Seasonal Climate Outlook Message for January to April 2004
The bottom line
SOI In Rapidly Rising Phase 07/01/04
The 30day average of the SOI has remained in positive values since the start of the month and as of the 7th January is plus 5.8.
However, the recent rise in SOI values has had only slight effects on rainfall prospects for Queensland. Highest rainfall probability values now exist in the northern tropics and in western border areas. In these areas there is a 60% to 70% chance of getting above the long term January to March median rainfall.
For most of the rest of Queensland, forecast conditions remain mixed with a 50/50 chance of receiving above median rainfall for January to March. The lowest rainfall probabilities can be found in the far south west of the state where there is only a 20-40% chance of getting above median rain. For example Thargomindah has a 29% chance of getting above its long term January to March median rainfall of 85mm.
For more information contact us through the DPI Call Centre on 13 25 23.
The full story
Climate Watch 06/01/04
The SOI rose in value from the end of November (minus 2.4) through to the end of December (plus 9). Based on this shift in value the SOI is now in a "Rapidly Rising" phase.
However the rise in SOI values has had only slight effects on rainfall prospects for Queensland. Highest rainfall probability values now exist in the northern tropics and in central western border areas. In these areas there is now a 60% to 70% chance of exceeding median rainfall for the January to March period 2004.
For most of the rest of Queensland, forecast conditions remain mixed with a 50/50 chance of receiving above median rainfall for January to March. The lowest rainfall probabilities can be found in the far south west of the state where there is only a 20-40% chance of getting above median rain. For example Thargomindah has a 29% chance of getting above its long term January to March median rainfall of 85mm.
It's worth remembering that this forecast does not suggest or indicate the potential distribution or expected timing of rainfall over this period. The forecast is for the full 3 month period and does not suggest that expected rain will fall evenly across these 3 months.
When using probabilities or a percentage chance of something occurring (eg amounts of rain in a 3 months or a race horse winning), it is important to consider the opposing view. For example, while Thargomindah has a 29% chance of getting above its long term January to March median rainfall of 85mm this also means that there is a 71% chance of not getting above 85mm.
Another way of looking at this is that in 3 years out of 10 (or around one thirds of years) with the current SOI pattern, Thargomindah has received more than 85mm for January to March. Therefore in 7 years out of 10 (or around two thirds), Thargomindah has gotten less than 85mm for this period.
The latest rainfall probability maps can be found at www.dpi.qld.gov.au/climate or at www.longpaddock.qld.gov.au
As many people like to follow the historical SOI/rainfall patterns more closely, it can be useful to find out what rainfall and farming conditions where like in your area for January to March in the following years - 1998, 1997, 1966, 1957, 1955, 1950, 1946, 1945, 1943 and 1940. Information on what rainfall patterns where like in January to March in those years can be found in Australian Rainman.
The last passage of the MJO influenced our weather in late December. It helped produce some useful but patchy rainfall mainly across eastern Queensland (with much of south west and central Queensland missing out). If it's timing remains current it would next be expected in late January/early February. It will be very interesting to see what effect the MJO will have when it is next expected. Research has shown that in summer the MJO can intensify the monsoon season as well as help trigger cyclones if there are any existing low-pressure systems in the Coral Sea.
The 30day average of the SOI has remained in positive values and as of the 7th January is plus 5.8. If you like to follow the fluctuations of the SOI, daily updates are available on (07) 46881439.
The latest information sourced from the United States Climate Prediction Centre www.cpc.ncep.noaa.gov/ and the Australian Bureau of Meteorology www.bom.gov.au/ highlight that a neutral sea temperature pattern continues to persist in the tropical Pacific Ocean.
However, continuing re-warming of sea surface temperatures in the central Pacific and the return of strong westerly wind bursts to this region have highlighted the potential for 'El Nino-like' conditions to develop next winter if these trends continue for the next few months.
As this is still some time away and conditions can change, we will monitor patterns along the equator in the Pacific on a monthly basis to determine what impact, if any, ongoing changes may have on the seasonal outlook.
Ocean and coupled ocean/atmosphere forecast models (GCM's) are useful tools in giving an indication as to likely ENSO development out to 9 months. Of 11 models that forecast out to May 2004, 8 indicate the continuation of a neutral sea surface temperature pattern while 3 suggest the potential development of an El Nino (or warm) sea surface temperature pattern.
Of the 9 models that forecast out to August 2004, 4 indicate a continuing neutral sea temperature pattern while 5 suggest the potential development of an El Nino pattern.
While it remains positive that around half of these models highlight a continuing neutral SST pattern (rather than the El Nino pattern), given current ocean and atmospheric conditions our policy remains to recommend a cautious approach when considering the longer term (6-9months) outlook. More details can be found at www.bom.gov.au/climate/ahead/ENSO-summary.shtml
One point that can be raised from the GCM outputs is that none of the models are showing the potential development of a La Nina. A La Nina sea surface temperature pattern would provide us with our best opportunity for those widespread well above average rainfall events most producers, rural industries and local councils etc are looking for.
As part of the DPIs' response to these changes we have initiated an "El Nino watch" and will regularly monitor any developments in the Pacific and pass on this information on as it becomes relevant.
Although the key period for the development of an El Nino event is still some time away, it could be useful for businesses that are adversely affected by these events to consider now what risk management strategies they could incorporate into their management plans if the likelihood of an El Nino event increases.
For more information contact us through the DPI Call Centre on 13 25 23.
