Environment

Latest Forecast: Odds of an El Niño Drop

ImaGeo iconImaGeoBy Tom YulsmanNov 6, 2014 3:46 PM
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This map shows how sea surface temperatures in the Pacific vary from average. During an El Niño event, anomalously warm water develops in the eastern tropical Pacific off the coast of South America. (Source: NOAA) The odds of an El Niño developing this winter have faded somewhat, further dimming hopes for a break in California's historic drought. Back in June, forecasters pegged the odds of an El Niño emerging by fall and winter at 80 percent. Today, a bulletin from the National Climatic Data Center reports that the long predicted El Niño has still not emerged, and that the odds of one emerging have dropped from a two in three chance last month to 58 percent now. From the Climate Prediction Center:

Overall, several features across the tropical Pacific are characteristic of borderline El Niño conditions, but collectively, the combined atmosphere and oceanic state remains ENSO-neutral.

ENSO stands for the El Niño-Southern Oscillation, a phenomenon in the tropical pacific that oscillates between a cool phase, called La Niña, and a warm phase, known as El Niño. The map at the top of this post shows sea surface temperature anomalies — meaning how they vary from average — in the tropical Pacific. See that elongated, patchy area of warm water in the eastern tropical Pacific, off the coast of South America? That's the El Niño struggling to be born. Here's what sea surface temperatures in the tropical Pacific looked like during the powerful El Niño of 1997/1998:

That pool of warm water extending westward from South America along the equator is a signature of El Niño, and in this case it is obviously much bigger and warmer than what's being observed now. Here are some details from the Climate Prediction Center about what we might expect in the months ahead:

Similar to last month, most models predict El Niño to develop during October-December 2014 and to continue into early 2015 (Fig. 6). However, the ongoing lack of clear atmosphere-ocean coupling and the latest NCEP CFSv2 model forecast (Fig. 7) have reduced confidence that El Niño will fully materialize . . . If El Niño does emerge, the forecaster consensus favors a weak event. In summary, there is a 58% chance of El Niño during the Northern Hemisphere winter, which is favored to last into the Northern Hemisphere spring 2015 (click CPC/IRI consensus forecast for the chance of each outcome).

Hopes for a strong El Niño were already fading in September and October. And last month, NOAA issued a seasonal forecast saying that California's record-setting drought would likely persist or intensify in large parts of the state. Today's lowering of the El Niño odds may douse any lingering hopes that Californians may have had for significant relief. But hold on — nature sure does have a way of going off script, as it has with El Niño. So might some confluence of weather patterns not predicted by the models bring more relief than expected? Let's hope so.

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