What Is La Niña And How Will It Impact Australian Weather In 2020?

What Is La Niña And How Will It Impact Australian Weather In 2020?

Just when you started packing up your long pants and jackets in preparation for sweltering Australian Christmas and New Years, the Bureau of Meteorology (BOM) has dropped a major bombshell on us. They’ve announced that La Niña is officially underway, which means Australia could be in for a very wet spring and summer this year.

According to the BOM: “La Niña is the cool phase of the El Niño Southern Oscillation. It is associated with cooler than average sea surface temperatures (SSTs) in the central and eastern tropical Pacific Ocean.”

What Does La Niña Mean For Weather In Australia?

The BOM states that La Niña typically results in above-average spring rainfall for Australia – particularly across eastern, central and northern regions.

It will also likely mean cooler days, more tropical cyclones, and an early onset of the first rains of the wet season across the north.

Speaking to ABC, BOM’s head of climate operations Andrew Watkins said, “we tend to have more cloud and a bit more moisture around to evaporate to keep the air a bit cooler.”

“Conversely at night, when you’ve got the cloud acting like a lid trapping in that heat, it can be a bit warmer,” he explained.

The last time Australia experienced a La Niña event was between 2010 and 2012, resulting in one of our wettest two-year periods on record, according to the BOM

Sadly, this also meant Australians experienced widespread flooding in many parts of the country due to record rainfall. Five of the tropical cyclones that occurred in Australia between 2010 and 2011 were in the severe category, including Tropical Cyclone Yasi, which caused much devastation to far north Queensland. 

The BOM predicts that this year will not see the same intensity as the 2010-2011 La Niña event, “but is still likely to be of moderate strength.”

Despite an increased risk of tropical cyclones and flooding, La Niña means a better outlook when it comes to fire risk in Australia, compared to this time last year

"Last year we went into the spring and summer period with a really strong positive Indian Ocean Dipole event; that was keeping things very dry, particularly in eastern Australia and it also had been very hot,” Dr Watkins told ABC.

"But we can never forget southern Australia will always get dry and hot over summer," he said. "There always will be some bushfires, but hopefully this year we have the conditions in place that we won't see those widespread, long-campaign fires that we did see unfortunately last year."

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