Rain could continue until March
IF you reckon you’re over all this rain we’ve been having, think about how you might feel if it kept going for a couple of months.
The Bureau of Meteorology says the weather pattern responsible for our flooding – called La Niña – could hang around until March.
La Niña refers to the cooling of the central and eastern Pacific Ocean that increases the probability of wetter conditions in Australia, particularly in the east.
It recently became the conventional meteorological label for the opposite of the better-known El Niño.
It refers to the warming of the central and eastern Pacific that leads to a major shift in weather patterns across the Pacific.
In Australia, El Niño events are associated with an increased probability of drier conditions.
A major La Niña event continues to affect the Pacific Basin and long-range forecast models suggest it is likely to persist into autumn.
The tropical Pacific Ocean remains much cooler than average for this time of year, with temperatures below the surface up to four degrees below normal in central and eastern parts.
That is comparable to the La Niña event of 1988 when 1234.6mm was dumped into the Amberley rain gauge.
The current event has contributed to 2010 being Australia’s third wettest year on record, and Queensland having its wettest December on record.
The 368.2mm recorded at Amberley is the highest reading since the standout year of 1991 when 394.4mm bucketed down.
During La Niña periods, cyclones are more likely for northern Australia during the cyclone season (November-April), while summer daytime temperatures are often below average, particularly in areas experiencing higher than normal rainfall.
Another effect of La Niña is values of the SOI (Southern Oscillation Index). A La Niña event is sometimes called an anti-ENSO (anti-El Niño-Southern Oscillation) event.
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: Translates from Spanish as “the girl child”
El Nino: Translates from Spanish as “the boy child”