Australia Weather News

A thundery week across south-east Australia will culminate in a band of severe weather sweeping from South Australia to the east coast during the next 48 hours.

The spell of wild weather will be caused by a powerful cold front slamming into a warm and humid northerly airstream — a clash which will generate a combination of rain, gales, dust storms and severe thunderstorms.

The front already triggered severe storms over south-east Western Australia on Wednesday.

It will sweep east through South Australia today, then reach Victoria and New South Wales tomorrow.

In the meantime, a low-pressure system attached to the front will also bring widespread rain to Tasmania, with solid falls also drenching drought-ravaged parts of western Victoria and southern SA.

Gusty winds prompt multiple warnings in SA

Warnings have already been issued for SA today as the low slings the cold front from the western border near sunrise to the state's east by about midnight.

A warm northerly airstream ahead of the front will strengthen rapidly through the morning, leading to raised dust and an extreme fire danger over the state's north, along with wind gusts in excess of 90 kilometres per hour from roughly the Northern Territory border down to a line from about Wudinna to Clare.

The risk of damaging winds will be further enhanced in the afternoon as thunderstorms form on the leading edge of the front, which may filter powerful jet-stream winds to the surface.

The storms could even merge into a squall line over central and eastern SA during the evening, a near linear band of fast-moving thunderstorms which typically stretches hundreds of kilometres.

Squall lines sit one below the supercell in the thunderstorm-severity hierarchy and they are typically associated with a brief burst of strong winds and occasionally heavy rain and hail.

The area at the highest risk of severe storms today is north of Adelaide, but the city could catch the southern edge of the band from the late afternoon onwards.

The odd severe thunderstorm is also possible across western NSW and north-west Victoria today near the eastern periphery of the low's circulation. However, the threat of non-severe storms extends well east to Melbourne and the New England region.

Dangerous thunderstorms on the way for NSW and Victoria

Thunderstorms should become even more intense tomorrow as the front from SA crosses the border and collides with the higher atmospheric moisture which prevails through eastern states in the warmer months.

While a band of rain and storms is likely from the early hours across much of NSW and Victoria, the most dangerous storms will fire up in the afternoon.

In a repeat of Thursday, a gusty squall line should again form as multiple storms merge into a well-organised band.

The squall line should extend around 1,000 kilometres from near the Queensland border to central Victoria, then shift east to the slopes and ranges late in the afternoon, before reaching the NSW coast in the evening.

The greatest threat of severe weather is around lunchtime in Melbourne, mid-to-late afternoon in Canberra and during the evening in Sydney.

While the squall line poses a threat of damaging gusts and heavy rain, the atmosphere looks unstable enough tomorrow to also produce supercell storms.

Supercells are long-lasting, rotating thunderstorms capable of producing destructive winds, giant hail and flash flooding, and are therefore responsible for the vast majority of storm damage in Australia.

The greatest threat of supercells is over the NSW north-west, and central and southern inland, along with north-east Victoria.

Much-needed rain to reach drought-affected SA and south-west Victoria

While storms are raging across the south-east mainland, the system will bring widespread soaking rain to Tasmania, with an average of 10-50 millimetres tipped by modelling through the next 48 hours.

Much of the mainland will also pick up from 10-50mm during the coming days, with falls on the higher end of the range likely around the Alps and through some drought-impacted areas of southern SA and south-west Victoria.

For some towns near the SA-Victorian border, totals in the 24 hours to 9am on Friday could be the highest of 2024, although even 50mm would be insufficient to remove the rain deficits in excess of 150mm so far this year.

The front and low will both head off the east coast late on Friday night, however the tail end of the system will still trigger a few showers and thunderstorms across south-east Queensland on Saturday.