Jeff Masters: UPDATE on Queensland floods, January 12, 2011

Extreme flooding continues in Australia


by Jeff Masters, Ph.D., wunderblog, January 12, 2011


Flood-weary Queensland, Australia suffered a new flooding disaster on Monday when freak rains of six inches fell in just 30 minutes near Toowoomba. The resulting flash flood killed twelve people, and 40 are still missing. The flood waters poured into the Brisbane River, causing it to overflow, and significant flooding of low-lying areas in Brisbane, Australia's third largest city with some 2 million people, is expected on Thursday. At least 20,000 homes and businesses are expected to be inundated when the Brisbane River crests at a record 18 feet, according to media reports. The Australian Bureau of Meteorology (BOM) reports that an additional 100+ mm (4") of rain has fallen in the Brisbane area in the 24 hours ending at 9am local time this morning, further adding to the city's flood woes. No further significant rains are forecast in the Brisbane area until next week, though. 


According to the Australian Bureau of Meteorology, this is the most significant flooding event in Australia since at least the 1970s. In 2010, Australia had its wettest spring (September-November) since records began 111 years ago, with some sections of coastal Queensland receiving over 4 feet (1200 mm) of rain. Rainfall in Queensland and all of eastern Australia in December was the greatest on record, and the year 2010 was the rainiest year on record for Queensland. 


Queensland typically has its rainiest years when La Niña events occur, due to the much warmer than average ocean temperatures that occur along the coast. 


The BOM notes,"Previous strong La Niña events, such as those of 1974 and 1955, have also been associated with widespread and severe flooding in eastern Australia. Sea surface temperatures off the Queensland coast in recent months have also been at or near record levels." The BOM's annual summary also reported, "Sea surface temperatures in the Australian region during 2010 were the warmest value on record for the Australian region. Individual high monthly sea surface temperature records were also set during 2010 in March, April, June, September, October, November and December. Along with favourable hemispheric circulation associated with the 2010 La Niña, very warm sea surface temperatures contributed to the record rainfall and very high humidity across eastern Australia during winter and spring." 


Beginning in December, the Queensland floods have killed at least 22, and damage estimates are now as high as $13 billion. Queensland has an area the size of Germany and France combined.


Figure 3. Still frame from a remarkable 6-minute YouTube video showing the sad fate of a row of parked cars when a flash flood in Toowoomba, Queensland, sweeps away dozens of the cars. A note to the wise: Two minutes into the video, we see a man enter the flash flood to save his car. He is successful, but his actions were extremely risky -- most flash flood deaths occur when cars with people inside get swept away. I would not have attempted to save my car in that situation.



Link:  http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1725