5 August 2008
SST stay neutral
According to the latest ENSO wrap up from the Bureau of Meteorology (www.bom.gov.au) sea surface temperatures (SST) in the Pacific Ocean have stayed within the neutral range have although they continued to warm. Trade winds remain close to average in the central and east Pacific, but have strengthened in the west. Cloudiness near the international date-line remains near normal.
Also the majority of the surveyed ocean/atmosphere forecast models predict a neutral SST pattern persisting in the Pacific through to late winter and spring. Of the five that predict through to the end of 2008, all indicate a continuing neutral SST pattern until at least December. No models forecast a return to La Nina conditions.
Therefore SST's are most likely to remain in a neutral climate pattern with a low risk of a return to El Nino conditions in 2008. However it is worth watching SOI trends and Pacific Ocean SST development over the next couple of months as we approach our spring and summer rainfall seasons.
The strength of the MJO has weakened over the past week, with the signal becoming less coherent and eastward propagation stalling. The MJO signal is expected to remain weak for the next couple of weeks. The relatively weak convective region of the MJO is currently located over far western Pacific, north of the Maritime Continent. Based on its current timing the next MJO induced opportunity for rainfall is likely to be early in September.
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/ http://www.apsru.gov.au/mjo/>
Based on a Consistently Near Zero SOI phase at the end of July there is a 30 to 50% chance of getting median rainfall throughout most of Queensland during July to September. The exception is for the central north of the state where there is a lower 20 to 40% chance of getting median rainfall. The thirty day average as of the 5th August was plus 2.7.
While rainfall probabilities for the north are not as high as the rest of the state it is worth noting that especially for northern Queensland we are in our 'dry season'. Therefore significant or 'drought breaking' rain is not usual during this period regardless of the seasonal outlook.
For more information on sea surface temperature maps, the SOI or rainfall outlook maps look here on www.longpaddock.qld.gov.au . To find more information on rainfall probabilities rainfall figures for your area use Rainman Streamflow. Daily updates on the SOI are available on (07) 46881439.