Risk of late-season frosts this spring

Risk of late-season frosts this spring


Weather
The Bureau has predicted there is still potential for frosts in susceptible areas with an increased risk of late-season frosts this spring.

The Bureau has predicted there is still potential for frosts in susceptible areas with an increased risk of late-season frosts this spring.

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The outlook for spring, released on Thursday, August 15, shows no strong push towards a wetter or drier season ahead for southern Victoria.

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The outlook for spring, released on Thursday, August 15, shows no strong push towards a wetter or drier season ahead for southern Victoria.

At the same time, both maximum and minimum temperatures have roughly equal chances of being warmer than usual.

It's a change from the dry and warm outlooks the Bureau's been issuing for most of 2019, but for northern Victoria, spring 2019 is still likely to be drier than normal.

So, what's "normal" for spring?

From 1990 to 2012, the average spring rainfall for the north-west was less than 100 millimetres.

Central parts of western Victoria averaged between 100-200mm.

Lower parts of the north-east, East Gippsland and exposed parts of the south averaged more than 200mm.

And elevated parts of the Victorian Alps averaged more than 300mm.

But recently we've seen large variability in spring rainfall from year to year.

Spring 2018 was drier than average, especially in the west; overall it was the ninth driest spring in 118 years of record.

In contrast, spring 2016 was much wetter than usual, particularly for the west, ranking as Victoria's 10th wettest spring.

And that followed spring 2015, Victoria's fifth driest spring overall, and the driest spring on record for parts of southern Victoria.

The outlook for spring 2019 is being influenced by the current state of the oceans surrounding us.

The El Nino-Southern Oscillation (ENSO) in the Pacific is neutral, but sea surface temperature patterns in the Indian Ocean are likely to remain the key influence on Australia's climate for the coming months.

The broader Indian Ocean sea surface temperature, cloud and wind patterns have been consistent with a positive Indian Ocean Dipole (IOD) since late May.

Climate models forecast the positive IOD will last through spring. Typically, a positive IOD brings below average winter-spring rainfall to southern and central Australia, and above average daytime temperatures for the southern two-thirds of Australia.

The forecast for drier than average conditions means more cloud-free nights than average are likely, coupled with dry soils in parts of the east and northwest, and there is still potential for frosts in susceptible areas with an increased risk of late-season frosts this spring.

See the complete spring outlook at bom.gov.au/climate/outlooks and make sure to check out the video.

- Jonathan Pollock is a climatologist with the Bureau of Meteorology

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