While not writing off the prospects of an El Nino pattern influencing rainfall patterns this summer altogether, the Bureau of Meteorology says the latest signals show that the chance of an El Nino in 2014 has clearly eased.
The Bureau’s latest ENSO statement released yesterday said that, despite the tropical Pacific Ocean being primed for an El Niño during much of the first half of 2014, the atmosphere above has largely failed to respond, and hence the ocean and atmosphere have not reinforced each other.
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.
“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. 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,” the latest ENSO statement says.
The Bureau now rates the chances of an El Nino developing in 2014 at approximately 50pc, which remains significant at double the normal likelihood of an event.
El Niño is often associated with wide scale below-average rainfall over southern and eastern inland areas of Australia and above-average daytime temperatures over southern Australia. Similar impacts prior to the event becoming fully established regularly occur.
The Indian Ocean Dipole (IOD) index has been below −0.4 °C (the negative IOD threshold) since mid-June, but needs to remain negative into August to be considered an event. Model outlooks suggest this negative IOD is likely to be short lived and return to neutral by spring. A negative IOD pattern typically brings wetter winter and spring conditions to inland and southern Australia.