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El Niño
Mon Oct 24, 2005
Listen in RealAudio 
Hi, I’m Bryan Yeaton for The Weather Notebook. With Fall upon us, many of us are
already starting to wonder what this Winter will be like. Some scientists are looking at
the El Niño potential as a predictor for this season. But first, let’s try and remember just
what El Niño is!
Now often known as the El Niño Southern Oscillation—or ENSO—the phenomenon
was first noticed by fishermen off the western coast of South America. In some years,
around Christmastime, their nets were coming up empty. In Spanish, the Christ-child
is called El Niño, so the name was also applied to this seasonal event.
Every so often—usually between two and seven years—warm waters usually found
farther out in the Pacific Ocean are pushed east, closer to shore. Normally, the colder,
upwelling water hauls up nutrients that feed the fish on which the locals rely, and
without this fish food, hauls in the nets are pretty bleak.
In ENSO years, the shift in Sea Surface Temperatures (SST) disrupts air circulation
above this part of the ocean, causing powerful thunderstorms. This pattern, in turn,
affects the jet streams, and thus air circulation around the globe. During El Niño,
warmer and drier conditions will be found over Southeast Asia, while the southern US
is wet and cool. Southern California is usually quite stormy, and in the Northeast US,
warmer conditions can impact industries such as ski areas and maple syrup
production.
When the warm Sea Surface Temperatures shift farther west than normal, we call it "La
Niña", or sometimes called "El Viejo." This scenario produces conditions nearly
opposite of El Niño.
The forecast for this season—so far—is neutral; neither a significant El Niño or La
Niña event is expected this year.
The Weather Notebook is a program of the Mount Washington Observatory, and is
generously funded by Subaru of America.
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