Climate Watch Dave McRae Qld Dept of Primary Industries and Fisheries 22/08/06
The standout feature for Queensland producers of the current sea surface temperature pattern is the warming trend in the key regions of the central Pacific Ocean and a cooling trend surrounding the eastern Australian coastline. Despite some press coverage on this topic the current sea surface temperature pattern has not developed enough for it to be categorised as a classic El Nino.
It is worth noting and as we have stated over the last few months that if this warming trend persists it may have a drying effect on our expected rainfall in spring and early summer. This is regardless of whether it is a 'classic' El Nino or not. For more on conditions in the Pacific try the Bureau of Meteorology at www.bom.gov.au/climate/ahead/
For those interested in cloud seeding as a way of getting some more rain there is an interesting report from CSIRO available at www.cmar.csiro.au/e-print/open/cloud.htm It is a better source of information to quote or believe than some recent media articles on this topic.
The next passage of the MJO could be reasonably expected in early to mid (5-15th) September. By late September the sun will over southern latitudes and stronger MJO signals for the following months can be anticipated. 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
The 30 day average of the SOI has remained in negative values and is minus 15.4 as of the 22nd August.
These negative values have coincided with some strong westerly wind bursts along the equator to the north east of Australia. At this time of year this is of some concern in terms of impact on spring and early summer rainfall. A Consistently Negative SOI phase at the end of the month will see a reduction in rainfall probabilities for September to November.
It will be of no surprise to anyone that as August and September have the lowest average monthly rainfall totals for most locations in Queensland it would be unusual for there to be large falls of rain during those two months. Analysis of climate models or forecasts from other agencies (IRI, ECMWF, UK MET) also indicate that the chance of getting well above average or "drought breaking" rainfall is low.
Daily updates on the SOI are available on (07) 46881439. Rainfall probability maps are available at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au For more information refer to Rainman StreamFlow or contact 132523 or (07) 3404 6999.