Weather experts are predicting a “super El Niño” this winter.
The National Center for Atmospheric Research (NCAR) in Boulder said current conditions are likely to develop into one of the strongest El Niño events on record. According to NCAR, El Niño events are "characterized by warmer-than-average temperatures in the Tropical Pacific Ocean." The phenomenon tends to peak in December and can significantly change weather patterns across the globe. La Niña, conversely, is a cool phase in ocean temperatures. The last El Niño occurred in 2015-2016.
NCAR measures El Niños with a metric called the Niño 3.4 Index. It's a measure of change in sea surface temperatures over time. The center said El Niño conditions occur when the average Niño 3.4 Index is above +0.5 degrees Celsius.
"An official El Niño event requires the running three-month average index to be +0.5 degrees C or higher for five consecutive months. The Niño 3.4 Index for August was +1.3 degrees Celsius," a recent analysis stated. "NCAR’s new forecasting system predicts the index will rise to an average of +2.4 degrees over the months of December, January, and February."
Stephen Yeager, a project scientist with the center’s Climate and Global Dynamics Laboratory, told KUNC the impacts of El Niño are uniquely difficult to predict in Colorado.
"The United States tends to get wetter and colder in the south, from California all the way across to Florida, whereas the northern part of the country from the state of Washington and across tends to be drier and warmer than normal," Yeager said. "States in the middle, like Colorado, don't have very strong connections to El Niño that are consistent.”
The new El Niño event could either diminish or boost winter snowfall significantly, depending on how the weather pattern develops.
“We might see more snowfall sort of in the southern mountains of Colorado, maybe the southwest,” Yeager said. “It's unclear exactly how far north that impact will reach. Whether we'll get a really epic snow year is hard to say, but I would say there's a potential to see extreme winter weather in one direction or another.”
Yeager said this winter’s event is expected to be comparable to the major El Niño of 1997 and 1998, one of the most powerful in history. That event caused massive flooding, drought, and other natural disasters at the time. The 1997-98 El Niño peaked at a three-month average of +2.4 degrees Celsius on the Niño 3.4 Index.
But Yeager said when it comes to the center's predictions, he makes no promises.
"Only time will tell if we’re accurate," Yeager said. "But we believe our system has something to offer, and we’re excited to be able to contribute this knowledge to the conversation going on right now about the impacts El Niño may have in the coming months.”
