Seasonal Climate Outlook Message for July to October 2004
The bottom line
SOI in "Rapidly Falling" Phase 05/07/04
Despite the fall in value of the SOI from plus 13.0 at the end of May to minus 13.9 at the end of June, there remains a 50-70% chance of getting at least the long term July to September median rainfall for the southern quarter of Queensland. Rainfall probabilities across the rest of the state though are lower, with only a 30-50% chance of getting at least the long term July to September median rainfall (refer to map).
It's also worth remembering that for northern Australia we are now in our "traditional dry season" of July, August and September. For example Emerald has a long term July to September median rainfall of 54mm, Townsville 29mm, Longreach 27mm, Quilpie 23mm, Mareeba 15mm and Normanton 1mm.
While at times there have been some exceptional rain events in Queensland during July to September, the big well above average falls many people now need are therefore not all that common.
The latest rainfall probability maps for Queensland, Australia and the world are at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au
The 30day average of the SOI as of the 5th July is minus 14.7. If you like to follow the SOI, daily updates are available on (07) 46881439. We are also offering a free 3month trial of a SMS text SOI update. A SMS message will be sent to your mobile twice a week. If you are interested in receiving the SOI update call me on 13 25 23.
When using probability based forecast systems it is important to consider the opposing view. For example, Nebo currently has close to a 30% chance of getting at least its long term July to September median rainfall of 50mm. However, this also means that there is a 70% chance of not getting at least 50mm through to the end of September.
Another way of looking at this is that in 3 years out of 10 (or around one third of years) with the current SOI pattern, Nebo has received at least 50mm for July to September. Therefore in 7 years out of 10 (or a bit over two thirds of years), Nebo has gotten less than 50mm for this period.
Given the intensifying dry conditions across most of Queensland, many producers are waiting for the next passage of the MJO. Unfortunately the last MJO in mid June had little impact on our weather. If its timing remains current it would next be expected around late July.
The MJO is simply a band of low air pressure originating off the east coast of central Africa travelling eastward across the Indian Ocean and northern Australia roughly every 30 to 60 days. Research has shown the MJO to be a useful indicator of the timing of potential rainfall events across much of Queensland.
Given the growing interest in the MJO, and with funding from the DPI&F, GRDC and CRDC we have developed a site http://www.apsru.gov.au/mjo/ that will allow anyone interested to track its passage. Feel free to give me a call through the DPI&F Call centre on 13 25 23 if you have any questions.
The full story
SOI in Rapidly Falling Phase 05/07/04
Despite the fall in value from plus 13.0 at the end of May to minus 13.9 at the end of June, there remains a 50-70% chance of getting at least the long term July to September median rainfall for the southern quarter of Queensland. Rainfall probabilities across the rest of the state though are lower, with only a 30-50% chance of getting at least the long term July to September median rainfall.
It's also worth remembering that for northern Australia we are now in our "traditional dry season" of July, August and September. For example Emerald has a long term July to September median rainfall of 54mm, Nebo 50mm, Townsville 29mm, Longreach 27mm, Quilpie 23mm, Mareeba 15mm and Normanton 1mm.
While at times there have been some exceptional rain events in Queensland during July to September, the big well above average falls many people now need are therefore not all that common. The latest rainfall probability maps for Queensland, Australia and the world are at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au
The 30day average of the SOI as of the 5th July is minus 14.7. If you like to follow the SOI, daily updates are available on (07) 46881439. We are also offering a free 3month trial of a SMS text SOI update. A SMS message will be sent to your mobile twice a week. If you are interested in receiving the SOI update call me on 13 25 23.
When using probability based forecast systems it is important to consider the opposing view. For example, Nebo currently has close to a 30% chance of getting at least its long term July to September median rainfall of 50mm. However, this also means that there is a 70% chance of not getting at least 50mm through to the end of September.
Another way of looking at this is that in 3 years out of 10 (or around one third of years) with the current SOI pattern, Nebo has received at least 50mm for July to September. Therefore in 7 years out of 10 (or a bit over two thirds of years), Nebo has gotten less than 50mm for this period.
