Cyclone Yasi bearing down on Australia--TAKE CARE AUSSIE FRIENDS!

Cyclones Anthony (lower left) and Yasi (center)
U.S. Geostationary satellite

Comments added 02/02/2011: The core of Yasi is expected to take four hours to pass over an area, a measure of the size of this cyclone. It will last 3 days, and still be a category 1 storm (winds up to 125 km/hour) when it is 900 km inland. More than 89,000 people in north Queensland have lost power. The storm tide in Townsville is reaching the 3 meter mark, with expected surges of 7 m. For a discussion of the impact of this to Australia's economy, see Businessweek.com. Here is a link to a good NASA Earth Observatory image.

Cyclone Yasi is now a larger-then- Katrina-sized storm bearing down on Queensland's tropical coast, expected to make landfall in the early hours of Thursday a.m. (Australia time; Brisbane is 16 hours ahead me at US Central Daylight Time). It follows on the heels of Cyclone Anthony which left Queensland drenched not long ago. For a set of superpositions like the one below showing Yasi compared to Europe or Asia, go here.
        Yasi is currently over the warm waters of the Coral Sea. These provide energy and water into the cyclone just as the warm waters of the Gulf of Mexico provided fuel for Hurricane Katrina. Here's a good tutorial on tropical cyclones in the Atlantic--just reverse directions for the southern hemisphere!
       Yasi was upgraded to a Category 5 storm at 5:00 am AEDT.  It was about 650 km E-NE of Cairns and 650 km NE of Townsville. It is moving W-SW at 30 km/h. Coastal residents between Port Douglas and Townsville are warned of an "extremely dangerous" storm tide, with flooding inland.  This storm unfortunately is only weeks after the last episode of severe flooding in Queensland. Gusts reaching 280 km/h are expected in some regions in the evening. Unfortunately, the peak of the storm will hit Cairns in the dark, about 10:00 in the evening. The Australian Defence Force has evacuated hundreds of patients from two hospitals in Cairns.

Cyclone Yasi superposed on the USA
http://www.news.com.au/breaking-news/floodrelief
/how-cyclone-yasi-compares-around-the-world/story-fn7ik2te-1225998762870

Trivia: 280 km/h is 77 m/s.  The speed of sound in air is 340 m/s.   These winds would have a Mach number of 0.23, not trivial!!

Projected path of Yasi

Unfortunately, Yasi is going right over Australia's famed Great Barrier Reef.  The projections are for hurricane force winds and sea swells greater than 6 meters.  Coral reefs growing in cyclone areas suffer periodic damage from the waves and storm surges.  They can be broken and wiped out down to a depth of 20 m, with the branching colonies being much more susceptible to breakage than the more massive forms. The reefs can also be damaged by the sheer influx of freshwater from the storms.
        According to the local Cairns news, "Yasi is expected to be Queensland's worst cyclone, covering something approaching twice the physical size of Cyclone Lary, which devastated the Innisfail region in 2006, causing 1.5 billion AD in damages.

For other posts on this blog about the Australian weather, here's "Santa Never Made it into Darwin", and Inland Tsunami. The Santa post has Super Typhoon Tip for comparison to Yasi.

Natural disasters in China, 2010

Mudslide in Zhouqu county,
northwest Gansu province, Aug. 9, 2010
Photo possibly from MSNBC

Today (January 27) China announced the allocation of 1.039 billion yuan ($157 million U.S. Dollars) to areas hit by natural disasters in 2010. This is in addition to 4.1 billion yuan ($617 million U.S. dollars) allocated in November to help the survivors of the disasters get through the winter.  A magnitude 7.1 earthquake hit Yushu killing 2200 people, and a mudslide in Zhouqu left 1700 people dead or missing. There are good posts on the mudslides and floods on Dave Petley's Landslide blog.

