Archival August 2023 - Selected Browning of Conifer Cultivars in the 2021 Pacific Northwest Heat Wave

Despite our unusually cool, wet, and rainy springs in the Pacific Northwest the past few years, we still remember and cannot forget the record-breaking heat wave that blasted us in late June of 2021 elevating day- time temperatures 40 degrees higher than usual for early summer. This extraordinary event broke all-time records for the hottest temperatures in our region.

A nearly stationary, high-pressure system parked atop western North America for several days, blocking the easterly flow of weather systems typical for our region, forcing warm air downward and preventing sur- face heat from escaping into the upper atmosphere. This exceptional heat dome of parched, stagnant air remained trapped over northwestern North America for less than a week but pushed temperatures in Lytton, British Columbia, to 121°F, the highest temperature ever recorded in Canada, and to highs of 108°F in Seattle and 116°F in Portland, Oregon. These oven-like temperatures, in combination with profoundly low relative humidity, meant little evaporative cooling as well, further contributing to punishing high surface temperatures and desiccated soils. More than a year later, many of the scars and casualties of the daunting heat dome of 2021 remain.

Download John J. Albers’ and David Perry ‘s article published in the Conifer Quarterly