NOAA’s Climate Prediction Center (CPC) has issued their monthly El Niño diagnostic discussion for May 2014 (permalink). The summary has increased the probability of an event from “exceeding 50%” to “exceeding 65%”. The CPC and International Research Institute (IRI) provides a quick look at the longer term forecasts, which peak at 78% to 79% for Nov or Dec of 2014. The Australian Bureau of Meteorology also issued their bi-weekly update on Tuesday, which cites the likelihood of an El Niño at least at 70%. As the more detailed discussion at Real Climate notes, even with an 80% prediction, there still is a 20% chance that an El Niño will not form.
At this point, however, the more interesting discussion is the forecast intensity. Currently, the average of all the models have the event peak at around 1°C (with the highest model at 1.5°C). This is significantly less than the record-breaking El Niño events in 1983 and 1997-8 of nearly 3°C. The expert discussions are careful to note that strength forecasts at this point are highly unreliable, so there is no guarantee that this will either be an especially mild or strong event.