It has been estimated by the Disaster Emergency Management in China that natural disasters affect 200 million people every year, and that they are one restricting factor on social and economic development (reference here). These are typically floods and associated landslides, earthquakes and famines.  The deadliest flood, and possibly deadliest natural disaster, of all times were the 1931 floods in China, with estimated deaths ranging from 2,000,000 to 4,000,000.  The 1976 Tangshan earthquake killed between 242,419-779,000 people (I love the number of significant figures in that statistic!).  

Cyclone Tracy and "Santa Never Made it into Darwin"

Source unknown

The current floods in Queensland, Australia, are another in the extremes of fire and water that hit Australia (earlier post here). Cyclone Tracy struck Darwin, Australia, on Christmas Eve and Christmas Day, 1974.  It killed 71 people, destroyed over 70% of the buildings in Darwin, left another 20,000-25,000 people homeless, and caused over $800 Australian 1974 dollars damage. It spurred a priority to develop cyclone-proof buildings. Many of the survivors were evacuated to other towns and never returned to Darwin. The storm was an unusually compact cyclone, with gale-force winds extending less than 50 km from the center; the graphic on the right shows the relative sizes of Tracy (look hard for the small dot in the middle of Texas, right above the T in Tropical) and Super Typhoon Tip.  There's a good Wiki article on Cyclone Tracy here, so I'll not repeat the info.

Relative typhoon sizes.  Public domain, NOAA.

The event was so traumatic for Australians that it made it into the popular media.  Here's a link to a song describing the effects, sung by Bill (Cate) and Boyd (Robinson). It was a fund-raiser for the reconstruction effort.  Sometimes a scientific explanation can't compete!

"Inland tsunami" in Toowoomba, Queensland, Australia; floods in Brazil; Sri Lanka

AP photo from here

More than 375 people are reported dead in floods and landslides in Brazil (note added on 1/17/11: over 600 deaths now reported). A million are reported homeless due to floods in Sri Lanka. Major floods have been occurring in Australia, building up for several months and culminating last night with the flooding of Brisbane, Australia's third-largest city. In spite of individual stories of courage and heroism, there have been at least 34 deaths there. The National Post in Canada reports "Horrific picture emerges of Australia flash floods", and that Brisbane resembled a "war zone" as the flood hit 30,000 properties.

Here and here are two excellent and scary videos of the Toowoomba flood:

The water rose so quickly in Toowoomba that the event has been described as an "inland tsumani".     Perhaps this poem--one verse from a nineteenth century Queensland droving ballad, "The Overlander"  about northern Queenslan--summarizes the setting:

"I come from the northern plains

Where girls and grass are scanty;

Where the creeks run dry or ten feet high,

And it's either drought or plenty."

The whole ballad is sung on this video.

A discussion of the role of La Nina and the North Atlantic Oscillation in these weather events is here. Although there is much speculation on the WWW about the role or implications of these events and climate change, there are also lessons to be learned by looking back 150 years at the history of this part of Queensland.  It is tragically like many, many other places in the world where humans have altered their landscapes. I excerpt the following history from this reference.

For more than a century, the Queensland government had a vision, and determination, to introduce farming into this region. Australian history in the 1800's is complex.  Queensland became an independent state in 1850, with a complex history of replacing pastoralism with farming and dairying--dairying being needed to sustain the farmers until crops were sold, or in case they failed.  In the 1887 a Department of Agriculture was established in Queensland, and by World War One, the region around Toowoomba was exporting grain.

In order to meet the demand for fencing, an enormous number of trees were felled, depleting the forest resource.  Reserves and parks were established in the headwaters, but tree-clearing and increasing stock numbers caused erosion on ridges and compaction of vegetation on floodplains. In the 1870's and 180's, residents of Toowoomba changed the forest into orchards, which caused the water table to rise and swamps to developed.  Drainage became a problem, and mixing of raw sewage and groundwater wells resulted in a series of typhoid epidemics in the 1870's and 1880's. This was corrected by civil engineering and introduction of sewage systems.

However, as has been observed around the world, the replacement of vegetation with urban roads and buildings increased the rate of runoff to the main river channels. Flash flooding became a common experience in the main towns. Thus, more than a century of history preceded the tragedy of this week.

More on flash flood dynamics in a later post.