Seasonal Climate Outlook Message for December 2005 to March 2006

The bottom line

SOI Fluctuates But Outlook Reasonable

The monthly value of the SOI has continued to fluctuate shifting from plus 11.5 for October to minus 2.2 for November. Based on this shift in value, the SOI is now in a 'Rapidly Falling' phase.

Despite the fall in monthly SOI value, there is a 50 to 70% chance of getting above median rainfall during December to February across most of Queensland. Therefore rainfall is less likely to be below median and more likely to be median to above median.

The full story

SOI Fluctuates Dave McRae Qld DPI&F 01/12/05

The monthly value of the SOI has continued to fluctuate shifting from plus 11.5 for October to minus 2.2 for November. Based on this shift in value, the SOI is now in a 'Rapidly Falling' phase.

Despite the fall in monthly SOI value, there is a 50 to 70% chance of getting above median rainfall during December to February across most of Queensland. Therefore rainfall is less likely to be below median and more likely to be median to above median.

The latest rainfall probability maps are at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au and daily updates on the SOI are available on (07) 46881439. For more on rainfall probabilities, monthly averages or medians for your location refer to Rainman StreamFlow.

Storms have delivered some useful rain in the last couple of months across southern and central Queensland. However due to their patchy nature, areas have missed out on the bigger falls or like most of the south west and north east are still waiting for some relief. Most of Queensland needs much more rain before well above average totals are recorded or before the rain could be called 'drought breaking'.

The next climate induced opportunity for rainfall should occur with the next passage of the MJO. The timing of MJO events has been reasonably consistent since May averaging around 45 days. However the timing of the MJO appears to have extended. Therefore the next active phase should begin across northern Australia around mid December.

The MJO is 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 (but not amounts). For more information try www.apsru.gov.au/mjo/

For those who like to follow the relationship between the SOI and rainfall patterns in more detail have a look at what happened in your area during December to February in the following years; 1904, 1905, 1915, 1923, 1936, 1942, 1949, 1956, 1957, 1974, 1986 and 1989.

For example at Springsure below median rainfall for December to February in those years was recorded three times, close to median rainfall was recorded three times and above median rainfall was recorded six times. Information on what rainfall patterns where like for December to February in those years can be found in Rainman StreamFlow.

According to information from the Bureau of Meteorology "El Niño wrap up" at www.bom.gov.au/ the key indicators of the SOI, trade winds and sea surface temperatures (SST) confirm the persistence of a neutral sea surface temperature and climate pattern in the Pacific. This pattern would therefore be unlikely to change before the end of summer.

In terms of output from 12 surveyed reputable ocean or coupled ocean/atmosphere forecast models, all 12 are showing a continuing neutral SST pattern through to April next year. For more information on conditions in the Pacific try the US Climate Prediction Centre at www.cpc.ncep.noaa.gov/

With the recent media coverage of the UN meeting on global climate change it is worth noting that global average annual surface temperatures are warming. Refer to http://www.bom.gov.au/silo/products/cli_chg/ where graphs and maps of temperature trends since 1900 across Australia are available. Some key points on existing temperature trends are:

Global surface temperatures have increased since 1861 with the rise greatest in the Northern Hemisphere. Similar to the global trend, Australian temperatures have increased (although not consistently).

The average Australian annual surface temperature has increased by 0.76oC with most of that occurring during last 20 years. Australian average minimum temperature has increased by 0.96oC while the Australian average maximum temperature has increased by 0.56oC.

The frequency of extreme warm days and nights has increased while the frequency of extreme cool days and nights has decreased. There has also been a decrease in length of frost season and decrease in the annual number of frost days.

For more information contact the DPI Call Centre on 132523 or (07) 3404 6999.

Last updated: 30 November 2005