La Niña rains to stay for months

By AAP with AG Staff 12 January 2011
Reading Time: 2 Minutes Print this page
The La Niña climate system which is responsible for much of the heavy rain in Queensland, is set to continue.

HEAVY RAINS BLAMED ON the La Niña weather phenomenon that have brought death and destruction to Australia’s northeast could stay for months, weather forecasters warn.

After emerging from years of devastating drought and water restrictions in 2009, Queensland enjoyed its wettest spring on record last year, making catchments more likely to overflow when further heavy rains hit.

The Bureau of Meteorology said the wet conditions, which began in earnest in December and have wiped out crops, flooded mining operations and claimed at least 19 lives, could continue until the end of March. “The national outlook for the January to March period favours wetter conditions in the eastern half of New South Wales, southeastern Queensland and western Western Australia,” the bureau said in its latest forecast.

Weather change from La Niña

It says the rainfall is the result of cool conditions in the central equatorial Pacific Ocean associated with the current La Niña – a disruptive weather event associated with rains. “The southeast, roughly one-quarter of Queensland… has about a 60 to 75 per cent likelihood of getting above the median three-month rainfall for January to March,” climatologist Grant Beard confirmed.

Grant says the December-March period was traditionally the wettest of the year for Queensland, known as the Sunshine State, and much of the region had endured record rainfalls in December. Experts said even if subsequent downpours were not extreme, they could cause major problems because catchments and rivers were already full to overflowing.

Undertstanding La Niña

La Niña is characterised by unusually cool ocean temperatures in the eastern equatorial Pacific and has been associated with strong rainfall in Asia and Australia, bitter cold snaps in North America, and drought in South America. It is the counterpart to the El Niño weather pattern, generally associated with drier conditions in Australia.

“The Queensland floods are caused by what is one of the strongest (if not the strongest) La Niña events since our records began in the late 19th century,” said Professor Neville Nicholls, president of the Australian Meteorological and Oceanographic Society.

Whether the flooding was related to global warming was unknown, he added. Forecasters are predicting intense rain and thunderstorms on Tuesday and Wednesday for southeastern Queensland.

“Heavy falls will lead to flash flooding and will worsen existing river flooding,” the bureau said in a warning.