THE sizzling extension to summer has been spurred by a breakdown in synoptic weather patterns, but a Southern Ocean front looks like it could be about to offer some respite.
Weatherwatch director Don White said autumn usually brings Southern Ocean cold fronts, moving west to east across the continent, breaking up hot summer air that pools in a ridge of high pressure over central and eastern Australia.
So far this year the slow-moving block of hot air has persisted where it would normally perish, bringing record temperatures and bone-dry soil to much of the inland as the winter sowing window opens.
But a front is developing in the Southern Ocean, to the south west of Western Australia, which is forecast to bring cooler air across the country at the end of the week.
Mr White said neutral conditions usually deliver stable weather punctuated by occasional significant rain events that push rainfall totals towards average levels.
Longer term climate scale indicators, in the Indian Ocean Dipole and the Southern Oscillation Index, point towards neutral patterns persisting over winter.
However, while the Bureau of Meteorology’s climate outlook forecast neutral conditions, it pointed out that rather than guaranteeing average rainfall these conditions indicate a reduced chance of prolonged or widespread very wet, dry, hot, or cold conditions.
Mr White said there were two factors behind the unseasonably hot weather.
“The Southern Ocean fronts have been steering off the south east, allowing the weak ridge of high pressure to dominate.
“The other aspect to it was the monsoon was extremely active in northern Australia in January and February.
“Parts of WA had temperatures into the mid-40s in March, which was unseasonably late.
“As a result the heat engine in the north west of the country had more sunshine than normal.
“So we had a combination of hot air drifting south with nothing coming through to push it away.”
Several models are pointing to a weak El Nino event, which can bring dry hot conditions to eastern Australia, to form by the end of the year.
“If El Nino comes it would be in late spring. There is an increasingly chance, but it is too early to call at this stage,” Mr White said.