La Niña Is Here / 1st December Update

Australia’s Bureau of Meteorology (BOM) has declared a La Niña weather event is under way in the Pacific, bringing the country in line with other agencies and underscoring the prospect of a relatively cool, damp and stormy summer for much of the north and east.
As if we didn’t already know this!*
It’s been a very wet and cool spring so far.
So what is La Niña?
The atmosphere is full of giant circulations which transport, mix and disperse air and energy around the world.

One of these giant eddies is the Walker Circulation.
The Walker Circulation crosses the Pacific Ocean, rising in the west in the warm waters near Australia, pushing up and over the Pacific and descending near South America before racing back across the Pacific to form the trade winds.
La Niña is the term used to describe when the Walker Circulation is very strong.
The western Pacific is even warmer than usual, the trade winds are stronger and all this moist energetic air is pushed onto Australia.
La Niña is therefore typically associated with wetter than average conditions for northern and eastern Australia, particularly in winter, spring and early summer.
The current model outlooks suggest this La Niña will persist until the late southern hemisphere summer or early autumn 2022.

A full rundown on weather predictions from the BOM for the next 6 months is here.

Update: 1st December 

* NSW has recorded its wettest and coolest November ever with rainfall records spanning more than 100 years tumbling in parts of the state.
The Bureau of Meteorology said overall, the state recorded nearly three times the average November rainfall, breaking a previous record from 1917.