Over the days of 25 June - 29 June 2021, there was extreme heat in western North America
The US states of Washington and Oregon, as well as the Canadian Province of British Columbia, all achieved all time record maximum temperatures.
Many of the charts, below, come from a US list-serve.
COMMENTS ON LARGE SCALE FEATURES
This first image, provided by Dr Paul Roundy at the University of Albany, shows was the early predictors were for this event.
...
Some discussion that took place prior to the event. From Paul Wolyn:
"The GFS and EC have southeast flow at 850mb over the OR and WA. Could the southeast flow advect the heating from the elevated mixed layer over central Oregon into the PDX and maybe the SEA area? Much of central Oregon is at 4000 to 5000 feet MSL. I wonder if this could be contributing to the extreme temperatures in the model runs. It could be the "perfect" combination of many factors leading to the extreme heat."
COMMENTS ON LOCAL FEATURES
Higher resolution models, such as the WRF run at the University of Washington, added details to this picture:
...
This extreme heat event was predicted well in advance. At that time, as what was being predicted was something that had not been seen before, there was plenty of conversation about if this was indeed real - or some sort of model error. It did turn out to be true.Some observations about what then took place.
COMMENTS ON OBSERVED WEATHER
First - the observed 500mb height from Quilayutte, WA, USA, and the historical soundings for that site:
...