Climate scientists go cold on La Nina

Short term hopes for a La Nina fade

Weather
LA NINA: While climate scientists are sitting on the fence, over a La Nina, Agriculture Victoria agronomist Dale Grey is still feeling upbeat about the coming months.

LA NINA: While climate scientists are sitting on the fence, over a La Nina, Agriculture Victoria agronomist Dale Grey is still feeling upbeat about the coming months.

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World's climate scientists hedge bets on a La Nina.

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The world's climate scientists have become more conservative in their forecasts for wetter conditions for Victoria in the coming months.

Agriculture Victoria seasonal risk agronomist Dale Grey told a webinar, the state's soil moisture probes had reflected drier conditions in the last month.

"Some of those wetter areas are using more water than has been falling from the sky," Mr Grey said.

"We are yet to see any serious increases to soil moisture in the Wimmera as a whole, and the western Mallee."

But he said soil moisture had increased in the north-central, north-east and south of the Great Dividing Range.

DRYING CONDITIONS: The latest information from Victoria's soil moisture probes.

DRYING CONDITIONS: The latest information from Victoria's soil moisture probes.

Bureau of Meteorology figures show that up until June 23, 100-200 millimetres had fallen over the north-west, increasing to 800mm over the Victorian Alps and 300-400mm on Gippsland.

Parts of the north central and central forecast districts received up to double the average January-June rainfall.

Most of the west of the state was sitting on the long-term average but parts of east Gippsland remained dry, receiving lower than average rainfall.

Read more:

The east of the state has recieved welcome rainfall

Victoria gets strong quarterly wet start with more rain on the way

Perfect rains, and more coming

Mr Grey said the majority of the world's 12 weather models were less "bullish" than earlier this year.

"At this stage of the season the majority of the world's 12 weather models are 'sitting on the fence' when it comes to rainfall in the next three months, although three of them are signalling 'wetter' for most parts of Victoria," Mr Grey said.

"Four of the 12 models are suggesting drier in the state's South-West region, while all are split in terms of the possibility of a La Nina this year."

Hopes were fading for a La Nina, at least in the short to medium term, he said.

"It's 0.2 degrees cooler there, back further in the eastern Pacific, than normal, a La Nina is -0.8, so we know we are nowhere near that, at the moment," he said

La Nina typically means increased rainfall across much of Australia, cooler daytime temperatures south of the tropics, a shift in temperature extremes, and decreased frost risk.

"In a nutshell, the Pacific Ocean seems to be losing interest," Mr Grey said.

"It's half interested in being a La Nina but at the moment it's just getting no support from the atmosphere above."

IOD and pressure patterns

Mr Grey said there had been little change, for the last 30 days, in drivers for the Indian Ocean Dipole.

"That's a good sign, we are not wanting to see a cooler trend, that would be setting things up for a positive Indian Ocean Dipole," he said.

"We are right on the threshold there but it is well and truly being driven by warm water, off the coast of Africa."

A positive IOD generaly means there is less moisture than normal, in the atmosphere to the northwest of Australia.

That changes the path of weather systems, coming from the west, resulting in less rainfall and higher than normal temperatures over parts of Australia, during winter and spring.

"If we look at the dipole mode index, its +0.4, the threshold, we are right on the threshold," he said.

"It's been driven by this incredible warmth off Africa and we don't see the classic cold signal, off the coast of Sumatra."

Pressure patterns had dominated Victoria's weather over the last month.

"The movement to a winter-like high pressure pattern occurred much earlier than I have ever seen," Mr Grey said.

"The break in the season happened much earlier than usual.

"The prevailing pattern is northwesterly so everything is disappearing away, nothing is coming into Victoria."

Mr Grey said he was still "feeling okay," about the next six months.

"We have had such a great start, the crops and pastures are growing, we have feed for animals, where we haven't seen it for many years.

"Some of the crops are growing quite quickly, because they were planted early and I think it would be hard to see us falling over into something looking really ordinary.

"If it didn't rain in late winter and early spring, things could rapidly go backwards.

"But given where we sit, right now, the backstop position is pretty good."

Mr Grey said he sensed frustration, among farmers, in the face of glowing forecasts, two months ago.

"Now things have completely gone off the boil.

'At the moment, I am just hoping we come out with an average outcome.

"That would be good, and we can still do that, given the start, and average rainfall from now on."

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