Europe's deadly heat wave driven by 'Omega block' weather pattern

Europe is currently experiencing a deadly heat wave, a phenomenon scientists attribute to a weather pattern known as an Omega block. This pattern, resembling the Greek letter 'Ω' on weather maps, involves a large, stationary high-pressure system trapped between two low-pressure systems. This structure prevents normal weather progression, causing warm air to stagnate and intensify over affected regions.

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Over the region studied, this heat wave is the most severe ever recorded.

The heat wave has pushed temperatures as much as 18 degrees Celsius above seasonal averages, leading to hundreds of fatalities. In France, at least 40 people have drowned while attempting to cool off in rivers and lakes. The World Weather Attribution group of climate scientists described the current heat wave as the most severe ever recorded in the region.

Omega blocks can persist for weeks, exacerbating the heat and dryness. The suppression of cloud formation offers little respite from the sun. France recorded its highest-ever temperature of 43.8 C, and Germany also broke its national record with a temperature of 41.3 C. Meanwhile, areas within the flanking low-pressure systems have experienced cooler, rainy conditions.

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Because you’ve got this high pressure system sitting there in the centre, you have a very stable and very warm air mass because the heat is moved northward into that area.

Scientists are examining the role of climate change in the increasing frequency and intensity of such extreme weather events. The stability of Omega blocks means that the heat can build up over time, leading to unprecedented temperature highs. The potential for these patterns to become more common globally, including in Canada, raises concerns about future climate impacts.

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Then it builds up over time.