As parts of Australia swelter through searing September heat and dangerous fire conditions, the weather bureau has declared a double whammy that could lock in more of the same.
The Bureau of Meteorology has formally declared both an El Nino event in the Pacific Ocean, to Australia’s east, and a positive Indian Ocean Dipole (IOD), to the country’s west.
El Nino events typically deliver drier conditions for much of the country, particularly eastern Australia, as well as above-average temperatures.
A positive IOD often results in less rainfall than average over parts of Australia.
When the two patterns coincide, it can magnify the drying effects.
“Both these climate drivers have a significant influence on the Australian climate, in particular favouring warmer and drier conditions, particularly over spring, but also into early summer,” bureau manager of climate services Karl Braganza said on Tuesday.
“Those conditions are accompanied by an increase in fire danger and extreme heat risk.
“It’s really up to individuals and communities now to prepare for a summer of heat and fire hazards.”
Dr Braganza said conditions were not as bad as they were leading into the catastrophic fires of Australia’s Black Summer, but he also warned things were rapidly drying out after three consecutive years of wet conditions.
“Leading into Black Summer in 2019 … we had years of preceding drought,” he said.
“We do have a wetter landscape out there, (but) it is drying out more rapidly than has occurred in recent years.
“We are already seeing extreme conditions in some parts of the continent, particularly in the duration of heat, so we’ve had an extended period of warm and dry weather to start spring.
“Today, we’ve had catastrophic fire conditions on the south coast of NSW, just to underscore that risk.”
Dr Braganza said Victoria, in particular, tended to dry out under a positive IOD influence in spring.
“That tends to really have an influence on Victoria’s rainfall,” he said.
“Coupled with El Nino, we’d expect to see conditions, probably out to mid-summer for Victoria, looking warm and dry.
“NSW similarly … has a large influence with a positive IOD over the spring. We’re already seeing that extended period of warmth since the start of the month in those two states.”
The declarations coincide with severe weather warnings for swathes of Australia’s southeast, including very hot spring conditions, elevated fire dangers, and strong winds fuelled by an approaching cold front.
Large parts of NSW and eastern Victoria are enduring maximum temperatures 10 to 15 degrees above the September average.
A heatwave warning is in place for the NSW south coast, and a catastrophic fire danger warning is also current for the far south coast.
Damaging winds, driven by a cold front, are compounding the danger.
The front has triggered severe weather warnings for parts of South Australia, Tasmania, Victoria and southern NSW, with the possibility of showers, storms, small hail and snow in some areas.
While that will bring welcome relief from the heat in Victoria and NSW, the front will drive the extreme heat further north into Queensland, with the effects most pronounced there on Thursday.
Fire dangers will also pick up across the state, particularly in the south, with the Channel Country expected to reach extreme fire dangers on Thursday and Friday.