Given the intensifying dry conditions across most of Queensland, many producers are waiting for the next passage of the MJO. Unfortunately the last MJO in mid June had little impact on our weather. If its timing remains current it would next be expected around late July.
The MJO is simply a band of low air pressure originating off the east coast of central Africa travelling eastward across the Indian Ocean and northern Australia roughly every 30 to 60 days. Research has shown the MJO to be a useful indicator of the timing of potential rainfall events across much of Queensland.
Given the growing interest in the MJO, and with funding from the DPI&F, GRDC and CRDC we have developed a site http://www.apsru.gov.au/mjo/ that will allow anyone interested to track its passage.
Many people like to follow the relationship between the SOI and rainfall patterns in more detail. To do that have a look at what happened in your area over July to September in the following years; 2003, 2000, 1992, 1990, 1988, 1985, 1984, 1983, 1982, 1965, 1963, 1959, 1949, 1948 and compare the rainfall recorded with your 'normal' rainfall for July to September.
Information on what rainfall patterns where like for July to September in those years can be found at www.longpaddock.qld.gov.au or in Australian Rainman.
According to the Bureau of Meteorology "El Nino Wrap Up" www.bom.gov.au/climate/enso/ (dated 23rd June) the Pacific Ocean remains in a neutral sea surface temperature (SST) pattern and is likely to remain that way for the rest of 2004. The Bureau go on to state that there is nothing in the current observations to suggest the emergence of an El Nino event later this year.
However I would like to highlight, that our policy remains to recommend a cautious approach when considering the longer-term outlook.
Part of the cause I have concern with the longer-term outlook (past 3months) is the recent fall in value of the SOI as well as some strong westerly wind bursts have been recorded in the central Pacific over the last week or so. These westerly wind bursts were most likely triggered by the recent passage of the MJO. Westerly wind bursts in the central Pacific at this time of year can be the trigger for an El Nino event to develop.
While July/August is considered 'late' for an El Nino to develop, it is not unheard of. It's also worth remembering that a 'classic' El Nino sea surface temperature pattern is not required to have an impact of rainfall across eastern Australia.
If sea surface temperatures in the central Pacific (from the international dateline running east towards South America) are warmer than normal (plus 1oC) this in itself can be enough to have an impact on our expected rainfall. For the latest sea surface temperature maps have a look at http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/> or at http://www.longpaddock.qld.gov.au/>
Ocean and coupled ocean/atmosphere forecast models are used to show likely SST development out to 9 months. Of 11 models that forecast out to November, 8 indicate the continuation of a neutral SST pattern including the Bureau run POAMA model, while 3 continue to suggest the potential development of an El Nino (or warm) SST pattern.
While it is a positive that the majority of these models highlight a continuing neutral SST pattern rather than an El Nino, again given current conditions (eg recent fall in the SOI, westerly wind bursts) our policy remains to recommend caution when considering the longer-term outlook.
More details on these models can be found at www.bom.gov.au/climate/ahead/ENSO-summary.shtml
* Key Points To Consider When Using Climate Information
When incorporating climate forecasts into management decisions, it could be worthwhile to consider some of the following general rules of thumb developed from feedback from climate users.
* The first point is to be sure of your source of information and what it is actually suggesting. Do not take a quick grab of information from any source including radio or TV and assume what you heard applies to your location.
* Try to access local information or at least be aware of the long term median for your location so you can correctly interpret the forecast.
* It has also been shown to be useful to do a cost benefit analysis of any decision with a climate risk factor eg What will I gain if I get the desired outcome from this decision? What will I lose if I don't get the desired outcome from this decision? What other cost neutral options do I have if any?
* Do not to take a forecast for a specific period (eg September to November) and expand it out (eg late summer).
An interesting site http://www.cvap.gov.au/mastersoftheclimate/> from the 'Climate Variability In Agriculture' (CVAP) research and development program is well worth looking at. It highlights some case studies on how producers and businesses have used (to varying levels of success) climate and weather information in their decision making processes.
