damage assessment after storm Johannes in central Sweden (2025-12-27)

Storm Johannes, occurring on 27–28 December 2025, affects northern and central Sweden with severe winds, snowfall and extensive forest disturbance, generating widespread windthrow across large forested regions. The Swedish Civil Contingencies Agency (MSB), in coordination with the Swedish Forest Agency, requests the activation to obtain an integrated assessment capable of characterising storm‑induced forest damage under winter conditions. The analysis focuses on multi‑temporal SAR change detection to delineate affected forest areas and on estimating windthrown timber volume by integrating national forest attribute datasets. The outcomes aim to support authorities in understanding damage severity, prioritising field inspections, planning post‑event recovery and coordinating actions with forest owners and relevant national stakeholders.