Weather forecasters are closely watching sea water levels in the Central Pacific after images taken by the U.S./European Jason-3 satellite mission, managed by NASA’s Jet Propulsion Laboratory in Pasadena, showed high sea levels building up by the beginning of May.
According to the forecasters, this patch of high sea level is slowly traveling eastward through the tropical Pacific Ocean along the equator, as shown by Jason-3 images, according to a specialized NASA website. This type of signal is often a precursor to an El Niño event.
Such large El Niño events affect weather and climate across the globe, particularly in the western United States.
In California, El Niños usually mean above-average winter rainfall, while Oregon and Washington typically see drier-than-normal winters.
An April 9 image from Jason-3 showed most of the ocean at neutral heights. This was about the time that temperatures, convection and rainfall rates in the equatorial Pacific Ocean returned to normal, after a mild La Niña late last year. Sea levels began building up last month.
El Niños happen when a series of waves spread warm water from west to east along the equator, causing high sea levels in the Central Pacific and sometimes as far east as the coastlines of Central and South America. The warm water is currently confined to the subsurface, with no warming at the ocean surface.
During a large El Niño, like the 2015-16 event, a huge area where sea levels are more than a foot higher than normal is visible in Jason-3 images. The high sea level is caused by a thick layer of warm water in the upper several hundred feet of the ocean.
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