The globally averaged sea surface temperature in 2013 was among the 10 highest on record, with the North Pacific reaching an historic high temperature. ENSO-neutral conditions and a negative Pacific Decadal Oscillation pattern had the largest impacts on global sea surface temperature in 2013.

El Niño and La Niña conditions occur when abnormally warm or cool waters accumulate in tropical latitudes of the central and eastern Pacific Ocean. The Oceanic Nino Index is the tool NOAA scienitsts use to watch for these temperature changes. 

How El Niño is like different flavors of ice cream.  Seriously.

The forecast seems stuck on repeat. Why are we still calling for El Niño?

June 2009 SST anomalies

As of late August 2014, tropical atmospheric temperatures appear to be responding more strongly to the ocean than they typically do at this early stage of El Niño development.   

OLR anomalies in 2012 versus 2014

Where is El Niño?  How is this year different from 2012 when El Niño was predicted, but never arrived?  

How do changes in the equatorial Pacific Ocean impact places much farther away? The answer for the tropics, at least, lies in changes to the equator-wide atmospheric circulation called the Walker Circulation. 

June 2014 SST anomalies

Why hasn't El Niño been declared yet?  The answer might lie in the gradients of sea surface temperatures across the tropical Pacific Ocean.  

Sea surface temperatures are up. So why haven't forecasters declared El Niño conditions? 

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