Slight improvement in outlook Dave McRae 31/05/07
There has been a marginal improvement in the seasonal outlook throughout most of Queensland. Based on a Near Zero SOI phase at the end of May there is a 50 to 70% chance of getting median rainfall during June to August.
However this should not be interpreted as the automatic start to drought-breaking rains as most of the southern two thirds of Queensland will require several years of good rainfall to fully recover.
Using Bell on the northern Darling Downs as an example, records show that rainfall from November 1999 through to April 2007 (90 months) has been in the driest 10% recorded. During that period Bell has accumulated a rainfall deficiency or shortfall of approximately 1175 mm which is close to twice its long term average of 650 mm.
Current SOI values combined with climate model outputs indicate the continuation of a neutral climate pattern is the most likely outcome. The positive news is that there is also a higher than normal chance of a La Nina climate pattern developing and only a low risk of a return to El Nino conditions throughout 2007.
For there to be a sustained and significant improvement in seasonal conditions and a lift in rainfall probabilities, the development of consistently positive monthly SOI values especially if coupled with a La Nina sea surface temperature pattern would help. The monthly value of the SOI for May was minus 2.8.