To see more clearly, we have to start from the beginning: the beginning of this fiery episode.
A week ago, temperatures exceeded 30°C, particularly in eastern Canada (southern Ontario, Quebec and the Maritimes), a drought due to a lack of rain in May.
So all the ingredients were in place to set up a simple spark
Powder fireAs the saying goes.
The Maritimes, particularly Nova Scotia, were the first to be affected by these fires, but fires began to spread further west in Quebec.
However, a low-pressure system helped quell the flames in Nova Scotia, thanks to more significant rainfall. But, in the meantime, an atmospheric blockage — a weather phenomenon where conditions can last for days or even weeks — has kept the system nearly frozen over the ocean floor, increasing the flow of wind-borne smoke into the northeastern United States. Flow in opposite direction. This explains why winds, mainly from the north, pushed the smoke toward the United States.
In addition, another low pressure system that appeared in the center of the Atlantic Ocean slowed the system’s progress over the ocean, allowing significant amounts of rain to fall in the maritime provinces, but also in the north. Shore. Except that a low pressure system affects not only precipitation but also wind.
In the Northern Hemisphere, an anticyclone, usually responsible for good weather, has winds moving clockwise, while an air circulation moves counterclockwise around its center. Note that the directions are reversed for the Southern Hemisphere.
The depression responsible for the rain has so far been blocked offshore and has showered all of Quebec, a relief from the north shore, which has been ravaged by major fires in recent days. But as the system remained nearly frozen in eastern Quebec, the northeasterly winds did not change direction for several days.
Conclusion: A corridor was created to draw smoke from the Quebec fires into the United States. An atmospheric barrier pushed the wind toward Canada’s southern border.
It is important to point out that atmospheric occlusion is not a rare phenomenon, but its occurrence has become more and more frequent in recent years.
For example, the extreme heat that suffocated British Columbia in June 2021 was again the result of atmospheric blocking. That year, the town of Lytton broke a tragic absolute heat record of 49.6 degrees Celsius, the highest temperature ever recorded in Canada.