After several months of speculation due to borderline conditions in the Pacific Ocean, El Niño is finally here, according to scientists at the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center. They issued an El Niño advisory on March 5, 2015. While El Niño events typically trigger changes in the weather across the globe, the current El Niño event is weak and is therefore not expected to have substantial and widespread impacts on global weather in the near future. Unfortunately, this means that the drought-stricken western United States will likely not receive enough rain to end the current drought cycle. At the same time, NOAA said:
… certain impacts often associated with El Niño may appear in some locations during the Northern Hemisphere spring 2015.
Those impacts could include a cooler, wetter spring for some. The presence of an El Niño may also mean fewer hurricanes after hurricane season begins again June 1.
Sea surface temperature patterns in the Pacific Ocean during El Niño (warm) and La Niña (cold) events. Image via NOAA.
El Niño events reoccur about every 2 to 7 years and are associated with warmer sea surface temperatures in the central and eastern Pacific Ocean along the equator. An El Niño is an often dramatic illustration of the integral link between Earth’s oceans and atmosphere. The Scripps Institution of Oceanography said:
Typically, the ocean surface warms up by a few degrees Celsius. At the same time, the place where hefty thunderstorms occur on the equator moves eastward. Although those might seem like small differences, it nevertheless can have big effects on the world’s climate.
Those big effects may be typical … but perhaps not this year.
Ocean conditions characteristic of an El Niño event have been in place since November 2014, but atmospheric conditions over the past few months did not meet the criteria for issuing an El Niño advisory. During the past month, changes in westerly winds and precipitation patterns over the ocean have shifted to a more favorable El Niño-like signal. Hence, scientists finally issued the March 5 El Niño advisory.
Scientists predict that there is a 50% to 60% chance that the current El Niño event will continue throughout northern summer of 2015.
How El Niño typically affects rainfall in the U.S. However, the current El Niño is weak and may not, for example, help alleviate California’s drought.
Criteria for issuing an El Niño advisory. Image via NOAA.
Bottom line: On March 5, 2015, NOAA scientists announced that El Niño has arrived. The event, which is marked by warm sea surface temperatures in the equatorial Pacific, is weak and scientists do not expect it to have any major effects on global weather patterns in the near future.