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El Nino (What Child Is This?)

     

      We will remember for some time the record storm that buried the front range in several feet of snow in late October. On one hand, cities were paralyzed. Roads were closed, businesses shut down, and a state of emergency declared. On the other hand, cities came to life. Neighbors helped neighbors dig out their homes, people with four-wheel drives helped take needed medical personnel to hospitals, and search crews found and saved numerous stranded motorists. Uplifting stories of good deeds and heroic rescues dominated the usually depressing newscasts.

      Such an unusual storm had to have a cause, and El Nino was quick to get the blame. That made sense; after all we have certainly been hearing a lot about El Nino's power to impact our weather lately. Immediately after the front range storm, the Denver Post ran a headline claiming El Nino had socked its first punch for the winter. But the Rocky Mountain News ran a headline citing experts as claiming El Nino was not to blame for the storm. More important than who scooped whom (the News was more accurate in this instance), this illustration shows that El Nino is perhaps the most talked about yet least understood weather phenomenon of recent times.

 What Is El Nino?

      For many years, Peruvians have noticed a warming of the waters in the Eastern Pacific about every four years. Because the warming often begins in late December, it was given the name El Nino, in this case, "the Christ child." Meteorologists, knowing of its existence but long believing its effects were only local, pretty much ignored El Nino and concentrated their studies on many other weather phenomena. One such phenomenon was the Southern Oscillation.

The Connection Down Under

      The Southern Oscillation (SO for short) was first documented in the 1930s. Sir Albert Walker noticed that when the air pressure was high in Darwin, Australia, it was low in Tahiti (an island in the South Pacific), and vice versa. He also noticed that the air pressure seemed to change, or oscillate, in a fairly regular pattern. But it wasn't until 1969 that a direct link between El Nino and the SO was first noticed. Only in the past twenty years has there been a focus on these connected events which likely effect the climate and weather over much of the earth. 

Not An Only Child

      When the air pressure is high in Darwin, an El Nino is present in the Eastern Pacific. But when the air pressure is low in Darwin, the waters of the Peruvian coast cool well below normal. This cooling has been called La Nina, the Sister. A La Nina usually occurs between each El Nino.

      It is this Southern Oscillation and El Nino/La Nina cycle that affects climate in many parts of the world. To avoid cumbersome names (or from a lack of understanding), the media generally mentions only El Nino when referring to this larger phenomenon. 

Effects Of El Nino

      The effects of El Nino are very difficult to predict. One reason is that El Ninos vary in many ways. No two El Ninos give the same results. California has experienced very wet conditions in some El Nino years and drought during others. To further complicate things, other phenomena occur (such as jet stream movement) that also affect weather and climate. Making local predictions based on El Nino is seldom successful.

 Here At Home

      All weather is the result of a variety of conditions at a given time. If we knew every variable involved, the impact each variable had, how the variables interacted, and could measure each variable precisely, then we might be able to consistently and accurately predict weather anywhere. El Nino, in the large picture, definitely impacts weather and climate. But we cannot accurately say that our weather this winter will be due to El Nino. According to Michael Glantz, one of the nation's leading experts on El Nino, specific local weather events cannot be blamed on nor denied cause by El Nino.

      The accompanying graph shows average valley winter temperatures and El Nino/La Nina events for a forty year period. While winters colder than average have occurred in the valley during recent El Nino years, there is not a strong, predictable relationship between El Nino and our average winter temperatures. The movement of the jet stream more likely has a stronger correlation to weather in the San Luis Valley.

 El Nino Is Here!

      While we may not be able to directly attribute our daily weather to El Nino, we can certainly document that El Nino has indeed invaded Colorado. Pick up a Sunday newspaper and count the "El Nino Sale" advertisements (better hurry and buy that four-wheel drive). Listen to the newscast and count how many times you hear "El Nino" mentioned by someone other than the weather anchor. Try to find someone, anyone, who has not heard of El Nino. El Nino has come to stay (and, apparently, left his sister behind)!

 The Future Of El Nino

      Although a few decades ago El Nino was left untouched by scientists, meteorologists around the world are now devoting much time and energy to unraveling the mysteries of this tropical phenomenon. In time, as data is gathered and analyzed, we might be better able to understand and predict the global effects of El Nino. The economic and humanitarian benefits of being better able to predict drought or flooding well in advance are obvious. In the meantime, it will be interesting to see how our perception of El Nino changes with time. Although it is mainly the fear of the cold that keeps El Nino in our minds, perhaps in some small way, especially this time of year, we are attracted to the irresistible warmth of a child.


 
2006  Dirk Oden


 

 

 

 
   
 
 

This site was last updated 09/05/06