This year’s El Niño is ramping up to be a doozy, predicted researchers with the National Oceanic and Atmospheric Administration (NOAA) during their monthly El Niño update on 10 September. Mike Halpert, deputy director of NOAA’s Climate Prediction Center in College Park, Md., said that the 2015–2016 El Niño could become one of the strongest three on record. There’s a 95% chance that it will hang around until next spring.
The global pattern of temperatures, winds, and rainfall known as El Niño recurs every 2 to 7 years. It starts with warming of eastern Pacific waters and potentially leads to heavy downpours in California, which is currently in a severe drought.
After an El Niño predicted in early 2014 shriveled into a no-show dubbed “El Wimpo,” officials remain cautious about what this year’s conditions may bring. But in a phone call yesterday with reporters, they suggested nonetheless that this year’s El Niño may be topped only by an unusual El Niño that lasted from 1986 to 1988 and by another massive El Niño that roughed up both coasts during the winter of 1997–1998.
Although a precise forecast is still up in the air, Halpert said that models project a cooler winter with above-average precipitation across the southern United States from central California to the mid-Atlantic. In the northern states and Hawaii, winter could be warmer and drier than usual.
“We don’t throw a 95% percent chance out very often,” said Halpert about the forecast’s unusually high level of confidence that the pattern will hold well into next year. “The real question is more how strong it stays through the winter,” he noted.
The forecast may sound like good news to California, but a strong, wet El Niño could also do considerable harm. The heavy rains that the monster 1997–1998 El Niño brought to the state overflowed flood channels and washed away roads, ultimately killing 17 people and causing more than a half billion dollars’ worth of damage. Around the same time, tornadoes in Florida and ice storms in the Northeast killed 70 more and destroyed $800 million in property.
Climate scientist Daniel Swain of Stanford University in Stanford, Calif., said he also thinks that a strong El Niño is likely to bring more rain to California than usual, but models simply can’t predict how much. “From a risk management perspective, it probably does make sense to start doing things to mitigate the risk of flooding or mudslides,” he said, “but some of California’s biggest floods occurred during years that had no El Niño at all.” One rainier-than-average year won’t erase the drought, Swain added, which Halpert had also noted.
Measuring a Moving Target
A typical El Niño event occurs when warm Pacific water that usually pools around Indonesia and the Philippines accumulates instead along the equator nearer to South America. This repositioned ocean heat, just a few degrees warmer than usual, can scramble global weather patterns and disrupt fisheries and may last up to a year.
Scientists can’t predict the triggering of El Niños, but once one is in motion, climate models can predict seasonal outcomes relatively accurately on the basis of observations like sea surface temperatures and wind speeds from earlier in the year. Swain confirmed that NOAA’s models of this year’s anomaly have shown themselves to be accurate so far. “They called for a strong El Niño by early fall, and that’s exactly what ended up happening,” he said, “which increases our confidence that forecasts moving forward into winter will turn out to be correct.”
NOAA will release a more precise 3-month seasonal forecast on 17 September.
—Kerry Klein, Freelance Science Writer; email: [email protected]
Citation: Klein, K. (2015), NOAA predicts strong El Niño, Eos, 96, doi:10.1029/2015EO035535. Published on 11 September 2015.