Storm Australian Severe Weather Forum
Severe Weather Discussion => General Weather - all topics not current severe weather. => Topic started by: Mike on 01 August 2007, 02:53:07 PM
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A friend of mine recently saw a photo of a severe dust storm and asked me if i knew how it happened. Now having some knowledge of storms but i did not know the answer! Could members please enlighten me on what causes these events?
The example being of someone looking at a photograph of blue sky and this huge dust front converging on a town per se....do storms need to be in the area or is it gust front orientated?
Mike
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They can be associated with a thunderstorm or a line of storms - perhaps a squall line. But you can also get a dust storm from a marked wind change. A vigorous cold front with little precipitation will often be the cause in Australia. You also need a large area where the dust particles can be lifted from.
So yes, either situation is a possible cause.
There is quite a contrast between the real 'dust storm' that looks like a thunderstorm shelf cloud advancing, and the more typical not-so-sudden increase in suspended dust that may end up quite thick after some period of time. I've observed the latter a few times here on the NSW North Coast.
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Famous events that come to mind are Griffith a few years ago and also a more recent example. Nick Moir also chased dust storms at the time - ie areas of raised dust. One important component is the requirement to be in a dry region with sand or dust soil or during a long period of drought. Vegetation is reduced significantly during this period of time and also dams and lakes are at a lower capcity - the result more exposed soils.
But Michael hit the nail on the head that a wedge of wind change be it along a storm front or cold front/trough line will defintely be regions where spectacular dust storms occur. We do have at least one example of the Griffith dust storm even as a submission.
Regards,
Jimmy Deguara
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Speaking of dust storms, I've seen minor dust storms that were kicked up as a result of dry thunderstorms, however generally we have missed out on anything major. I remember one back in 2002, my mother whilst overseas woke up one wintery morning to find a redness outside her window, almost everywhere was covered in this red dust that was blown from Africa into Europe, and my father has been in th 1983 dust storm that hit Melbourne, he had some interesting stuff to tell about that, because he was in the town of Seymour working on racing cars, and this huge wall of dust engulfed the place. Not usually a sight you see unless you are in Alice Springs.
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Cool thanks. My mum has a photo from about 1950 of a dust storm moving toward their house in Adelaide. It is the most awesome thing I've seen in black and white! I must try and get that from down south to post here, it's just huge!
Mike