Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 2:25 PM GMT on March 29, 2006
Tropical Cyclone Glenda has weakened to Category 3 storm on the Saffir-Simpson scale, with maximum sustained winds of 120 mph and a central pressure estimated at 920 mb by the Australian Bureau of Meteorology. While no longer one of the Southern Hemisphere's most intense tropical cyclones on record, Glenda is still a formidable storm likely to inflict heavy damage to the mining, oil, and gas industries along the Western Australian coast. The storm is expected to make landfall as a major Category 3 storm on the Saffir-Simpson scale Thursday. Fortunately, the region is sparsely populated, and significant upper-level winds associated with the jet stream should act to weaken Glenda just before landfall. Still, a 8 - 12 foot storm surge near and to the left of where the eye makes landfall can be expected. This was the approximate storm surge seen from Cyclone Vance in March 1999, a storm similar in strength and landfall location to Glenda. An impressive satellite animation of Glenda is available from the University of Wisconsin.
Figure 1. Tropical Cyclone Glenda at 6:30 GMT March 29 2006, moving southwest parallel to the Australian coast. This visible light image courtesy of the U.S. Navy.
Was Glenda the strongest tropical cyclone ever in the Southern Hemisphere?
The U.S. Navy estimated a central pressure of 898 mb yesterday for Glenda, which is the second lowest pressure I could find record of for the Southern Hemisphere. However, I doubt that this pressure will be considered official, since the Australian Bureau of Meteorology estimated a much higher minimum pressure of 910 mb. Unfortunately, the Joint Typhoon Warning Center does not make official pressure estimates. The record lowest pressure in the Southern Hemisphere is 879 mb, held by Cyclone Zoe of 2002, a Category 5 storm that affected several small islands in the Solomon chain. Reliable records of Southern Hemisphere cyclones only go back to the 1980s, so it is likely that there were other storms with lower pressures than Glenda in the Southern Hemisphere during the past century. The lowest pressure measured at the surface in a Southern Hemisphere cyclone was 905 mb at North Rankin A gas platform during Cyclone Orson on 22-23 April 1989. Orson had 160 maximum sustatined winds at the time, making it a Category 5 storm.
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