I guess the verdict is out - does Australia really rank highly as compared to Tornado Alley and how valid are the assumptions. I was brought up with the assumption that Australia ranked second behind the United States in terms of tornado occurrences. A paper from Evesson
http://www.bom.gov.au/amm/docs/1969/evesson.pdf and also revisited by Minor, Peterson and Lourensz 1979 http://www.bom.gov.au/amm/docs/1980/minor.pdf And also a paper initiated by Clarke in the 1960's make mention of tornado density in Australia. Since then, we have had learned a lot more about tornado meteorology. Note the following paragraph: Australia does not experience the extreme temperature contrasts over short distances which characterise some weather patterns in the United States of America, and partly for this reason severe storms are not generally as frequent or severe as in, say, the Midwest of that country. To take the example of tornadoes: the United States generally has at least 10 tornadoes per year ranked as F4 or F5 on the Fujita scale (see Table below), and therefore capable of producing great destruction, whereas only one storm in Australia's history has (officially) been ranked this high. While it is probable that many more such tornadoes go unnoticed in Australia because of our much lower population density, this is unlikely to explain the difference entirely. Source: http://www.bom.gov.au/lam/climate/levelthree/c20thc/storm.htm
I think it sums up quite well what could be anticipated in this country's tornado climatology. Teamed with many reports of microbursts, the introduction of cameras and video camera technilogy with mobile phones, I think there has been a relatively little change in reports of tornadoes in Australia since!
What are your thoughts?