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.