Unprecedented Heatwave in Western North America during Late June of 2021: Roles of Atmospheric Circulation and Global Warming

Abstract An extraordinary and unprecedented heatwave swept across western North America (i.e., the Pacific Northwest) in late June of 2021, resulting hundreds deaths, a massive die-off sea creatures off coast, horrific wildfires. Here, we use observational data to find atmospheric circulation variabilities Arctic-Pacific-Canada patterns that co-occurred with development mature phases heatwave, as well pattern, which coincided decaying eastward movement heatwave. Climate models from Coupled Model Intercomparison Project (Phase 6) are not designed simulate particular event like this one. Still, show greenhouse gases main reason for long-term increase average daily maximum temperature past future.