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By Tom Miles
GENEVA, June 26 (Reuters) - There is a slight chance of El Ni?o weather conditions developing between July and September but the strength of any such event, usually associated with significant changes in precipitation, is unknown, the World Meteorological Organization said on Tuesday.
El Ni?o is characterised by unusually warm ocean temperatures in the central and eastern equatorial Pacific and has been linked to drought in Australia, Indonesia and northeastern parts of South America and to heavy rain in Ecuador and northern Peru, the WMO said.
In its previous update in May the WMO said it foresaw an equal chance of El Nino or neutral conditions in the second half of the year, with little chance of a return to the 2011-2012 La Ni?a conditions that ended in April.
"Now we're saying El Ni?o has a slight edge over neutral conditions," WMO spokeswoman Clare Nullis said.
Nullis said the uncertainty was due partly to the different readouts given by the various prediction methods.
While most climate models were predicting El Ni?o, some dynamic models and at least half the statistical models still pointed to neutral conditions.
The third option, a re-emergence of La Ni?a, is considered very unlikely. La Ni?a is an abnormal cooling of waters in the equatorial Pacific which can last for years and wreaks havoc on weather in Asia and the Americas, where it mainly causes crop-killing drought.
The WMO bases its reports on information from weather prediction centres and experts around the world. (Reporting by Tom Miles; Editing by Tim Pearce)