All climate indicators of ENSO remain beyond La Niña thresholds. The tropical Pacific Ocean remains much cooler than average for this time of year, with temperatures below the surface up to 4 °C below normal in central and eastern parts comparable to the La Niña event of 1988. Trade winds are stronger than average, while cloud patterns continue to show a typical La Niña signature with suppressed cloudiness in tropical areas near the dateline. The Southern Oscillation Index SOI value for December of +27 is the highest December SOI value on record, as well as being the highest value for any month since November 1973.
La Niña periods are generally associated with above normal winter, spring and summer rainfall, particularly over eastern and northern Australia. The current event has contributed to 2010 being Australia’s the third wettest year on record, and Queensland having its wettest December on record. During La Niña periods, Tropical Cyclone occurrence for northern Australia is typically higher than normal during the cyclone season November-April, while summer daytime temperatures are often below average, particularly in areas experiencing higher than normal rainfall.
The influence of the Indian Ocean Dipole IOD on Australian rainfall is limited during the months from December through to April.
The source article Strong La Niña persists was published January 5, 2011 by Australian Governmen Bureau of Meteorology .