The 2021 Pacific Northwest Heat Wave and Associated Blocking: Meteorology and the Role of an Upstream Cyclone as a Diabatic Source of Wave Activity

We investigate the meteorological and dynamical conditions that led to extreme heat in Pacific Northwest from late June early July 2021. The was preceded by an upper-level atmospheric blocking snatched a warm pool of air lower latitudes. A heat-trapping stable stratification ensued within anticyclone, raising surface temperatures significantly. An upper-tropospheric wave breaking concomitant cyclogenesis off coast Alaska initiated block formation. regional local activity budget reveals localized diabatic source associated with this storm critically contributed enhanced zonal flux downstream, whose convergence over Canada drove blocking. simple reconstruction based on observed predicts 41 percent reduction strength 10-degree eastward displacement when upstream is reduced just 30 percent.