From the Bureau of Meterology website -- refer the last...

From the Bureau of Meterology website -- refer the last bit:

Weekly Tropical Climate Note

Issued on Tuesday 14 September 2010
La Nia strengthens in the Pacific

The 30-day Southern Oscillation Index (SOI) to 11 September was +25. Contributing pressure anomalies were -0.9 hPa at Darwin and +3.0 hPa at Tahiti. The monthly SOI for August was +19 and the 5-month running mean (centred on June) was +13. The monthly SOI has remained positive since April.

All El Nio-Southern Oscillation (ENSO) indicators exceed La Nia thresholds. Sea surface temperatures (SSTs) have remained cool in the central Pacific. Sub-surface ocean temperatures remain well below average in the central and eastern Pacific, with large areas more than 4 C below normal. The tropical Indian Ocean and Maritime Continent region remain warmer than normal, with areas of SSTs more than 1 C above the long-term average. Easterly trade winds have strengthened in the past two weeks and are now stronger than normal across almost the entire equatorial Pacific. Convection near the dateline continues to be below average.

All computer models surveyed by the Bureau suggest that La Nia conditions will continue through the southern hemisphere spring, with the majority indicating that La Nia conditions will persist into at least early 2011. La Nia periods are usually, but not always, associated with above normal rainfall across northern Australia during the "build up" season (September December).