Seasonal Climate Outlook Message for April to July 2002

The bottom line

Rainfall probabilities remain low for most of Queensland (Dated 04/04/02)

Based on the pattern of the SOI over February/March, there is only a low 20-50% probability of receiving median rainfall for April to June across most of Queensland. This area includes most of the south, south east, west, central and north of the state.

The only exceptions are in the far south west and far north west of the state where probabilities of receiving median rainfall for April to June are marginally higher at 50-70%.

The 30day average of the SOI as of the 4th April is -8.6.

Recent changes in both surface and sub-surface temperatures in the Pacific Ocean support the view of a developing El Nino pattern later this year. However more definitive information will not be available until later in autumn due to the variability that exists in equatorial patterns (especially sea surface temperature patterns) over the next few months. We will continue to closely monitor the situation and provide updated information regularly.

Next update on 10/04/02.

The full story

Rainfall probabilities for April/June remain low (Dated 04/04/02)

Based on the recent pattern of the Southern Oscillation Index (SOI) over February/March, the probability of receiving median rainfall for April to June continues to remain low for much of Queensland. Currently there is only a 20-50% probability of receiving median rainfall for April to June for most of the south, south-east, west, central and north of the state.

However the probability of receiving median rainfall for April to June in the far south west and far north west of the state is marginally higher at around 50-70%.

It is essential to remember that when dealing with probabilities to also consider the additional information that probabilities provide. For example, based on the recent pattern of the SOI there is only a 33% chance of getting the long term April to June median rainfall of 175 mm at Miriam Vale. Therefore there is a 67% chance of not getting the April to June median rainfall.

Another way of looking at this is that in approximately one third of years (approximately 3 years out of 10) with the current SOI pattern has Miriam Vale received it long term median April to June rainfall.

Therefore in around two thirds of years (6-7 years out of 10) with the current SOI pattern below median rainfall has been recorded at Miriam Vale for April to June.

The monthly value of the SOI fell from +7.1 at the end of February to -5.6 at the end of March. Based on this shift in the monthly value of the SOI over February/March, the SOI is now in a 'Rapidly Falling' phase.

For those who like to follow historical patterns more closely years in the past that had a "Rapidly Falling" SOI phase in February/March include 1997,1994, 1991, 1985, 1984, 1981, 1980, 1979, 1977, 1968, 1966, 1961, 1955, 1951, 1918 and 1900. What was the rainfall like for March to May in your area for those years? Details of the rainfall in those years can be found at the 'Long Paddock' internet site www.longpaddock.qld.gov.au or in the Australian Rainman CD.

Recent changes in both surface and sub-surface temperatures in the Pacific Ocean support the view of a developing El Nino pattern later this year. However more definitive information will not be available until later in autumn due to the variability that exists in equatorial patterns (especially sea surface temperature patterns) over the next few months.

As we remain concerned about the potential of an El Niño developing we will continue to monitor the situation and provide updated information regularly. Our strong advice therefore is to closely monitor information on SOI trends and sea surface temperature patterns. A sustained drop in SOI values between March and May would, for example, further substantiate the potential for reduced rainfall in many districts later in the year.

With that point in mind it is very interesting that the 30day average of the SOI as of the 4th April is -8.6.

It should also be noted that we do not have to have an El Niño event to reduce rainfall in Queensland. Warmer than normal sea-surface temperatures in the central equatorial Pacific with a coexisting negative SOI pattern can negatively influence our rainfall patterns without there being an El Niño in existence.

If anyone requires more climate related information contact the DPI Call Centre on 13 25 23. Alternatively try the DPI's climate web site www.dpi.qld.gov.au/climate on which the "Climate Note" can be found. The climate note contains more detailed information including rainfall probability maps, SST information etc. A recorded message with the 30day average of the SOI is also available on 46881439.

Last updated: 3 April 2002