What does La Nina mean for fishers, boaters?
Australia is likely to have more rain and cyclones, and be hotter in the north and cooler in the southAustralia’s Bureau of Meteorology has announced that there is a good chance that a La Nina weather event is on the way, and likely to stick around until at least the end of the year. But what does that mean?
La Nina, like its opposite, the El Nino, is something that occurs quite naturally over the Pacific Ocean, which stretches between eastern Australia and South America.
An El Nino’s trade winds travel from west to east, drawing cooler air and moisture away from Australia, and leaving us feeling hotter and drier. In contrast, La Nina’s trade winds travel from east to west, drawing moisture and cooler air over Australia.
According to the Bureau of Meteorology, the temperature of the water at the Australian end of the Pacific Ocean has fallen by 0.8 degrees below average, which is enough to officially trigger a La Nona event.
During a La Nina, Australia can generally expect cooler weather south, and warmer weather north of the tropics, and wetter weather across most of the country for the rest of this year.
The cooler weather in the south is also likely to coincide with longer heatwaves with more humidity when the weather does warm up.
However, how much the La Nina will affect parts of Australia will vary widely. For fishers, it is likely to mean that the waters in northern Australia heat up as warm water is pushed west.
This is bad news for sailors because it also increases the likelihood of tropical cyclones in the region and an earlier onset of the monsoon.
More rain also means an increased likelihood of flooding, particularly in Queensland, with more debris washed down waterways and into the sea where it can pose a danger to boaters.
How much extra rainfall the La Nina brings is wholly dependent on how strong it is. At the moment there’s only a 70 per cent chance of a La Nina mucking about with the weather as Australia heads into summer, too, so there’s still a chance that we won’t see much effect at all.
What’s also needed for a La Nina to have more bite in Australia is a strong Indian Ocean Dipole.
Also known as the Indian Nino, the Indian Ocean Dipole flip-flops between warmer water in the east and colder water in the west.
When the dipole is positive, Australia tends to suffer from drought. However, when it is negative we can expect floods.
That’s because a La Nina pushing wind west combined with a negative Indian Ocean Dipole makes conditions perfect for generating heavier than average rainfall – think the 2010 Queensland and 2011 Victorian floods.
Research shows that the Indian Ocean Dipole has more effect on Australia’s weather than La Nina.
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