National Seasonal Rainfall Outlook: probabilities for Spring 2003, issued 19th August 2003

Increased spring rainfall favoured in southwest Australia

The Bureau's spring rainfall outlook shows a moderate swing towards wetter conditions in southwest WA. However odds are near 50:50 for the remainder of the country with no big swings towards a wetter or drier season across any State or Territory.

For the September to November period, the chances of above median rainfall are between 60 and 70% in the southwest corner of WA (see map). So with climate patterns like the current, about 6 or 7 seasons out of 10 are expected to be wetter than average in southwest WA, with about 3 or 4 out of 10 being drier.

probability of exceeding median rainfall - click on the map for a larger version of the map

Outlook confidence is related to the influence of Pacific and Indian Ocean temperatures on seasonal rainfall. During spring, history shows this influence to be strong in northern Cape York Peninsula, and moderate across most of the remaining areas in the eastern half of the continent. A moderate influence is also apparent in southwest WA and northern Tasmania. Elsewhere the influence is weak or very weak so users are urged to exercise caution when applying probabilities in those areas (see background information).

The tropical Indian Ocean is currently warmer than average, whilst the Pacific is showing near normal temperatures. For more detail see the El Niño Wrap-Up. The excess warmth in the Indian Ocean has had the greater influence on the overall pattern of probabilities.

July's value of the Southern Oscillation Index (SOI) was +3, fifteen points above the June value of –12. The approximate SOI for the 30 days ending 16th August was +1.


Click on the map above for a larger version of the map. Use the reload/refresh button to ensure the latest forecast map is displayed.

The following climate meteorologists in the National Climate Centre can be contacted about this outlook: Grant Beard on (03) 9669 4527, Janita Pahalad on (03) 9669 4859, David Jones on (03) 9669 4085, Rob Nash on (03) 9669 4288, Felicity Gamble on (03) 9669 4256.
Regional versions of this media release are available: | Qld | NSW | Vic | Tas | SA | WA | NT |

Regional commentary is available from the Climate and Consultancy Sections in the Bureau's Regional Offices:
Queensland -(07) 3239 8669 or (07) 3239 8666
New South Wales -(02) 9296 1522
Victoria -(03) 9669 4949
Tasmania -(03) 6221 2043
South Australia -(08) 8366 2664
Western Australia -(08) 9263 2222
The Northern Territory -(08) 8920 3813



July 2003 rainfall in historical perspective

May to July 2003 rainfall in historical perspective


Background Information