True force of Yasi may never be known

By AAP with AG Staff 3 February 2011
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Because there were no gauges where Cyclone Yasi made landfall, there are no direct measures of its strength.

ESTIMATES OF CYCLONE YASI’S most detructive winds are pegged at 290 km/h, but the full force may never be known because there are no gauges where the monster storm made landfall.

Bureau of Meteorology Rick Threlfall says the nearest official weather instrument to Mission Beach, where Yasi crossed just before midnight, was at Lucinda, 120 km south of Mission Beach. The bureau was making educated wind-gust assumptions, he says, although a post-cyclone examination would give an indication of just how destructive Yasi was when it crossed the coast.

“Unless they (cyclones) go right over the station as they cross, which hardly ever happens, they are usually a best estimate,” Rick says. “At the moment it looks like a Category 5 from what we’ve seen so far.”

Cyclone Yasi: winds up to 220km/h

He says the highest “unconfirmed” report made by an an official bureau observer was at Innisfail, and the highest confirmed wind gust was at Lucinda. “An unconfirmed report is a 220 km/h gust at Innisfail,” Rick says. “We need to check to find whether they (the observer) went outside to do this or they may have made the estimate on past experience. We need to check them all out.”

The highest confirmed gust by an automated instrument is from Lucinda which registered 185 km/h. But because there was no instrument in the centre of Yasi itself,  “it’s going to be hard to get exact confirmation of wind strength and that kind of thing,” Rick adds. “Sometimes with severe cyclones we do post-event analysis of damage in the area to determine the strength.”