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Another extreme Australian hurricane

By: Dr. Jeff Masters, 4:45 PM GMT on April 23, 2006

Australia's hurricane season continues its parade of unusually intense storms this year with the intensification of Cyclone Monica today into a huge Category 5 storm. The 12 GMT advisory this morning from the Joint Typhoon Warning Center put Monica at 165 mph sustained winds and a 892 mb pressure, making it second most intense hurricane ever recorded in the Southern Hemisphere. The most intense Southern Hemisphere cyclone on record was Cyclone Zoe of 2003, which had a 879 mb pressure. The Australian Bureau of Meteorology puts Monica's pressure at 905 mb, which would make it the fifth strongest cyclone on record. Reliable records of cyclone intensity only go back to the mid-1980s in the Southern Hemisphere, but two of top five strongest hurricanes ever recorded there have occurred this year--Tropical Cyclone Glenda (898 mb) from March, and now Monica. What's really extraordinary about Monica is that she came so late in the season--tropical cyclone season is usually over by late April in the Southern Hemisphere. Monica's formation echoes what happened in the Atlantic last year, with the intensification of Hurricane Wilma to a record 882 mb pressure very late in the hurricane season--October 19. When one adds in the $1 billion in devastation wrought in Queensland by Category 4 Cyclone Larry (915 mb) in March, Australians must feel like residents of hurricane alley in the Atlantic did last year, when three of the six strongest hurricanes on record occurred, causing the most damage ever--what's going on with the weather? However, be reminded that the Northern Hemisphere Pacific Ocean had a very below-normal tropical cyclone season last year, and the Indian Ocean also had below normal activity.

Figure 1. Visible satellite image of Cyclone Monica at peak intensity, 165 mph sustained winds and a 892 mb central pressure. Image taken at 7:30 GMT April 23, 2006 by the GMS satellite. Image courtest of the Navy Research Lab

Monica is expected to track just offshore the sparsely populated north coast of Australia today as it moves slowly westward. Darwin, the most heavily populated city in the region, will begin to feel Monica's wind later today, and a direct hit is possible on Tuesday. Monica should slowly weaken before she gets to Darwin, since much of the circulation will be over land, and the eye will have to cross land as well. Still, Monica could still be a formidable Category 3 or 4 hurricane by then, and a direct hit on Darwin would likely cause severe damage.

Jeff Masters

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