Winter Outlook: strong El Niño, warmer weather

First published in Landings, November, 2015.

Get ready for El Niño!

El Niño refers to a period of months when the waters of the central and eastern Pacific Ocean are much warmer than average. The warm water in turn causes the atmosphere above the ocean to grow warmer, which then affects the climate over much of the United States. A strong El Niño will typically influence the climate and weather during the winter. This year’s El Niño is amongst the strongest on record.
The El Niño phenomenon was first noticed by South American fishermen in the 1600s. The warmer-than-usual water that brushed the western shores of the continent during El Niño blocked upwelling of cold water which brought the anchovy schools close to shore. Not a good thing for the anchovy fishermen.

The winter forecast for New England predicts a normal amount of  precipitation but a distinctly greater chance of warmer temperatures. Still, Mother Nature could throw us another winter of heavy snowfall. NOAA graphics.

The winter forecast for New England predicts a normal amount of precipitation but a distinctly greater chance of warmer temperatures. Still, Mother Nature could throw us another winter of heavy snowfall. NOAA graphics.

The two strongest El Niño events on record prior to this year, 1982-1983 and 1997-1998, produced quite mild winters from the Pacific Northwest to the Northeast. “If people remember those years, they might expect a repeat this winter,” said NOAA Regional Climate Services Director for the Eastern Region Ellen Mecray. “But not so fast,” she cautioned.

“We can look back at past years when El Niño was strong and get an idea about what this winter will be like, but there are many factors that affect the weather here in the Northeast,” she said. “Typically, a strong El Niño year means warmer temperatures and more precipitation.” But, she said, that is if you only look at the effect of El Niño. Other factors influencing winter weather include the North Atlantic Oscillation, jet streams, and oceanographic factors. “The Gulf of Maine is warmer now than it was in past El Niño years. Maybe that means stronger storms this winter. We aren’t really sure,” Mecray said. Mecray said that one of the best sources to explain the uncertain nature of an El Niño winter is in a blog published by NOAA’s Beyond the Data (www.climate.gov/news-features/blogs/beyond-data).

Outlook_map_temp2015_NOAAFrom Beyond the Data: “Let’s say you have a favorite establishment, where everybody knows your name, and they bring you ‘your’ beverage on sight. And then one night you go in, and based upon your past experience, you sort [of] expect the bartender to bring you your favorite beer. Instead, maybe he unexpectedly brings you a warmer-than-normal beer, or even <shudder> a wine cooler. El Niño is like that bartender. Seeing him when you walk in may tilt your odds toward getting your favorite beer, but it’s not a guarantee. In other words, sometimes El Niño is the bartender who doesn’t bring you what you ordered.”

“The challenge is that we are far away from the epicenter of El Niño,” Andy Pershing, Chief Scientific Officer and Ecosystem Modeler at the Gulf of Maine Research Institute, said. “We’ve had a mild start to the fall, which is consistent with a strong El Niño,” he continued. “And the seasonal outlook from NOAA is more confident this year than in past years.”

NOAA released its climate outlook in September which predicted that this will be one of the strongest El Niños on record. So it is likely that the Northeast has a wetter and warmer than average winter to look forward to. The Climate Prediction Center said there is a 95% chance of El Niño continuing through winter. The warmer weather should peak in late fall or early winter, then gradually weaken through spring 2016.

Pershing said that just because the winter may be warmer on average, that may not be the case in Maine, specifically. “Last winter there was a mini El Niño and a warm winter was predicted. We know how that turned out in Maine,” he laughed. Last winter in Maine was warmer than average in December and January, but then February was a month of cold weather and a lot of snow. “It was a bit of a caveat,” said Pershing. “There is always a chance of a caveat again this winter in Maine.”

“It’s important for people to know that this is a prediction and not as accurate as a three-day weather forecast even though we are more confident in the prediction this year,” Pershing said.