Thursday, February 3, 2011

Cyclone Yasi: La Nina and record ocean temperatures behind storm

From TheTelegraph

Record ocean temperatures and an intense La Nina weather pattern have helped spawn one of the most powerful cyclones in Australian history.

Cyclone Yasi, a maximum category five storm, is headed for northern Queensland, and is expected to affect a region that is home to more than 400,000 people.

The “monster” cyclone formed in the Pacific Ocean near the island nation of Fiji, which gave Yasi her name.

Alan Sharp, national manager, tropical cyclone warning services, of the Australian Bureau of Meteorology, said the cyclone was the worst Australia had seen for more than a century.
"Yasi is not enormously unusual but it is at the top-end of the scale as far size goes as well as intensity,” he said.
The country’s most deadly cyclone to date hit in March 1899 cyclone, striking a pearling fleet on Cape York Peninsula and killing more than 300 people.
Queensand residents warned to 'get out now' as Cyclone Yasi looms 02 Feb 2011

Mr Sharp said the current La Nina was helping drive the record ocean temperatures around Australia that were helping fuel Cyclone Yasi by providing abundant heat and moisture.
La Nina events historically bring floods and an increase in cyclones during the Australian storm season from November to April.
"We can’t say any particular cyclone is caused by climate change. There has been a slight trend towards more intense storms around the world,” Mr Sharp said, adding it was hard to work out what was natural variability or climate-change related.
Scientists say there is a likely climate change link to the current La Nina through higher sea surface temperatures.
The world’s oceans and atmosphere have steadily warmed over recent decades and that warmth could be providing monsoons and storms with an extra kick.

A major global study in 2010, based on complex computer modelling, found that tropical cyclones will become stronger, with the intensity increasing between 2 and 11 percent by 2100.
And while in some regions, such as the western Pacific and around Australia, the average number of storms might decrease, the number of intense storms in the category 4 and 5 range will increase, along with wind speeds and the amount of rainfall.

Queensland is currently recovering from another extreme weather event.
Record floods swamped the southeast of the state last month, killing 35 people.

Links :
  • BOM : Topical cyclone threat map
  • ABC : Tropical cyclones explained / Map (2010-11 cyclone season)
  • YouTube : Tropical cyclone Yasi (30th Jan, 2011)
  • BBCnews : Australia cyclone Yasi roars into Queensland coast
  • TheGuardian : Will cyclone Yasi push Australia into action on climate?

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