Seasonal Climate Outlook Message for October to January 2003
The bottom line
SOI Remains Negative (Dated 02/10/02)
The 30day average of the SOI as of the 2nd of October is -7.73.
Based on a "Consistently Negative" SOI phase for September, the chance of above median rainfall for October to December is quite low (20-40%) for most of Queensland.
However for parts of southern and far western Queensland probabilities of above median rainfall for the next 3 months are marginally higher (30-50%).
An El Nino pattern continues to persist in the Pacific Ocean.
The full story
Rainfall Probabilities Relatively Low (Dated 02/10/02)
The 30day average of the SOI as of the 2nd of October is -7.73.
Based on the recent pattern of the SOI, the probability of getting above the long term median rainfall for October to December is quite low (20-40%) for most of Queensland. However for parts of southern and far western Queensland the probability of above median rainfall for the next 3 months is marginally higher at 30-50%.
For example, currently there is a 29% chance of getting above the long term October to December median rainfall of 178mm at Emerald. This compares with a 47% chance of getting above the long term October to December median rainfall of 209mm at Dalby.
As rainfall probabilities and median rainfall levels vary across the state, we recommend regularly referring to Australian Rainman or contacting the DPI Call Centre on 13 25 23 for more specific rainfall data for your location.
As always when dealing with probabilities it is essential to consider the additional information provided. For example currently there is a 32% chance of getting above the long term October to December median rainfall of 125mm at Roma. Therefore there is a 68% chance of not getting the long term October to December median rainfall.
Another way of looking at this is that in approximately one third of years (3 years out of 10) with the current SOI pattern, Roma has received its long term median October to December rainfall. Therefore in around two thirds of years (7 years out of 10) with the current SOI pattern, below median rainfall has been recorded at Roma for the next 3 months.
Based on the shift in value of the SOI from August to September the SOI is now in a "Consistently Negative" phase.
For those readers who like to follow historical patterns more closely, years that have had a "Consistently Negative" SOI phase in August/September include 1997, 1994, 1993, 1987, 1982, 1977, 1976, 1972, 1965, 1957, 1953, 1941, 1940, 1934, 1925, 1923 and 1914. What where the seasonal conditions like for October to December in your area for those years?
For those interested in a temperature forecast for the next three months, the recent SOI pattern shows a high probability (70% to80%) of above normal maximum temperatures for the spring/summer period ahead for most areas of the State.
According to recent reports sourced from the Climate Prediction Centre www.cpc.ncep.noaa.gov in the Unites States and the Bureau of Meteorology www.bom.gov.au an El Nino event is continuing to persist in the Pacific Ocean.
These reports highlight not only the tell tale signs of an El Nino, such as warmer than normal surface and subsurface sea temperatures throughout the central Pacific Ocean, but also a partial breakdown of the pattern of cooler than normal water that has existed off the South American coastline over the last few months.
As well, strong westerly wind bursts (rather than the 'normal' south east trade winds) have been recorded along the equator near the international dateline. Based on previous El Nino events as well as current ocean and atmospheric conditions, it is very likely that this pattern will continue through to Autumn 2003.
Given the existence of an El Nino, the output of the reputable long range ocean and coupled ocean/atmosphere forecast models is of interest. Currently 9 out of 12 surveyed models predict an El Nino SST pattern through to January 2003.
Of the 12 models surveyed, 10 provide a forecast through to April 2003. Currently 4 of these 10 models highlight the possible continuation of warmer then normal sea surface temperatures through to April next year. It is worth noting that while the other 6 models forecast a return to neutral sea surface temperatures, currently none predict the potential development of a La Nina next year.
For more climate related information call the DPI Call Centre on 132523
