News

Winter has arrived

by
June 07, 2018

Frost on Saturday morning near Mangalore.

Winter is no longer coming, it has arrived; but the Bureau of Meteorology is predicting the unusually warm and dry weather will continue.

The bureau’s outlook suggests a 70 to 80 per cent chance of below-average rainfall for the Murray-Darling Basin, while the rest of the country has a 50 per cent chance of below-average falls.

Temperatures are also likely to be higher, with day and night-time temperatures to have an 80 per cent chance of being higher than average.

The El-Nino-Southern Oscillation and the Indian Ocean Dipole are expected to affect this winter, causing other ‘‘climate drivers’’ to have a larger impact.

‘‘We’re expecting warmer than normal temperatures in the Tasman Sea this winter and associated lower-than-normal air pressure. This would mean a weakening of westerly winds over southern Australia that normally draw cold fronts up from the Southern Ocean,’’ bureau climatologist Jonathan Pollock said.

‘‘As a result of this, we’re expecting to see below-average winter rainfalls for ... northern Victoria.’’

The predictions come on the back of one of the region’s warmest autumns on record and second-warmest summer on record.

Agriculture Victoria agronomist Dale Grey said the bureau’s predictions were out of step with other climate institutes.

‘‘The Japanese model has a drier forecast, as does the BOM, but the rest of the models around the world, models such as (European Centre for Medium-Range Weather Forecasts), the US Bureau, NASA and the UKMO, they’re all predicting a more average season,’’ Mr Grey said.

‘‘Generally I would be expecting a greater consensus. If a dry was going to be happening, I’d be expecting a greater consensus that a dry would be happening.’’

Mr Grey said spring rainfall levels were much more important to the region’s agricultural sector than winter rainfall.

‘‘There is a lot of paddocks that have stored soil moisture. But we need some rainfall in winter so that can join up and the roots can get to the stored moisture at depth,’’ he said.

Mr Grey said soils retained moisture below the surface about 50mm and at the surface down to about 10mm.

For a good season, sufficient rainfall is needed to bridge that gap so plants can push roots through.

Without sufficient rainfall through winter and the following spring, a moisture gap could prove problematic for the region’s farmers.

Mr Grey said rainfall levels were particularly low through May, 25mm to 50mm in most areas, making the bureau’s predictions of a dry winter slightly worrying.

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