Bureau of Meteorology says two climate patterns behind the dangerous fire conditions have shifted towards neutral

This article is more than 8 months old

This article is more than 8 months old

Two climate patterns that have been influencing Australia’s ongoing drought, deadly bushfire weather and record-breaking heat have shifted towards neutral, according to the Bureau of Meteorology.

The changes should reduce the chances of hot winds from the west that have been adding to the extreme risk of bushfires in the south-east.

But Dr Andrew Watkins, the head of long-range forecasts at the bureau, told Guardian Australia the damage caused by the two patterns – the positive phase of the Indian Ocean Dipole (IOD) and a negative Southern Annular Mode (SAM) – would likely remain for several months.

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He said the change in SAM towards more neutral conditions would reduce the chance of westerly winds that had brought heat and dangerous fire conditions.

“We can’t rule the westerlies out of course, but at least the odds of more bad fire weather starts to reduce,” he said.

On Monday, the IOD dropped into neutral from a phase that sees cooler ocean temperatures off the north-west of Australia, causing moisture to be drawn away from the continent.

But Watkins said: “The damage from the positive IOD and the negative SAM has been done – the landscape is extremely dry. This means that fire danger will remain high for some time.

“And it certainly does not mean the end of the drought – that will take some time; many months, especially for those rivers to rise again and for the soils to even reach average wetness.”

Watkins said the IOD had been acting “like a wall” and blocking a separate system that delivers monsoon rains to northern Australia. Weakening trade winds also meant the monsoon had a greater chance of forming and moving over northern Australia.

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“If you have a look at northern Australia – even just Darwin – it’s been very hot and dry. Much hotter than a normal buildup,” he said.

“Darwin has had well over 20 days above 35C this month when its record is nine. They are desperate to see rain.”

The bureau’s models had already accounted for the retreat of both the SAM and IOD in its longer term rainfall outlooks for January and beyond, Watkins said.

The bureau’s climate experts have said the IOD and the SAM have combined with climate change to deliver Australia’s recent run of record-breaking heat.

Australia recorded its hottest day on record on 18 December, with an average maximum temperature of 41.9C (107.4F), beating the previous record by 1C that had been set the previous day.

Rainfall across most of the continent has been well below average in 2019.

Spring 2019 was the driest and second-hottest on record, and also the worst on record for dangerous bushfire weather.