Seasonal Climate Outlook Message for September to December 2004

The bottom line

Climate Watch 03/08/01

Poor Spring Rain Outlook

Since the start of the month the SOI has remained relatively stationary and as of the 3rd September the 30day average of the SOI is minus 8.0. Daily updates on the SOI are available on (07) 46881439. Or if you want to receive the SOI update by text to your mobile phone, send me an e-mail or call 13 25 23.

Based on the recent pattern of the SOI, it is more likely than not, that spring and early summer will be drier than normal. For September through to the end of November there is a 30 to at best 50% chance of getting above the long term average rainfall across Queensland. Now this doesn't mean there will be no rainfall at all. It simply means that in most years like the current year, below average rainfall is recorded overall for September to November.

Compounding the issue of the current relatively low rainfall probabilities, it is worth noting that sea surface temperatures (SST) in the central Pacific from the international dateline running east towards South America remain warmer than normal (+0.5 to 1.5oC).

While not in a "classic" El Nino sea surface temperature (SST) pattern, our own research has shown that the current SST pattern can in itself reduce winter, spring and potentially, summer rainfall in eastern Australia. Therefore our policy remains to recommend a cautious approach when considering the longer-term outlook this year.

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 For the latest SST maps have a look at www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina or at www.longpaddock.qld.gov.au/ Because rainfall probabilities and median rainfall levels vary between regions, we do suggest referring to AUSTRALIAN RAINMAN for more specific rainfall data for your location.

This forecast doesn't suggest or indicate the potential distribution or expected timing of rainfall over this period. The forecast is for a full 3month period and doesn't suggest that any expected rain will fall evenly across these 3 months.

With the next passage of the MJO due over the coming week or so, it will be very interesting to see if it will trigger much in the terms of useful rain to provide some relief from dry conditions

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 www.apsru.gov.au/mjo/ that will allow anyone interested to track its passage.

For more go to www.longpaddock.qld.gov.au ; www.dpi.qld.gov.au/climate or call us through the DPI&F Call Centre on 132523.

The full story

Rainfall probabilities for September to November (06/09/04)

Based on a "Consistently Near Zero" SOI phase (also know as a "Consistently Neutral" phase) at the end of August, there is a 30 to at best 50% chance of getting above the long term September to November average rainfall across Queensland. Now this doesn't mean there will be no rainfall at all. It simply means that in many years with this pattern for September to November, below average rainfall is recorded overall.

It's also worth remembering that for northern Australia we are still in our "traditional dry season" of July, August and September.

As of the 6th September the 30day average of the SOI is minus 7.4. For there to be an overall improvement in the seasonal outlook for Queensland, it would help if the SOI rose to a "Consistently Positive" pattern for a couple of months at least.

It will be interesting to see what the SOI does over the next few weeks as if it remains in a "Near Zero or Neutral" pattern through to the end of the month there is an increase in the likelihood or chance of getting severe storm activity across the southern half of Queensland and northern New South Wales during summer.

Daily updates on the SOI are available on (07) 46881439. Or if you want to receive the SOI update by text to your mobile phone, send me an e-mail or call 13 25 23.

Other states

Similar to Queensland there is a 30-50% chance of getting above the long-term September to November median rainfall across most of New South Wales, Victoria, Tasmania, South Australia, the Northern Territory and Western Australia. The higher rainfall probabilities can be found along the New South Wales coast, the eastern half of Tasmania and south west Western Australia.

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

Because rainfall probabilities and median rainfall levels vary between regions, we recommend referring to AUSTRALIAN RAINMAN for more specific rainfall data for your location. Otherwise call the DPI Call Centre on 13 25 23 or (07) 3404 6999 for more information.

This forecast doesn't suggest or indicate the potential distribution or expected timing of rainfall over this period. The forecast is for a full 3month period and doesn't suggest that any expected rain will fall evenly across these 3 months.

Points to remember when using probabilities

When using probability based forecast systems it is important to consider the opposite aspect. For example Eidsvold currently has around an 80% chance of getting above 120mm through to the end of November. This also means that there is a 20% chance of NOT getting the 120mm through to the end of November.

Another way of looking at this is that in 8 years out of 10 (or slightly more than three quarters of years) with the current SOI pattern, Eidsvold has received at least 120mm for September to November. Therefore in 2 years out of 10 (or slightly less than one quarter), Eidsvold has gotten less than 120mm for September to November.

