From the ABC 7 Weather team

Waterspouts off Avoca Beach, Australia, on Memorial Day (VIDEO)

May 31, 2011 - 02:12 PM
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Australians on Memorial Day were treated to the scary yet harmless sight of multiple waterspouts drifting off of Avoca Beach, near Sydney. Why aren't spouts as deadly as their landlocked brethren, tornadoes?

Australian vacationers on Memorial Day were treated to the spectral sight of multiple waterspouts drifting off of Avoca Beach, located near Sydney. The ghostly sea twisters were associated with a large storm system that spread flash-flooding fears throughout the region. One TV station reported that the funnels stretched 2,000 feet into the sky before disintegrating near land. (Miss the recent twin waterspouts in Hawaii?)

Waterspouts certainly look threatening, and the National Weather Service urges people to take their destructive potential seriously. The Encyclopedia Britannica mentions that intense spouts have sowed death and despair throughout history, without citing any examples (although the hoary tome does say it’s not possible to disperse a spout by firing a cannonball at it). According to Popular Science, a 1921 waterspout over a mountain lake in Colorado, of all places, grabbed a car of tourists, "lifted it like a shingle, and tossed it over a precipice." This video shows a spout in Australia tearing a roof from a building. A kid died recently in a Hawaiian “water spout,” which on closer inspection is technically a blowhole.

Still, it’s hard to find any accounts of spouts doing really eye-popping carnage like their landlocked brethren, tornadoes. Why is that?

A few reasons, actually. It’s obvious that the vast loneliness of the ocean terrain makes it improbable that many people will encounter waterspouts. Even in areas where spouts are known to frequent – like their most popular hangout off the Florida Keys, where 50 to 500 occur each year – the twisters’ relatively brief lifespan of about 15 minutes reduces the potential for lethal mischief.

The spouts are also much weaker than most tornadoes. Meteorologists actually divide them into two categories based on strength and origin. Fair-weather waterspouts grow during calmer weather, climbing from the surface of an ocean or lake into the clouds. They go through a predictable series of transformations from a dark spot on the water to a “spray ring” to a full-blown funnel cloud. Because there’s no storm to push them around, they tend to harmlessly hover in one place before petering out.

Tornadic waterspouts are the more dangerous variety, being associated with severe thunderstorms and capable of throwing out large hail and head-spinning winds. These spouts progress from cloud to ground and often begin their lives as tornadoes before moving out to sea. They zap the waters with lightning, but perhaps not as much as in tornadoes – one study estimates that only 30 percent of spouts are charged with lightning.

Both kinds are powerful enough to give captains of small vessels the capsizing heebie-jeebies. Compared with the twisters the Midwest has seen this year, though, they’re playing in the junior leagues. The wind speed in a strong waterspout is equivalent to the strength of a weak EF-0 tornado. And because there are no trees, 2x4s or cars to throw around, they can’t do as much damage as a tornado, which racks up its most kills with flying debris.

That’s not to say it’s advisable to go play in a waterspout the next time you see one. Better to watch from afar, like the person in the below video did with yesterday’s Australian spouts. For more good spout footage check out this compilation from NOAA.

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