Major Phenomenon: The Blob Is Back

Major Phenomenon: The Blob Is Back

Development of this strange anomaly, which scientists call the Blob, began in May but picked up pace in July. A high pressure area has formed in the central North Pacific, which is playing a key role in warming the water bodies.


Why did it form?

Two elements explain its formation: the presence of an anticyclone and a larger phenomenon, the Pacific Decadal Oscillation (or PDO).

A key factor is an anticyclone that has been pervasive in the industry for many weeks. This type of atmospheric context reduces the presence of winds. These churn up the ocean, bringing the deeper, colder water to the surface. Without gusts, the heat is stored faster in the same place. These dynamics are similar to a heat wave on land, except the water is warming.


The other element to consider is the PDO. This phenomenon corresponds to a variation in water temperature in the Pacific Ocean between Canada and Russia. Its cycle oscillates between a negative phase (cold) and a positive phase (hot), often over several decades. The western Pacific is cooler during a warm phase while the east warms, and vice versa during a cold episode. At that time, the ocean would be under the influence of a negative era. Its shape is currently that of a horseshoe: a large warm region surrounded by cooler water. This context may have contributed to the formation of the blob and encouraged its intensity and longevity.


Result: A marine heat wave has formed, which has increased in intensity in recent weeks. We call it the blob. This situation occurs throughout the episode La Niña, well encamped off the coast of Chile.


Good to know : The blob corresponds to a warm water anomaly in the Pacific Ocean off the coast of British Columbia. The largest event of its kind occurred between 2013 and 2016 and caused unusual heat in the north-west of the North American continent. Surface water temperatures remained an average of 2.5°C above normal for 226 consecutive days. The ensuing algal bloom had a significant impact on fisheries and ecosystems in the region.

Potential impact as far north as Quebec

The anticyclone at the blob’s origin may affect the polar jet stream (the one that controls the trajectory of lows and air masses affecting Quebec). This was particularly the case in 2015, when it was blamed for bringing a snowy and cold winter to the eastern part of the Americas, including Quebec, and drought conditions on the west coast. In Montreal, the winters of 2013-14 and 2014-15 were among the coldest on record.


The flow pattern in the Pacific Ocean can therefore affect the weather over very large parts of the territory. An impact on the fall is therefore possible and this up to Quebec. However, it is important to remember that the seasons are shaped by a variety of factors, of which the blob and its accompanying context are just a few examples.

Not to pack

For now, this marine heatwave doesn’t appear to be losing any feathers. On the contrary, it tends to expand in various ways, gaining ground towards the east and north. According to current forecasts, the warm anomaly is expected to remain stable over the next few weeks, reaching up to 5°C in places.

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