The odds that an El Niño will develop by summer appear to be getting stronger.
In a report released yesterday, the Australian Bureau of Meteorology raised the odds of an El Niño developing by summer (winter in the Southern Hemisphere) to greater than 70 percent. And in his monthly analysis, Klaus Wolter of NOAA’s Earth Systems Research Laboratory noted that the evolution of conditions over the past four months suggest that a strong El Niño may well be on the way. He found nine cases that look similar to what has been occurring in the equatorial Pacific:
Of the 9 cases selected in this fashion, three remained either neutral (1960) or dropped back to La Niña status within a year (1961, 1984). The other SIX cases look like a roll-call of historic El Niño events since 1950: 1957-58,’65-66, ’72-73, ’82-83, ’86-88, and ’97-98. Not only does this confirm the increased odds of an El Niño in 2014 (first pointed out four months ago on this wepage), it also translates into higher odds for a moderate-to-strong El Niño.
Characterized by unusually warm ocean temperatures in the equatorial Pacific Ocean, El Niño tends to bring wetter than normal conditions across the southern United States in winter, drought in the West Pacific, and increased risk of bushfires in Australia. More precipitation is possible in parts of the West, including now-parched California. But there are no guarantees, of course.
The animation at the top of the post depicts the evolution of sea surface temperatures in the equatorial Pacific over the past 12 weeks. It shows warmer than normal temperatures developing in the eastern Pacific and near the International Date Line. Conditions are still neutral. But models used to predict how conditions will evolve show that sea surface temperatures in the Pacific are likely to cross the El Niño threshold by the summer, according to the Australian report:
Although the El Niño–Southern Oscillation (ENSO) is currently neutral, surface and sub-surface ocean temperatures have warmed considerably in recent weeks, consistent with a state of rapid transition.