00:00Finally, the second time since 1950, La Niña is emerging in the middle of summer.
00:07Thousands of kilometres off Australia's east coast, the water temperature in the central
00:10Pacific Ocean has now dropped around one degree below average.
00:14And that passes the La Niña threshold for the first time since the triple dip event
00:18from 2020 to 2022.
00:20If La Niña conditions prevail for another two months, it officially becomes the fourth
00:24event in five years, a frequency only observed twice previously since 1900.
00:30The cooling of the sea surface increases the difference in water temperature between the
00:34central and the west Pacific, an imbalance which strengthens humid easterly winds blowing
00:39towards Australia, promoting the development of cloud and rain over our longitudes.
00:44However, La Niña typically forms in winter and has its greatest impact in spring, when
00:49national average rainfall increases by 49 per cent.
00:53That figure falls to a 20 per cent boost through the summer and the autumn.
00:57The historical swing to favour rain is also reflected in the Bureau's latest seasonal
01:02outlook – up to an 80 per cent chance of above-medium falls through northern and eastern
01:06parts of the country across the next three months.
01:09But this addition of La Niña could be short-lived.
01:12Long-range modelling currently tips our rainfall will return to normal by the middle of autumn.
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