Weather Experts: Northern and Western Australia to Have A Wetter Season Due to Repeating La Nina
The Bureau of Meteorology said the national weather outlook for February to April this year is that northern and western Australia will likely experience a wetter season, while parts of southeast SA and western NSW will be relatively drier.
The Australian weather agency said this outlook is associated with La Nina, as seen by the warmer than normal Indian Ocean and the cooler conditions in the Pacific.
NASA has also said sea surface height data from its Jason-1 and -2 satellites show that the milder repeat of last year's strong La Niña has intensified. This has increased the odds that the Pacific Northwest will have more stormy weather, while the southwestern and southern parts will be dry, NASA said.
La Niña episodes change global weather patterns and are associated with less moisture in the air over cooler ocean waters. The "diva of drought," results in less rain along the coasts of North and South America and along the equator, and more rain in the far Western Pacific.
According to the Bureau of Meteorology, for February to April, the chances of receiving above median rainfall are above 60% over the tropical north of Australia and western WA, while probabilities increase to 70 and 75% over parts of western WA, particularly the Gascoyne region.
Conversely, the chances of receiving above normal rainfall are between 35 and 40% over southeast SA, the far southwest of Queensland and far western of NSW, the Bureau said, while the chances of below normal rainfall is between 60 and 65%. Over the rest of the country, the chances of a drier or wetter February to April are roughly equal, it added.
Meanwhile, the Bureau of Meteorology has confirmed 2011 was Australia's third-wettest year on record and the wettest year since 1970. The agency's climate monitoring manager Dr Karl Braganza says the rainfall was largely due to the influence of La Nina.
"Typically when you get a really strong La Nina event, and that's measured by these hemispheric indicators across the Pacific, you almost always find flooding across northern and eastern Australia during those big events and at least one big tropical cyclone comes through," Dr. Braganza said.
The wet La Nina is expected to last until autumn this year, when the Pacific Ocean resets and a new weather pattern begins.