Weather system brews ‘perfect storm’ for abnormally intense heatwave
SOURCE:ABC Australia|BY:Tom Saunders
Southern states continue to sweat through one of the most intense heatwaves on record, and for many regions, including Melbourne and Sydney, the hottest weather is still to come.
A large swathe of the country will again bake through 40-to-45 degrees Celsius heat today, as a scorching north-westerly airstream from the outback strengthens and stretches the hot air mass from northern WA back to the Victorian coast.
With an increase in wind, fire dangers will also escalate during the next 48 hours, reaching "catastrophic" in Victoria and "extreme" in parts of SA and eastern NSW.
The hottest air will then reach the NSW coast tomorrow, resulting in Sydney's hottest weather in up to six years, while a cool southerly change will cause temperatures in SA and Victoria to plummet by as much as 20C in 24 hours.
Temperatures nudge NSW, VIC, SA and WA records
This week's weather pattern is the "perfect storm" for an abnormally intense heatwave, as hot and dry winds from our northern interior combine with sunshine and a mass of sinking hot air from the atmosphere above.
Temperatures have even surpassed forecasts by a few degrees in some locations as maximums skyrocketed up to 19C above the January average on Wednesday, and 18C above on Thursday — resulting in the hottest weather in years for many regions.
Some of the more notable daily highs so far this week include:
Victoria — highest temperature 46.5C in Walpeup.
Melbourne 40.9C on Wednesday — hottest day in six years.
Geelong 43.3C on Wednesday — hottest day in six years
Warrnambool 41.3C on Wednesday — hottest day in seven years
Avalon 43.6C on Wednesday — hottest day in six years
Hopetoun 46.3C on Thursday — hottest day in seven years
Temperatures soared up to 48C in parts of SA on Thursday, 47C in Victoria and 46C in south-west NSW. (ABC News)
SA — highest temperature 48.2C in Wudinna, just 0.2C off an all-time record for the town**.**
Wudinna 48.2C on Thursday — hottest day in seven years
Tarcoola 48.1C on Thursday — hottest day in seven years
Renmark 47.2C on Thursday — hottest day in seven years
Whyalla 47.8C on Thursday — hottest day in seven years
Port Augusta 47.6C on Thursday — hottest day in seven years
NSW — highest temperature 45.9C in Hay
Hay 45.9C on Thursday — hottest day in seven years
Deniliquin 45.4C on Thursday — hottest day in six years
Albury 4.03C on Thursday — hottest day in six years
Bega 40.3C on Thursday –hottest day in seven years
WA — highest temperature 49.0C in Onslow on Wednesday, less than 2C off the Australian record of 50.7C in Onslow in 2022 and Oodnadatta in 1960.
Heatwave, fire danger to peak on Friday in Victoria, inland SA
Cooler southerly winds brought relief yesterday to the southern coastline. However, a swing back to north-westerly winds today across Victoria will carry the heat back to the state's coast, while near record highs continue through inland SA and western NSW.
Most of Melbourne is forecast to hit from 42C to 45C this afternoon, potentially the hottest day in decades for some suburbs.
A hot, strong north-westerly airstream will lead to 45C heat over inland SA, Victoria and south-west NSW on Friday. (ABC News)
A westerly change off the Bight should keep Adelaide in the low-mid-30s, while just 100 kilometres inland, regional parts of SA will suffer their third consecutive day in the mid-40s.
Renmark, for example, is predicted to hit 46C, after highs of 45.5C on Wednesday and 47.3C on Thursday, only 0.1C below the town's all-time January record of 47.4C from 1968 (a December high of 48.6C was observed in 2019)
Across the border, 46C is tipped for Ouyen in the Mallee, less than 3C off the all-time Victorian record, while in south-west NSW 46C is ahead for Balranald.
A bushfire near Longwood, north-east Victoria. (Supplied: Splitters Creek Rural Fire Brigade)
A key difference, however, between yesterday's heat and today is the wind, which will strengthen ahead of a gusty change approaching from the west.
Modelling indicates peak gusts over inland Victoria will peak near 90 kilometres per hour, and possibly above 100km/h from storms, which, when combined with the searing temperatures and humidity down around 10 per cent, will lead to extreme fire danger across the state, touching on catastrophic in the South West, Wimmera, Northern Country and North Central.
When the rating reaches catastrophic, fire behaviour is likely to be unpredictable, uncontrollable and fast, with even well-prepared homes coming under threat.
For SA, peak gusts should also reach around 90km/h, enough for extreme fire danger in several regions.
A pyrocumulonimbus cloud forms over the Mount Lawson fire in north-east Victoria on Thursday afternoon. (Supplied: Pete from Bethanga)
Relief on way for south, NSW braces for Saturday heat
The structure of the heatwave will shift on Saturday as a significant wind change cools Victoria and SA, while the hot north-westerlies shift east to the NSW coast.
Most suburbs of Sydney are forecast to reach 42 to 43C, as much as 16C above the January average.
For many suburbs, Saturday could be the hottest day in years. For example, in the city a top exceeding 42.2C would be the highest in eight years.
For Parramatta, a top above 41.5C will be a six-year high.
An Adelaide beach on Wednesday. (ABC News: Lincoln Rothall)
Winds will also increase across NSW tomorrow, gusting to around 90km/h on the southern ranges, and above 60km/h on the Central Tablelands, and around the Southern Highlands and Southern Tablelands.
This should lift fire dangers to "extreme" levels across Greater Sydney, the Monaro Alpine, ACT and Southern Ranges.
Central West and north-west NSW will also remain comfortably above 40C on Saturday, while the change drops maximums by as much as 15C in the state's south-west.
However, the greatest 24-hour falls will occur in eastern SA and western Victoria, where for some towns, Friday tops in the 40s, will lower to the mid 20s.
For Melbourne, the change is due this evening from about 6pm and the city's heat is likely to drop about 15C in two hours, similar to the welcome relief due to reach Sydney just before midnight on Saturday.
By Sunday, the cooler change will have eroded the heat over southern states. However, much of northern Australia will continue to endure heatwave conditions into next week.