Ice dams in Seattle form when warm attics melt snow that refreezes at eaves, forcing water under shingles

https://griffinndea326.yousher.com/signs-your-renton-roof-has-storm-damage-1

Ice dams in Seattle form when warm attics melt snow that refreezes at eaves, forcing water under shingles. Continuous soffit-to-ridge ventilation, air sealing, and eave ice-and-water shield stop hidden winter leaks.