The Australian Bureau of Meteorology (BoM) has shifted its ENSO status to alert, meaning there's a 70% chance or greater of an El Niño. I've updated the sidebar with the latest announcement (pdf version) from BoM.
The Pacific Ocean has shown some renewed signs of El Niño development in recent weeks. Above-average temperatures in the tropical Pacific Ocean have warmed further in the past fortnight, while the Southern Oscillation Index (SOI) has generally been in excess of El Niño thresholds for the past three months. Climate models suggest current conditions will either persist or strengthen. These factors mean the Bureau's ENSO Tracker Status has been upgraded from WATCH to ALERT level, indicating at least a 70% chance of El Niño occurring.
Not all indicators have shifted towards El Niño. Tropical cloudiness near the Date Line and trade wind strength are close to average, suggesting the atmosphere is still not firmly linked with the warmer ocean below. However, trade winds have weakened several times over the past few months and SOI values have remained generally negative, suggesting at least some atmospheric response to the underlying ocean conditions.
International climate models expect the warm tropical Pacific Ocean temperatures to persist, with most models predicting values will remain near or beyond El Niño thresholds for the next two to three months. Regardless of whether or not El Niño fully develops, warmer-than-average tropical Pacific Ocean temperatures, combined with cooler waters currently to the north of Australia increase the chance of some El Niño-like impacts. For many parts of Australia, this suggests below average rainfall and above average temperatures in the months ahead (as shown by the November–January Climate Outlook).
Here are the POAMA model projections - it doesn't look as if it will be earth shattering if it does eventuate. As always, click the image to enlarge it:
This is what the monthly sea surface temperature anomalies for October looked like:
And here's a comparison of sub-sea surface temperatures with earlier in the year:
The updates come out every fortnight. Here is a link to pdf files of the current and past updates.
If you want to learn more about ENSO, this is probably the most extensive article I've written, and it has lots of links so you can explore further.