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ARTICLES >> Environment Weather Watch

Weather Watch - October 2011

Posted by Bestprac on Oct 02 2011

by Susan Carn

 

As I write, it’s yet another warm windy day, with only a small chance of any moisture to come my way in the next few weeks. The synoptic charts have the high pressure systems lying in their summer position, and the IOD (Indian Ocean Dipole) has gone rather strongly positive, which further diminishes the likelihood of good rainfall. The SOI (Southern Oscillation Index), although positive, is still a long way from indicting a La Nina as we had last year and early this year.

Our growing season rainfall is now decile 2, whereas this time last year it was 7. Rainfall deciles are based on historical rainfall records and enable us to compare the current season with others, and to determine how often a particular amount of rainfall is likely to occur in a specified period.

Records are first ranked, from lowest to highest, and then split into 10 equally-sized groups. The first group contains the bottom 10% of rainfall records, so is called the first decile range. The highest value in the first decile range is called decile 1. The next 10% of all rainfall records becomes the second decile range, the highest value is decile 2, and so on until the 10th decile range.
Have a look at the Bureau of Meteorology’s webpage on deciles.

How different two years can be! The CSIRO says that Australia has the most variable rainfall of all the agricultural producing countries. Yet we still manage to produce food and fibre regardless!

This week we had a group of agronomists from Iraq to visit. It was a good learning experience for them and us. I was asked to explain, via an interpreter, how I use climate data, from the internet, in our farm decision making. It was actually easier than I thought it would be, as I had to keep it simple and in short manageable chunks for the interpreter! Then while he relayed it to them, I had time to work out what to say next. They were very interested, asked lots of questions and wanted to know if I could set up a website to track their climate forecasts for them! I explained that the drivers of their climate were different from Australia’s, but gave them some clues of where they could start.

The annual rainfall in their part of Iraq is about the same as us (300mm), however most of their rain falls in winter. (Quorn’s winter rainfall seems to be declining, and increasing in summer). Plus they have extremes in temperature far worse than anything here. Ben explained to them how, as we are in a marginal cropping area, we try to keep our input costs as low as possible, and that having an idea of how the year might pan out can be a huge advantage.

The visit was arranged by PIRSA and I’m so glad we agreed to take part, as it was very interesting to meet other people who are trying to farm, not only in a challenging climate, but in a country in political turmoil.

A good website I’ve found recently is FutureWise, which was developed by Grain Growers Limited’s Commercial Services Division, and “It provides rural landholders and other industry stakeholders with information about Australia’s climatic history, current season conditions and long term climate prospects”.

You can tailor the information to your district. For 6, 9, and 12 month rainfall probabilities with accuracy percentages, follow this link.

My district doesn’t look too bad on their map so I hope they’re right!
 

Last changed: Feb 09 2012

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