La Nina helps fuel monster cyclone Yasi

David Fogarty Reuters 2 Feb 11;

SINGAPORE, Feb 2 (Reuters) - Record ocean temperatures and an intense La Nina weather pattern have helped spawn one of the most powerful cyclones in Australia but whether there's a direct climate change link is less clear.

Cyclone Yasi, a maximum category 5 storm, was within hours of making landfall in far northern Queensland state and zeroing in on urban centres where more than 400,000 people live.

If it maintained its current intensity when it crossed the coast, it would be the strongest cyclone to hit Queensland since 1899, said Alan Sharp, national manager, tropical cyclone warning services, of the Australian Bureau of Meteorology.

The March 1899 cyclone struck a pearling fleet in Bathurst Bay on Cape York Peninsula, killing more than 300 people in Australia's deadliest storm.

"Yasi is not enormously unusual but it is at the top-end of the scale as far size goes as well as intensity," Sharp told Reuters from Melbourne on Wednesday.



Sharp said the current La Nina was helping drive the record ocean temperatures around Australia that were helping fuel 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," Sharp said, adding it was hard to figure 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.

Yasi, though, isn't the only monster cyclone to menace Australia.

Cyclone Tracy wiped out much of the city of Darwin on Christmas Day 1974, killing 71 people. The anemometer at Darwin airport recorded a gust of 217 kilometres per hour (135 miles per hour) before the instrument was destroyed, according to the Bureau of Meteorology.

Cyclone Larry ravaged the northern Queensland town of Innisfail in March 2006, becoming Australia's second costliest storm after Tracy.

Weeks later, Cyclone Monica became one of the most intense cyclones ever recorded as it moved just off the coast of the Northern Territory, sparing major townships.

Cyclone George in March 2007 was a large category 5 storm that struck near Port Hedland in northwest Western Australia state, causing three deaths and widespread flooding.

Cyclone Olivia in April 1996 generated a wind gust of 408 km/h on Barrow Island off the Western Australian coast -- a world record.

(Editing by Nick Macfie)

Yasi forecast to be most powerful cyclone to hit Australia
Reuters 1 Feb 11;

SYDNEY, Feb 2 (Reuters) - Cyclone Yasi, which is approaching the coast of northeast Australia, is forecast to be the most powerful cyclone to hit the country ever, Sky TV cited the country's weather bureau as saying.

Yasi, which has been upgraded to a maximum-strength category five storm, is about 650 km (404 miles) off the coast of northeastern Australia and is expected to make landfall at 10 pm local time (1200 GMT) on the Queensland coast between Cairns and Innisfail. (Reporting by Ed Davies; Editing by Gyles Beckford)

Yasi not the only monster storm to hit Australia
David Fogarty Reuters 2 Feb 11;

SINGAPORE, Feb 2 (Reuters) - Cyclone Yasi is the strongest storm to threaten Australia in living memory, but the country has long record of powerful cyclones causing death and destruction.

Only Australia's relatively sparse population along much of its northern coastline has limited the damage in the past. But booming mining communities, ports, agriculture and tourism businesses mean more property in the path of storms.

Scientists say Yasi's size and strength is being fed by historically high sea surface temperatures that are providing fuel and moisture to power the storm.

The region is also in the grip of one of the strongest La Nina weather patterns that historically bring floods and an increase in cyclones during the Australian storm season from November to April.

Yasi's current strength is similar to Hurricane Katrina, which reached maximum category 5 in the U.S. Gulf before weakening a little as it made landfall near New Orleans, triggering a massive sea surge that flooded the city.

Forecasters are also expecting a large storm surge to hit the northern Queensland coast.

In the recent past, a number of powerful cyclones storms have hit Australia.

Cyclone Tracy wiped out much of the city of Darwin on Christmas Day 1974, killing 71 people. The anemometer at Darwin airport recorded a gust of 217 km/h before the instrument was destroyed, according to the Australian Bureau of Meteorology.

Cyclone Larry ravaged the northern Queensland town of Innisfail in March 2006, becoming Australia's second costliest storm after Tracy.

Weeks later, Cyclone Monica became one of the most intense cyclones ever recorded as it moved just off the coast of the Northern Territory, sparing major townships.

Cyclone George in March 2007 was a large category 5 storm that struck near Port Hedland in northwest Western Australia state, causing three deaths and widespread flooding.

Cyclone Olivia in April 1996 generated a wind gust of 408 kph (255 miles per hour) on Barrow Island off the Western Australian coast -- a world record.

Scientists can't yet say if cyclones are becoming more powerful because of global warming.

But 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. (Editing by Nick Macfie)