An El Niño year coming could mean warmer temperatures on the way!

Satellite view of the 1997 El Niño shows white areas off the tropical coasts of South and North America indicating the pool of warm water.

Satellite view of the 1997 El Niño shows white areas off the tropical coasts of South and North America indicating the pool of warm water.

La Niña and El Niño refer to cold and warm extremes of natural variation in sea surface temperatures (SST) in the tropical Pacific Ocean.  This variation in SST is coupled with atmospheric events that change weather patterns around the globe in what is referred to as the El Niño /Southern Oscillation (ENSO).

An El Niño developing this year could bring much-needed rain and drought relief to southern North America, but could also bring drought and crop failures in the Indo Pacific, southern India, and Australia.  This cycle also represents a heat pump, with colder La Niña SST favoring the capture and ocean storage of heat, and warmer El Niño SST favoring the release of some of that stored energy to the surface atmosphere . (See Upper Ocean Heat Content and ENSO for more information.)  For this reason, global air surface temperatures tend to be higher than average during an El Niño event.

The last two El Niño events were in 2003 and 2010, and June 2009-May 2010 set the highest 12-month global temperature record ever recorded.

An El Niño appears to be developing again now. The National Weather Service Climate Prediction Center forecasts with 80% certainty that an El Niño will become fully developed by fall or early winter of 2014.

There is a great deal of interest right now in whether a pattern of strong Westerly winds will develop across the Pacific, because this will indicate how strong the El Niño effects will become.  With the background of global warming, however, even a very moderate El Niño has the potential of setting a new global temperature record.  Since the El Niño, even if it develops as expected, will not be releasing its full effects until late 2014, the chance of setting a new high temperature record will be higher in 2015.

In the west and southwestern United States drought relief may be coming, but El Niñois unlikely to bring above average rains before the winter, after another severe fire season has come and gone. Despite high global temperatures expected during El Niño, higher than average rainfall across the southern U.S. can actually bring cooler temperatures to that region. For the Northeast and Midwest, if El Niño sets in it can bring a dryer than average fall, again with effects more likely to be experienced in 2015 than this year.



Category: What's With the Weather

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