SOI in Near Zero Phase Dave McRae 12/02/07
The monthly value of the SOI for December was minus 5.3 and for January was minus 8.9 placing the SOI in a "Consistently Near Zero" phase.
Based on this SOI phase and historical rainfall records, there is a 40 to 60% chance of getting median rainfall throughout Queensland for February through to the end of April. While the outlook is not as positive as many would like, it is an improvement from much of 2006 and as we are in our summer rainfall season there remains a reasonable chance of getting some useful storm rain.
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 February to April in the following years since 1900; 1900, 1903, 1907, 1909, 1910, 1924, 1925, 1927, 1932, 1936, 1945, 1947, 1948, 1949, 1960, 1965, 1972, 1975, 1979, 1981, 1984, 1985, 1988, 1990, 1991 and 1994. Work out your long term average or median rainfall for February to April and see how many times rainfall was well below, well above or close to average.
For example at Stanthorpe, below average rainfall for February to April in those years was recorded 5 times, close to average rainfall was recorded 14 times with above average rainfall recorded 7 times. Therefore rainfall during February to April at Stanthorpe is more likely to be closer to average than well below or well above average. For more information refer to Rainman StreamFlow.
An MJO event was expected around the middle of February (16th to 20th). However it appears that the expected MJO event will be delayed until later in the month. 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/
Despite some big falls of rain recorded in Queensland during January and February, there is a relatively low chance of getting the long term average sorghum yield on a shire basis for the 2006/07 summer cropping season.
As usual there are some variations between the different cropping regions. For example, throughout southern Queensland and northern NSW there is a below average sorghum crop yield expectation on a shire basis. This compares to central Queensland where sorghum yield expectations are similar to or slightly above that of the long-term average sorghum crop yield expectation.
Widespread rain is still needed to improve the currently poor crop outlook for most of the summer cropping region and improve soil moisture levels for the coming winter cropping season.
The regional sorghum crop outlook is based on the assumption of cropping after a summer fallow and does not take into account effects of poor crop nutrition or damage due to pests, diseases, heat or frosts. For more information on shire sorghum yields contact Andries Potgieter on (07) 4688 1417 or 132523.
El Nino conditions in the Pacific continue to persist although show signs of weakening and becoming less intense. At this stage though we think it is too early to make statements that it is all over and that the drought has ended across eastern Australia.
In terms of the development of climate patterns (such as El Nino and La Nina) late summer and autumn is a key time so we closely monitor what occurs over the next few months. A common feature of an El Nino SST pattern is a later than normal start to the monsoon season (as was the case this year). Its effect (or impact on expected rainfall) is usually less noticeable by mid summer.
The 30day average of the SOI has remained in negative values and as of the 12 February was minus 9.3. At this a time of year that is not really a major concern. However if it doesn't return to more positive values during autumn it would be a warning sign for winter/spring. Daily updates on the SOI are available on (07) 46881439. For more information contact us through the DPI&F Call Centre on 132523 or direct on 07 46881459.