Weird winter weather points to yet more unstable weather

5 September 2024

Mick Tsikas, writing for The Conversation:

The severe weather rounds out a weird winter across Australia. The nation’s hottest ever winter temperature was recorded when Yampi Sound in Western Australia reached 41.6C on Tuesday. Elsewhere across Australia, winter temperatures have been way above average.

41.6°C? It doesn’t even get that hot in summer, at least where we are on the east coast of Australia. Well, hardly ever. There have been one or two days when highs have pushed into the forties, but that’s usually at the height of summer, and still, is rare.

There’s been some strong winds recently. But the trade winds are common around this time of year, particularly August. The warm weather experienced in parts of Australia last week — in what was still winter — is definitely unusual though. I looked up the Southern Annular Mode (SAM), and found the value had been neutral in second half of August. The SAM is a metric of how close cold weather fronts come to the southern part of the Australian landmass.

A negative SAM value means they reach quite some way inland. Cold fronts bring rain and cooler weather. With SAM values being neutral or positive though, these fronts have not been coming through, which may partly explain why it was so warm. But I think climate change, of course, is the remainder, or most, of the reason.

On one day, temperatures almost reached 30°C during this late winter heatwave, in our part of the world. I truly dread to think what summer will bring…