The threat of an El Nino weather event is receding with atmospheric conditions over the Pacific largely failing to respond to warming ocean waters, the Bureau of Meteorology.
The chances of an El Nino, which typically bring warmer-than-average temperatures to Australia and south-east Asia and lower rainfall, are now about 50-50 for such an event forming in 2014, the bureau said.
The reduced El Nino prospects, down from 70 per cent in earlier forecasts by the bureau and other agencies such in the US, will be welcomed by farmers and others concerned about conditions favouring drier and warmer weather.
Still, at 50 per cent, such an event – marked by relatively warm waters in the equatorial central and eastern Pacific compared with western regions – cannot be ruled out.
“While the chance of an El Niño in 2014 has clearly eased, warmer-than-average waters persist in parts of the tropical Pacific, and the (slight) majority of climate models suggest El Niño remains likely for spring,” the bureau said. “Hence the establishment of El Niño before year's end cannot be ruled out. If an El Niño were to occur, it is increasingly unlikely to be a strong event.”
In El Nino years, rainfall is typically lower-than-normal across southern and eastern inland parts of Australia while maximum temperatures tend to be warmer than usual. Even without El Nino thresholds being crossed, those weather conditions can be present – as has been the case for much of the country so far this year.
July is not quite done but most of NSW will have about one-fifth of the usual rainfall for the month, including in Sydney, with just over 16 millimetres of rain making it the eighth consecutive month of sub-average falls.
Temperatures have also been on the warm side, with Sydney forecast to end July with tops for the final three days of 23 degrees – more than six degrees above average. The city will also beat the record set for the most number of days with a maximum of at least 18 degrees – with the tally to reach 24, eclipsing last year’s high of 23 such days.
Earlier this year, temperatures in the eastern Pacific climbed, prompting some climate experts to predict a strong El Nino could be possible. However, after a burst of westerly winds – the reverse of the usual pattern along the equator – atmospheric conditions failed to reinforce the underlying ocean temperature differences.
“As a result, some cooling has now taken place in the central and eastern tropical Pacific Ocean, with most of the key NINO regions returning to neutral values,” the bureau said.
Its ENSO track has now been cut to a “watch” status from “alert”.