Environment

El Niño

The robust El Niño event anticipated for more than a year is finally coming to fruition, according to the latest observations and forecasts. NOAA's latest monthly analysis, issued on Thursday morning, continues the El Niño Advisory already in effect and calls for a 90% chance of El Niño conditions persisting through the summer, with a greater-than-80% chance they will continue through the end of 2015.

The Australian weather agency has also declared the on-again, off-again El Niño ocean warming that stumped forecasters last year to be back on with a vengeance.

The phenomenon is associated with extreme weather around the world, and happens when trade winds over the tropical Pacific weaken, allowing sea-surface temperatures to rise. In a classic El Niño, the ocean and atmosphere are synchronized in a mutually reinforcing pattern that pushes warm sea-surface temperatures (SSTs) and thunderstorm activity along the equator eastward for thousands of miles, from Indonesia toward South America (see Figure 1). Sometimes the atmosphere doesn't respond to a "kick" from the ocean, and an embryonic El Niño fails to develop. This was the case last spring, when a powerful oceanic Kelvin wave (a broad, shallow, slow-moving impulse) pushed warm water east across the Pacific tropics.

Australia’s Bureau of Meteorology now says that a “substantial” El Niño will develop through late this year while the U.S. Climate Prediction Centre says there is an 80 percent chance the warming will persist through all of 2015.

Its early phase may be responsible for recent above-normal rainfall on the U.S. Gulf Coast and Great Plains.

Further ocean warming predicted for the months ahead threatens to devastate India’s agriculture with drought after untimely rains earlier this year already wiped out crops.

El Niño forecasts issued in May tend to be more accurate because models become more dependable from this point on, experts say.

A strong El Niño that was predicted to develop during late 2014 never really set in, leaving forecasters scratching their heads.

Some meteorologists say that the phenomenon could combine with another shift in ocean temperatures called the Pacific Decadal Oscillation (PDO).

The PDO brought record warmth to parts of the North Pacific this past December and January, and is predicted to stay strong.

If it were to combine with a significant El Niño, global temperatures would most likely soar even higher than during the recent record warmth.