El Nino's Global Reach
The defining characteristic of El Nino is sustained above-average temperatures in the middle of the Pacific Ocean. Traditionally, Peruvian fishermen recognized the phenomenon when the catch would decline as weak trade winds led to warmer waters around the west coast of South America, decreasing the nutrients in the water and thus the number of fish it could support. Now, a much more regimented system takes measurements of ocean temperatures throughout the Pacific. The Oceanic Nino Index looks at temperature anomalies in the region known as Nino 3.4 — between 5 degrees north and 5 degrees south latitude and between 120 degrees and 170 degrees west longitude. El Nino is declared if the average sea surface temperatures there are at least 0.5 degrees Celsius (0.9 degrees Fahrenheit) higher than normal for five consecutive overlapping three-month periods.
The El Nino in 2015 was widely anticipated but was considerably delayed. A weak El Nino was first announced in March, after which it gradually strengthened as sea surface temperatures continued rising during the next several months. Currently, forecasters with the National Oceanic and Atmospheric Administration's Climate Prediction Center give a very high probability (greater than 90 percent) for El Nino lasting through the end of 2015 and a high probability (85 percent) of it lasting into spring of 2016. Forecasts show that the strength of this El Nino will remain high through the winter.
A monster El Nino and its potentially extreme weather effects make for good headlines. However, it is important to remember that an El Nino only increases the probability of certain weather patterns; it does not make them a foregone conclusion. Still, historical El Nino events indicate what the probable weather patterns will be and how they can and will affect the global economy.
The El Nino weather pattern likely contributed to many of the ongoing droughts around the world, such as those in Central America and Southeast Asia; dry conditions in these regions are typical in El Nino years. El Nino also might have contributed to the weaker-than-normal monsoon season in India. As autumn (September-November) approaches in the Northern Hemisphere, the droughts in Indonesia, Malaysia, Vietnam and Thailand, among other countries, are likely to continue. El Nino also increases the likelihood that the season will be drier for parts of Australia and southern Africa. In contrast, areas on the western coast of South America can expect much wetter conditions than normal. As the Northern Hemisphere moves into winter (December-February), the predominant weather patterns include continued dryness in many Southeast Asian countries, particularly Indonesia, while parts of North America will experience more rainfall and other areas on the continent will have warmer temperatures. If this El Nino extends through March-May, the weather pattern could bring continued rainfall in North America and alter the 2016 monsoon season
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