Weak La Niña follows potent El NiñoA year ago, the equatorial Pacific was pulsing with heat, due to one of the most intense El Niños on record. But the current La Niña has been relatively quiet.
The 2015-2016 El Nino was one of the most intense on record. But the current La Niña, the cool sister pattern to El Niño, has been relatively quiet. In a report issued in December 2016, the NOAA Climate Prediction Center described the latest La Niña as “weak” and likely changing to neutral conditions in early 2017. El Niño and La Niña are periodic weather patterns resulting from interactions between the ocean and the atmosphere in the tropical Pacific Ocean. While El Niño knocks down trade winds and pushes warm water from the western Pacific to the Americas, La Niña pulls up cool water from the depths of the eastern Pacific, and pushes the warm water back toward Asia. That’s why regions that get drenched with rain and snow during El Niño often go dry during La Niña events, and vice versa, as atmospheric circulation and jet streams shift with the changing heat and moisture supply from the vast Pacific Ocean. The video below explains how El Niño and La Niña work. La Niña conditions began to appear in July and August 2016. During last year’s El Niño, surface water temperatures were as much as 2.5° C above the 1981-2010 norm. During the current La Niña, temperatures have not dropped more than 1 degree below normal. Bill Patzert is a climatologist at NASA’s Jet Propulsion Laboratory. Patzert said in a statement:
The patterns following the El Niño of 2015–16 have been starkly different from what occurred after the last major event. According to a statement at NASA’s Earth Observatory:
According to Mike McPhaden of the NOAA Pacific Marine Environmental Laboratory:
Mike Halpert, deputy director of the NOAA Climate Prediction Center, noted that the current pattern is somewhat similar to 1982–83, when another strong El Niño was followed by a relatively modest La Niña. Halpert said:
Bottom line: Although the 2015-2016 El Nino was one of the most intense on record, the current La Niña has been relatively quiet. Read more from NASA’s Earth Observatory
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