The United States is currently experiencing the third strongest summertime El Niño since 1950, and it could strengthen.
“Basically since mid-May things have coalesced into a very strong El Niño and I would say we are on the verge of calling it a super El Niño. That may take a few months to be certain, but that’s where it’s drifting,” said University of Colorado-Boulder researcher Klaus Wolter.
“Certainly this is the biggest event since 1997/1998 which was the last super El Niño.”
What Makes An El Niño ‘Super’?
Researchers use complex modeling including data from buoys in the tropical Pacific to predict large climate events like El Niño - all while keeping an eye on the past. According to Wolter, a big indicator is temperature. If sea surface temperatures keep going up in the tropical Pacific, so does the likelihood of a super El Niño.
“Back in 1997/1998 and in 1982/1983 - the last two super El Niños since 1950 - those two events ended up flirting with a plus 3 degree Celsius temperature anomaly in the central eastern tropical Pacific,” he said.
“We are about half way there – we are running around 1.5 degrees Celsius for the temperature anomalies in the eastern tropical Pacific. That is huge for this time of the year [July], but it’s not quite the required threshold for it to be called a super El Niño. It has to hang together for the next 4 to 6 months to reach that status,” Wolter said.
Animated map of currents and sea surface temperatures courtesy of Cameron Beccario.
What Does A Super El Niño Mean For Colorado?
Between the typical monsoon season, from July to September, along with the strong El Niño, Colorado will see a wet fall. That might test some rain-weary Coloradans, but in drier parts of the West it will be welcome.
“It makes a much bigger difference for California,” Wolter said. “They have a much better shot at recovering from the drought this winter with a super El Niño situation than with a weak to moderate one.”
According to past events, Wolter said the hallmark of an El Niño and a monsoon is the landfalling hurricanes in the eastern Pacific, most commonly in September, which equates to heavy downpours on the western slope.
With more rain, comes the possibility of more floods.
“The one drawback of this is that historically, if you look at big floods in Colorado they occur more than twice as often with an El Niño summer, like this year,” Wolter said.
The last super El Niño in 1997 caused severe flooding in Fort Collins, and resulted in five deaths and an estimated $200 million in damages.
How Will A Super El Niño Affect Colorado’s Snowpack?
If the El Niño continues into the winter, it will affect the frequency of storms, said Wolter.
“You actually might get some fairly big snowstorms pretty early in the season, which can set the base. If you don’t get that, if you don’t have a string of storms in Oct. or even Nov. going into the winter, then the chance of recovering [the snowpack] during the winter is minimal.”
But if the El Niño holds together into spring 2016, the snowpack could recover.
“The super El Niño in 1983 went right into the summer. That’s really the best case scenario. If you get a reasonably wet fall, put some good snow down early in the season, make it through the winter on a shoestring if you will, then get that wet spring, that can more than make up for a dry winter,” Wolter said.
That situation would benefit both the ski industry and the parched southwest, including Lake Mead, which relies on the Colorado River basin for water.
Colorado has seen false starts in El Niño-related weather before. During the spring of 2014, weather patterns and conditions seemed to point to a strong event, but the El Niño did not progress over the summer.
But this 2015 El Niño is different.
“There’s no way it’s going to disappear any time soon,” Wolter said. “The question is will it last well into the spring, or is it going to die early next year. But it will be around for the next 6 months, there’s no question about that.”
By October, Wolter will know for sure.
“Right now I’m thinking it’s a 70 to 80 percent chance of a super El Niño.”