Dry and hot winter on the way according to BOM

There is to be little respite from the dry conditions over winter if Bureau of Meteorology (BOM) long range outlooks are correct.
There is to be little respite from the dry conditions over winter if Bureau of Meteorology (BOM) long range outlooks are correct.

THE BUREAU of Meteorology (BOM) has given little cause for optimism for parched grain growers looking for winter rainfall to replenish bone-dry soils, with most areas below a 30 per cent chance of exceeding median rainfall.

The BOM winter rainfall and temperature outlook, issued on Thursday, said the Bureau’s Predictive Ocean Atmosphere Model for Australia (POAMA) forecasting system was predicting markedly higher odds of drier and hotter conditions across virtually all eastern Australia.

In a cruel twist of fate much of NSW, the state worst impacted by drought at present, has the lowest chance of achieving median rainfall according to the BOM, with much of the state just a 20-25 per cent chance of getting that median figure.

The only cropping area not significantly more likely than not to see a dry winter is in Western Australia, where the majority of the wheatbelt is forecast to see neutral conditions.

Eastern Tasmania is the only location in the country with a statistically significant chance of seeing above average rain.

BOM climatologist Andrew Watkins said the likelihood of a dry winter had firmed in BOM models over the past fortnight.

Dr Watkins said there was no major climatic driver, such as an El Niño or an Indian Ocean Dipole (IOD) positive event that was the major reasoning for the forecast for lower than average rainfall.

“For those major climate drivers there is a very much neutral outlook, which will allow some more local factors to be an influence,” Dr Watkins said.

He said below average pressure over the Tasman Sea is likely to weaken the westerlies that bring rain to southern Australia while a ridge of high pressure will mean that fronts that often deliver rain to southern Australia will slip to the south of the Australian landmass.

He said the accuracy of models at this time of year was reasonable.

“There is some skill around this time, particularly for NSW and Victoria.”

However, in a slight glimmer of hope for grain growers, Dr Watkins said the dry winter pattern was not necessarily the beginning of a dry spring.

“If we had this kind of weather pattern and an El Niño developing I would be very worried, but if El Niño remains neutral the weather patterns that mean frontal rain blows south can actually lead to a pattern of showers coming through in the spring.”

“Some years you think there is a strong likelihood of a dry spring following a dry winter, but given the lack of a big ticket weather event this year that is not the case, we could, at this stage, still see a change in rainfall through the spring.”

The BOM is also forecasting hotter conditions, but Dr Watkins said through the winter months evaporation was not a major problem.

Indeed, he said slightly warmer temperatures may allow what little rain there is to spark pasture growth, given soil temperatures will not be as cold as usual.