Seasonal Climate Outlook Message for January to April 2007
The bottom line
SOI Near Zero. Dave McRae 05/01/07
The monthly value of the SOI for November was minus 0.72 and for December was minus 5.33. The SOI is therefore is in a "Consistently Near Zero" phase.
Based on a "Near Zero" SOI phase and historical rainfall records, there is a 40 to 50% chance of getting median rainfall for January through to the end of March across most of Queensland. While the outlook is not as positive as many would like, there has been a marginal improvement in the seasonal outlook and as Queensland is in its summer rainfall season there is a reasonable chance of getting some useful relief rain.
Information on atmospheric patterns and ocean temperatures in the central Pacific indicate that the El Nino sea surface temperature (SST) pattern that persisted in the Pacific for much of 2006 has become less intense over the last few weeks. At this stage I 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 will closely monitor what occurs during that period.
A common feature of an El Nino SST pattern is a later than normal start to the monsoon season. Its effect (or impact on expected rainfall) is usually less noticeable by mid summer. For more on conditions in the Pacific try the Bureau of Meteorology at www.bom.gov.au/climate/ahead/
The 30day average of the SOI as of the 4th January was minus 1.9. Daily updates on the SOI are available on (07) 46881439 or at www.longpaddock.qld.gov.au
The full story
SOI Near Zero. Dave McRae 08/01/07.
The monthly value of the SOI for November was minus 0.7 and for December was minus 5.3. The SOI is therefore is in a "Consistently Near Zero" phase. The 30day average of the SOI as of the 8th January was minus 1.6. Daily updates on the SOI are available on (07) 46881439 or at http://www.longpaddock.qld.gov.au
Based on a "Near Zero" SOI phase and historical rainfall records, there is a 40 to 50% chance of getting median rainfall for January through to the end of March across most of Queensland. While the outlook is not as positive as many would like, there has been a marginal improvement in the seasonal outlook and as Queensland is in its summer rainfall season there is a reasonable chance of getting some useful relief rain.
When using a climate forecast you should remember that the probability or percent chance of something occurring is just that - a probability. For example if there is a 70% chance of recording more than 100 mm there is also a 30% chance of recording less than 100 mm i.e. 70-30; 30-70. It does not mean that you will get 70% more than 100 mm or 100 mm plus another 70%.
The latest rainfall probability maps are at http://www.dpi.qld.gov.au/climate For more on rainfall probabilities for your location refer to Rainman StreamFlow or contact 132523 or (07) 3404 6999.
Information on atmospheric patterns and ocean temperatures in the central Pacific indicate that the El Nino sea surface temperature (SST) pattern that persisted in the Pacific for much of 2006 has become less intense over the last few weeks. At this stage I 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. Its effect (or impact on expected rainfall) is usually less noticeable by mid summer. For more on conditions in the Pacific try the Bureau of Meteorology at www.bom.gov.au/climate/ahead/
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 January to March in the following years since 1970; 1970, 1972, 1975, 1979, 1980, 1981, 1982, 1984, 1985, 1986, 1988, 1990, 1991, 1993, 1994, and 2006. Work out your long term average or median rainfall for January to March and see how many times rainfall was well below, well above or close to average.
For example at Springsure, below average rainfall for January to March in those years was recorded 4 times, close to average rainfall was recorded 10 times with above average rainfall recorded twice. Therefore rainfall during January to March at Springsure is more likely to be close to average than well below or well above average. For more information refer to Rainman StreamFlow.
Another MJO moved eastward towards northern Australia in late December. Evidence of this included the development of a tropical cyclone off the Western Australian coastline and enhanced convective activity towards the equator. However the monsoonal trough over northern Australia is yet to develop. The current MJO event is expected to have crossed northern Australia by the end of the first week of January.
Based on its current timing of around 35 days another MJO event would be expected across northern Australia in early February. 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/ The Bureau of Meteorology www.bom.gov.au as released another Special Climate Statement which reviews conditions over the last 10 years. It makes interesting reading especially with statements such as: for the last 10 years rainfall has been the lowest on record for a number of locations including Toowoomba, Gayndah and Rockhampton. For example Rockhampton has a long term average rainfall of 818 mm. Average rainfall for the last 10 years is 606 mm which is a deficit of 212 mm per year.
The Bureau of Meteorology has also released the 2006 Annual Climate Statement for Australia and Queensland and they make great reading. Some interesting statements include:
* It the eleventh warmest year since comparable records became available in 1910 * It was Australia's warmest spring season on record * 2006 was wetter and cooler than average over northern Queensland and drier and warmer than average over central and southern Queensland * A number of locations in central and southern Queensland recorded their driest year on record. For example Chinchilla recorded 174 mm (average of 669 mm, previous driest 303 mm in 1922, 117 years of records) and Woodlands recorded 199 mm (average 509 mm, previous driest 208 mm in 1915, 101 years of records). This follows an extended dry period which has affected much of southern and central Queensland over the last 5 to 10 years * The highest rainfall total recorded in Queensland and Australia was Bellenden Ker Top station with 9850 mm (average of 7751 mm).
These reports are available at http://www.bom.gov.au/climate/current/
