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ARTICLES >> Environment Weather Watch

Weather Watch (July 2012)

Posted by Bestprac on Jul 03 2012

Recently I attended a tourism meeting where we discussed the pioneering history of the Flinders Ranges. It got me thinking about how the early settlers coped with, and more often didn’t cope with, drought.
 

The 1880’s were years of extreme trial for farmers, with the last two years being influenced by an El Nino. Later the Federation drought from 1895 to 1902 was also influenced by several El Nino years.

Farmers back then had no early warning of impending drought and, I guess, if they made it through one bad year they would pin their hopes on the next year being ok. Unfortunately, more often than not, it wasn’t.

Nowadays we have several advantages. We can get early warning of an impending El Nino many months ahead. In fact new research from climate scientists, Nandini Ramesh and Raghu Murtugudde, reported in the journal “Nature Climate Change”, found that there are signs in the ocean up to 18 months before the peak of an El Nino event.

Having such an early warning gives us plenty of time to make plans on many fronts. Take stocking rates for example: De-stocking early has many advantages including better prices before a market gets flooded, more feed available for remaining stock and it prevents overgrazing. So, by rights, the days of huge choking dust storms blowing away precious top-soil and leaving massive sand drifts should be long gone.

Decisions we make these days can be based on scientific facts, obtained through research and trials, rather than just hope! For example, we now know how an El Nino might affect different parts of Australia. According to the Bureau of Meteorology “during El Niño events, large parts of eastern Australia are typically drier than normal during winter and spring, while southern Australian daytime temperatures tend to be warmer. However, El Niño does not guarantee widespread dry conditions.” 

A “classic” El Nino event lasts from autumn to autumn. The graph below shows that most of the current climate model forecasts agree that the tropical Pacific may approach or exceed El Niño thresholds sometime between mid-winter and spring 2012. 

POAMA monthly mean NINO34

The last El Nino year was 2009. So how did it affect winter/spring rainfall in Australia then?

 BOM 2009 winter/spring rainfall mapYou You can see how the eastern side of Australia had some of the driest areas, typical of an El Nino event. However, we must be cautious using this as a guide to what may happen this year, as we also need to consider what the Indian Ocean is doing. In 2009 the Indian Ocean Dipole (IOD) was neutral.

 
The IOD is currently neutral also. However, about half of the outlooks from POAMA, the Bureau’s climate model, indicate the possibility of a weak positive IOD event developing during winter or spring. “Should a positive IOD event eventuate with an El Niño event, this increases the likelihood of dry conditions over southern Australia”, says the Bureau.
 
So at least we know what we’re up against. At the moment those big high pressure systems are keeping my area very dry and very cold. So like a pioneering woman it’s time for me to collect some wood and start the fire. Some things never change!

 

Last changed: Jul 04 2012

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