It’s just what global heating has done to the northern hemisphere's jet stream’. The energy that drives the jet stream comes from the temperature difference between the two air masses it divides. However, the Arctic is warming much faster than the rest of the world, so that difference is shrinking – and with less energy, the jet stream is slowing down. That’s what happened to Texas last week: one of those Rossby waves brought cold Arctic air all the way south – and then stuck for a while. It was all happening in big Rossby loops that had taken over the entire jet stream.

Source: The Star March 02, 2021 04:52 UTC