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ARTICLES >> Environment Weather Watch

Weather Watch (October 2012)

Posted by Bestprac on Oct 04 2012

by Susan Carn (Hawker/Blinman Bestprac Group)

A spider has taken up residence in my rain gauge! Its thick web completely covers the top. However, I haven’t needed to evict it as we’ve had no rain for six weeks, and there’s nothing much in sight.

This has meant that we won’t be reaping any crops this year. So why did we decide to sow in the first place? Well, before we sowed (late in May), I did a decision making Matrix which highlighted the following things. First the good:

  • We’d had a very wet summer so sub-soil moisture was good
  • Wheat prices could be on the up
  • We had bought a new (very cheap second hand!) bigger air-seeder that would make for quicker input and, therefore, less diesel used
  • Most Global Seasonal forecast models were saying that SA would be close to average for winter rainfall
  • A weakly negative (and, if not, neutral) Indian Ocean Dipole was expected in Winter/Spring

Then the bad:

So, considering all of this, we decided that the” goods” outweighed the “bads” and decided to sow, but to be conservative and to only sow half of what we normally would.

So what have I learnt from this?

  • In my country, I can’t rely on sub-soil moisture to last.
  • It was worth “having a go” when our input costs were low and prices were up, plus it will do as more sheep feed.

Here is the rainfall Decile chart for SA winter to show what did happen:




As you can see, the global forecast models were correct for the cropping areas of SA as being average, but when I break it down, my June and July were average but August was Decile 1! Followed by less in September which led to dead crops!

The Indian Ocean Dipole, instead of being weakly negative, went strongly positive! Very simply, this meant that waters off the coast of WA went cold, which meant less moisture in the air, which meant no rain bearing north-west cloudbands. This certainly shows up in the map. The IOD is proving to be a force to be reckoned with, and hard to predict its swings.

The Bureau correctly predicted a dry autumn, and a strengthening STR (sub-tropical ridge), which very effectively blocked most of the rain bearing low pressure systems from coming up as far north to me! Hopefully the cropping districts closer to the south coasts have fared better than here.

So can they expect any finishing rain? It looks like there may be a bit of something coming soon. Keep track of rain bearing systems on the BOM Interactive weather and wave forecast map.

I can hear the wind outside as I type – probably a hot north one! You can keep track of wind and its strength and direction on the BOM Water and the Land site.

Here’s a way of hearing the latest updates for SA: On the first Saturday of each month you can hear Darren Ray (Senior Meteorologist/Climatologist SA BOM) speak about the coming seasonal forecast, on ABC Radio’s morning show, as part of the garden section, usually after 9am.

So to all the croppers out there, I hope your crops finish up alright and get good prices! 

Last changed: Oct 05 2012



Good weather analysis By Jane Luckraft on Oct 06 2012
I always enjoy reading Susan\\\'s weather analysis as it is in layman\\\'s terms and makes sense to me. Keep up the good work, Susan.

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