Seasonal Climate Outlook Message for May to August 2005

The bottom line

MJO Currently Crossing Northern Australasian Region Dave McRae 09/05/05

The MJO has started crossing the northern Australasian region (the week of the 9th May) and is currently influencing our weather. Given the on-going dry conditions across most of eastern Australia it will be interesting to see if it helps trigger any relief rain or provides an opportunity for planting winter crops.

As an example of the dry, over the 7-months from October 2004 to April 2000 Dalby recorded 290 mm of rain. This compares to its' long term average for those 7-months of 490 mm, which is a shortfall of 200 mm (or 8 inches in the old scale). This in the lowest 10% of rainfall recorded historically at Dalby for this period.

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) across much of Queensland. For more information on the MJO including its location try www.apsru.gov.au/mjo/ or for more technical blurb try www.bom.gov.au/climate/tropnote/tropnote.shtml

In the mean time based on a 'Rapidly Falling' SOI Phase at the end of April, there is generally less than a 50% chance of getting above median rainfall for May to July across most of Queensland with some areas having as low as a 20 to 30% chance of getting above median rainfall. A notable exception to this pattern in Queensland is for parts of the south east coastal strip and for parts of the far north tropical coast where there is a 60 to 80% chance of getting above median rainfall.

Similar to rainfall probabilities for most of Queensland, across the rest of Australia there is generally less than a 50% chance of getting above median rainfall for May to July with some regions as low as 20%.

It is worth noting that if SOI values remain consistently negative for the rest of this month there will be a further corresponding fall in rainfall probabilities across most of the state irrespective of El Niño development.

As of Monday the 9th May the 30-day average of the SOI is minus 10.0. Daily updates on the SOI are available on (07) 46881439. The latest rainfall probability maps for Queensland, Australia and the world are at www.dpi.qld.gov.au/climate or www.longpaddock.qld.gov.au

Because rainfall probabilities and median rainfall levels vary between regions, we recommend referring to Rainman StreamFlow for more specific information for your location. Otherwise call the DPI Call Centre on 13 25 23 or (07) 3404 6999.

Last updated: 8 May 2005