Climate drivers point to big wet continuing

Gregor Heard
By Gregor Heard
May 11 2022 - 2:30am
BIG WET: Australia's ongoing wet could be set to continue through winter with climate drivers correlated with above average rain likely to be in play.

CLIMATE drivers continue to point towards Australia's big wet continuing into the second half of 2022.

The La Nina event in the Pacific Ocean that has been such a critical factor in the heavy rain over the east coast since last spring remains intact, while there is growing confidence that an Indian Ocean Dipole (IOD) negative event, also correlated with above average rainfall, will develop later this year.

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The Bureau of Meteorology (BOM) this week reported that condition in the Pacific Ocean, tipped to drop back under La Nina thresholds in the autumn, still remain above those levels, having decayed little in the fortnight since the last report.

In fact BOM reported several indicators of La Nina, including tropical Pacific sea surface temperatures, cloudiness near the Date Line, and the Southern Oscillation Index (SOI), have maintained or slightly increased their strength over the past fortnight, although subsurface temperatures have come back close to neutral El Nino-Southern Oscillation (ENSO) levels.

Despite the slow breakdown most climate models surveyed by the Bureau indicate a return to neutral ENSO by the early southern hemisphere winter, however there is the still the scope for the declining La Nina to spark significant rainfall events, such as the one currently passing through Queensland.

Only one of seven models continues La Nina conditions through the southern winter.

However, on the other side of the continent climatologists are saying it is increasingly likely the neutral IOD will develop into an IOD negative over coming months, with strong consistency across a number of models surveyed by BOM.

BOM officials did caution that accuracy in predicting the IOD at this time of year was low, but said the forecast for IOD negative had been by a number of international models.

A negative IOD increases the chances of above average winter-spring rainfall for much of Australia.

When data is analysed it can be a larger driver of rain than La Nina even in parts of eastern Australia, such as north-west Victoria and eastern South Australia.

Meanwhile, as climatologists look to predict medium term weather patterns, a strong band of tropical moisture is dumping heavy rainfall on Queensland before it is tipped to move south into NSW and eastern Victoria.

So far northern and central Queensland has recorded the heaviest rain, with over 180mm over parts of Townsville, 150mm at Charters Towers, 85mm at Clermont and 65mm at Emerald.

The rain is expected to linger over the eastern two thirds of Queensland for much of this week, with inland areas east of Longreach expected to receive substantial falls.

Further south, the unusually the rain is expected to be heaviest over north-west NSW with only relatively light falls in coastal regions.

In Western Australia, virtually all of the state's cropping belt is expected to receive useful falls this week to consolidate the April break.

The Esperance region, which has been relatively dry, is flagged to receive a reasonable fall to help with crop emergence.

Gregor Heard

Gregor Heard

National Grains Industry Reporter

Gregor Heard is Fairfax Ag Media's national grains industry reporter, based in Horsham, Victoria. He has a wealth of knowledge surrounding the cropping sector through his ten years in the role. Prior to that he was with the Fairfax network as a reporter with Stock & Land. Some of the major issues he has reported on during his time with the company include the deregulation of the export wheat market, the introduction of genetically modified crops and the fight to protect growers better from grain trader insolvencies. Still involved with the family farm he is passionate about rural Australia and its people and hopes to use his role to act as an advocate for those involved in the grain sector. Away from work, he is a keen traveller, having spent his long service leave last year in Spain learning the language.

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