Unusual Multi-State Storm Triggers Severe Weather Alerts Across Eastern Australia

On Sunday afternoon a broad line of thunderstorms moved across eastern Australia, prompting the Bureau of Meteorology (BoM) to issue a severe thunderstorm warning for Sydney, greater Wollongong and parts of the Blue Mountains, Hawkesbury, Gosford, Wyong and Wollondilly, as well as Wingecarribee. The warning covered an area that also included southern Queensland, western New South Wales, the Australian Capital Territory and eastern Victoria. The system produced hail, damaging winds, flash flooding and power outages, with wind gusts recorded at up to 100 km/h in the central west of New South Wales. Flood warnings were active in eight locations across southern Queensland, and the Mary River downstream of Gympie was forecast to reach major flood levels in Tiaro by Sunday evening and continue into Monday.

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He noted that a high-pressure ridge over the Tasman Sea had been blocking weather fronts for ten days, leading to persistent storms and heavy rain in southern Queensland. A cooler air front advancing from the west on Sunday drew tropical moisture northward, extending the storm line from the Snowy Mountains to the Queensland border. Crock added that the front’s continued push would sustain storm activity through Sunday evening and into Monday, with the final surge expected on Monday.

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• Wind gusts: up to 100 km/h (central west NSW).

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• Flood warnings: eight active across southern Queensland.

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• Recent rainfall: 200 mm to 400 mm recorded in Sunshine Coast areas over the past week, after a dry September.

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• Forecasted temperature trend: night-time temperatures projected to be well above average for most of the country from November to January.

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The BoM’s long-range forecast for November to January indicates above-average rainfall for most of Australia, except the far north and much of Tasmania, while temperatures are expected to be warmer than usual, particularly at night. The agency also highlighted that global heating has raised Australia’s average temperature by about 1.5 °C since 1910. In western Australia, cooler weather is expected to continue on Monday with possible showers in the south-west.

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The storm’s scale and the accompanying flood risk underscore the increasing variability of Australian weather patterns. The combination of a prolonged high-pressure block, a strong cold front and abundant tropical moisture produced a “weather whiplash” that delivered rainfall multiple times the October average in parts of southern Queensland. The BoM’s climate data linking a 1.5 °C rise since 1910 to ongoing warming trends suggests that such extreme multi-state events may become more frequent, influencing future preparedness and infrastructure planning across the region.

The Guardian