The intra-seasonal oscillation (or MJO)

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.

The last passage of the MJO influenced our weather around the end of August/start of September helping trigger some useful rainfall totals especially across southern Queensland. If its current timing remains constant it will next be expected around mid October.

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.

Future ENSO development

Although technically we are not in an El Nino, it is worth noting that sea surface temperatures (SST) in the central Pacific from the international dateline running east towards South America are warmer than normal (+0.5 to 1.5oC). We are describing the current SST pattern as a border line El Nino.

While this is not usually as serious as the more 'classic' El Nino pattern such as occurred between 2002 and 2003, this type of pattern can still have major impact on Queensland rainfall and water supply. As an example, we had a 'borderline El Nino state' in 1992 and 1993, both years producing below average rainfall for large parts of Queensland but not to the extent of the 2002/2003 event.

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/

Wheat Crop Yield Outlook

In what shouldn't be a surprise to anyone, at the end of August, seasonal conditions to date and the updated seasonal rainfall outlook indicated the chances of an above median yielding Queensland wheat crop during the 2004 season are low. Although there was a slight improvement in Queenslands wheat crop yield outlook from last month due to the welcome and timely rainfall especially across the southern half of the state, it was too little too late to provide an overall large improvement in the current wheat yield outlook. Given the overall dry conditions experienced in Queensland during the optimum planting window, the area planted to a winter wheat crop this year is also likely to below normal.

This wheat yield outlook is based on a shire scale. It does not take into account crop area planted and is purely a yield forecast. Nor does not take into account individual property circumstances or the effects and damage from poor crop nutrition, pests, diseases, frosts and distribution of planting rain within a shire.

For more information on the APSRU/DPI&F regional wheat crop outlook contact Andries Potgieter on (07) 46881417 or try www.dpi.qld.gov.au/climate where a full copy the wheat crop outlook can be found.

For detail on farm level crop management strategies for CQ and SQ access www.dpi.qld.gov.au/fieldcrops

Analogue Periods

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 September to November in the following years; 2003, 2001, 1999, 1995, 1992, 1990, 1984, 1980, 1978, 1969, 1968, 1963, 1961, 1959 and 1952 and compare the rainfall recorded with your 'normal' rainfall for September to November.

Information on what rainfall patterns where like for August to October in those years can be found at www.longpaddock.qld.gov.au or in Australian Rainman.

Interesting Internet Sites

I have had a number of requests for my "favourite" weather (as distinct from climate) internet sites. I have listed a few below with a brief description of them. Please note that I make no comment on the quality or accuracy of any of the information presented on these sites.

The Australian Bureau of Meteorology - http://www.bom.gov.au

This site is without a doubt a great source of information that I use regularly. This a comprehensive site containing daily and longer term forecasts for across Australia, the latest synoptic charts and maps, the latest radar and satellite images, historical records and long term averages on rainfall, temperature etc, weather warnings, hydrology and educational information etc. Well worth looking at regularly.

James Cook University Metsat - http://marlin.jcu.edu.au/JCUMetSat/web/metsat.html

This site shows full colour satellite images from the Japanese GMS satellite. Updated daily and provides detailed images of current as well as recent weather events.

US Navy Fleet Numerical Meteorology and Oceanography Centre - https://www.fnmoc.navy.mil/PUBLIC/

This is a US Navy site that provides information on meteorology, oceanography and climatology. It also has links to the latest global satellite images and provides a 6day outlook for a number of countries and regions including Australia. To get to the 6day outlook click on the "Australia N.Z." tag on the right hand side of the page. The click on the "all" tag in the table beside the product label "Previous 12-hr Precipitation Rate [mm/12hr] and Sea Level Pressure [hPa]".

If you use information from any of these sites (or any others) I recommend you take into account the key points listed below.

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, TV or the internet and assume what you heard/saw/read applies to your location.

* Management decisions should never be based entirely on one factor (such as a weather or climate forecast). As always, all factors that could impact of the outcome of a decision (such as soil moisture/type, crop, pasture type/availability, commodity prices, machinery, work force, transport, finance, costs, seasonal outlook etc) should be considered.

* 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). Update the information regularly.

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.