Tuesday, 29 July 2014

El Niño back to fifty fifty

2014-07-29_elninowatchThe odds of an  El Niño developing this year, and with it the chances of an ultra-hot year for the planet, have dropped considerably. The Australian Bureau of Meteorology reported this afternoon 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. 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.
Given the current observations and the climate model outlooks, the Bureau’s ENSO Tracker has shifted to El Niño WATCH status. This means the chance of El Niño developing in 2014 is approximately 50%, 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.
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