Rare climate event set to impact weather

Rare climate event set to impact weather


Meteorologists say a rare southern hemisphere stratospheric sudden warming event it could impact our September weather.

A sudden stratospheric warming event was responsible for the cold snap that engulfed Chicago earlier in the year.

A sudden stratospheric warming event was responsible for the cold snap that engulfed Chicago earlier in the year.

THE RARE climatic phenomenon known as sudden stratospheric warming (SSW) has occurred over the southern hemisphere in the past week.

An SSW was the catalyst for this year's epic cold snaps in the northern hemisphere, such as the so-called 'Beast from the East' that gripped Great Britain in early 2018 or the polar vortex that hit the US Midwest earlier this year, leading to record low temperatures.

However it is unknown what, if any, impact the SSW event will have on Australian weather, given most of Australia is further north than the mid-latitude nations of the northern hemisphere that copped the brunt of the cold snaps.

Graeme Brittain, Weatherzone meteorologist, said southern hemisphere SSW events were rare.

"There have only been two recorded in the past six decades so there is uncertainty about it will play out," Mr Brittain said.

An SSW occurs when the air temperature raises rapidly in the stratosphere, some 30-40km above the ground.

Mr Brittain said the event could cause cold air normally locked around the Antarctic to push up to more northern latitudes.

Because it is so high above the earth there is some lag time before the SSW impacts on our weather.

Mr Brittain said if it was to have an influence it would likely be in mid-September.

He said it would not necessarily mean Australia was enveloped in an icy spell.

"Depending on how the SSW interacts with other factors, such as the jet stream, it could mean some places are hotter than usual, or there could be a spell of wet and windy weather, it really is variable."

During the Beast From the East cycle, the British Isles and Scandinavia were freezing cold, but further south in southern Europe there was significant rainfall and strong winds.

Arctic SSW events are much more common, occurring approximately six times a decade.

Mr Brittain said it was more likely that land masses further south than Australia, such as Patagonia in South America and New Zealand would be impacted by the SSW, but said it was difficult to make predictions as yet.

"At this stage it appears the polar air will initially move towards South America and from there it could set off systems that influence Australian weather, but we don't know too much yet."

The story Rare climate event set to impact weather first appeared on Farm Online.


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