The winter of 2015, which featured an El Niño, was brutally cold in New England. Jan Ellen Spiegel / CT Mirror

The average weather for Connecticut this winter is likely to be warmer and wetter than normal. That’s the forecast from the folks who do this for a living — the National Oceanic and Atmospheric Administration’s Climate Prediction Center.

The reason: there’s a strong El Niño in the mix.

It’s not the best news, especially coming after the relentless rain and flooding since mid-July. But at least it doesn’t include predictions of the kind of extreme weather caused by climate change.

It doesn’t seem to, anyway.

The effect of El Niño on the Northeast’s weather is tricky to predict, more so than most other regions, according to Jon Gottschalck, chief of the Operational Prediction Branch of the Climate Prediction Center.

“It’s exactly the stuff that keeps me up at night,” he said in an interview, a few days after NOAA presented its winter outlook to more than 100 journalists in a virtual news conference. “The Northeast is one of the areas actually in which the El Niño impact or relationship is one of the weakest. In New England, there’s a lot of factors that control the weather.”

That means in New England, unlike in other parts of the country where El Niño effects override almost all other factors, El Niño may not run the show.

Then again, it might.                                                                                       

The winter temperature prediction. NOAA

The forecast is an average, Gottschalck emphasizes. That means conditions can run to extremes in either direction at several points but over time balance out to something that seems far more moderate.

“The winter outlook is probabilistic in nature, meaning that the maps show these areas that are most likely to be warmer or colder than normal and wetter or drier than normal,” he said. “However, the nature of a probabilistic forecast means that other outcomes are always possible, just less likely. And in fact, for our probabilities to be reliable, the less likely outcomes must occur from time to time.”

So get ready for just about anything and everything.

The winter precipitation prediction. NOAA

The basics of El Niño

El Niño is an equatorial Pacific climate phenomenon. But its impacts reach all the way here. It produces tropical thunderstorms and clouds that warm the Pacific, which in turn has an impact on air currents, notably the jet stream.

“It tends to just throw a big rock into the climate world, the earth’s atmosphere and ocean-coupled systems,” Gottschalck said. “That causes a lot more things to occur in the upper levels of the atmosphere.”

The result tends to be warmer and mostly wetter weather trends in the U.S. during an El Niño winter. In places like Florida, Gottschalck said, he can almost guarantee loads of rain. A few U.S. areas run drier, as do other parts of the world — in some cases, dramatically so.

But New England’s other weather factors, some of which are produced by climate change, can be strong. We already saw that this summer. An El Niño normally tamps down Atlantic hurricane activity. But because the North Atlantic — as well as the Pacific and other oceans — had warmed so much due to climate change, hurricane activity was high. Many didn’t hit land, but they were out there.

Climate change also resulted in the hottest June, July and August ever, with July simply the hottest month, period. September clocked in as the warmest September on record and the most abnormally hot month globally.

Gottschalck points out that usually once or twice during El Niño winters, there are some pretty good snowstorms — nor’easters — along the East Coast. One reason is that an El Niño pushes storm tracks south and east, which means they can utilize some of that extra moisture from all that summer and ocean warmth to “juice up,” as he put it.

“So these storms are also very strong and energetic because they are able to link between colder air to the north and much warmer and wet conditions to the south, and those storms can very much become extremely dynamic, extremely strong,” he said.

There may be fewer big storms, but the big ones could be, well, big.

Cases in point — The El Niños of 2018-19, 2014-16, 2009-10, 1997-98 and 1982-83, which included the “snowpocalypses” and “snowmageddons” of January 2018, February 2010 and the ice storm of January 1998.

Gottschalck doesn’t think this winter — the December-February time period — will bring some of the super El Niños of, say, 1997-98, but he does anticipate a strong one that will get more intense throughout the winter.

There’s another set of factors at work in New England, around the northern latitudes of the planet. Their wonky names are the Arctic and North Atlantic Oscillations. They’re kind of a ring, or fence, that runs through Canada, New England, northern Europe and Asia to the U.S. Pacific northwest. Cold Arctic air is to the north of it, and warmer air is to the south.

As winds strengthen and weaken, the jet stream becomes wavy and essentially causes that boundary to pulse north and south.

“What will happen at times is that jet stream pattern will break, and a big, big chunk of cold air from that area will break off and head south. A lot of people sometimes will call that the polar vortex,” Gottschalck said, adding that’s not really what it is. “It could break off in Asia; it could break off in Europe; it could break off in southern Canada and go right into New England or the Great Lakes. So that’s the key. That’s probably the biggest factor.”

“What happens is you can get these two- or three-week periods of just terrible cold,” he said. With an El Niño, he added, it may happen a little less over the course of the winter. “So that’s why the forecast is for warmer even though that may sound at odds,” he said.

Preparing for all of the above

A warmer winter may sound like good news for New England’s power grid operator, ISO-New England. The ISO’s biggest concern remains protracted periods of cold when heat and power may wind up competing for the same limited supply of natural gas.

The grid can typically handle the shorter cold snaps. Storms often have a double-edged sword, though. They knock power out, which is a problem for the utilities, not the ISO. While difficult for customers, outages reduce grid demand for electricity until the wires and poles are back where they need to be.

But the ISO has had its scares — the winter of 2017-18 in particular. Overall, it wasn’t particularly cold, but a long cold spell around New Year’s saw backup fuel supplies dwindle. Since then, the ISO has instituted a 21-day rolling forecast that is updated weekly, using shorter term predictions from the National Weather Service. The big three-month outlook from NOAA is less critical to the ISO, said its spokesman, Matt Kakley.

“We settled on a 21-day forecast, and we publish that every week,” said Kakley, who called it the sweet spot between the weather forecast being solid enough but with still enough time to take action. “What that’s trying to do is try to synthesize some of those variables and say, what’s the weather? How cold is it going to be? What is our fuel supply entering the stretch? What would we expect to happen based on the weather? And to see that coming a few weeks ahead of time.”

More recently, the ISO has begun working with the Electric Power Research Institute, EPRI, to develop a new tool to make better long-term grid projections, expressly because of the increased role weather will play.

The study, called Operational Impact of Extreme Weather Events, is examining 2027 and 2032, not just in terms of demand for, say, an increase in electric vehicle charging needs or heat pump usage, which the ISO has already been doing. But it also looks in terms of specific weather scenarios paired with power resources, such as solar, in cloudy or snowy periods — and at potential technology changes and resource additions, such as offshore wind and other renewables that may feel the impacts of weather more acutely.

The point again, said Kakley, is to “try to use modeling software, advanced technology to figure out how can we best see problems coming before they arrive.”

But for Connecticut’s Emergency Management Division, NOAA’s El Niño predictions essentially mean planning for an all-of-the-above winter. More road salt, or less? More warming centers, or fewer?

“We’re already having conversations with DOT about making sure they have enough contractor drivers for this winter, making sure that they have the resources going into the winter,” said Bill Turner, state emergency management director. “You never really know what you’re going to get. But it could be a pretty significant snowstorm.”

Even with a mild forecast like the one this year, Turner said he always adds a huge caveat: it only takes one of these events to really cause problems.

One of the things that worries him is a lesson from the rainstorms of the last few months. They may have been catastrophic in some locations, but other places, even in a small state like Connecticut, got far less precipitation.

“The tricky part is because they’re happening more and more, we don’t want to get complacent,” he said. “We try not to sound that alarm every time we think something weatherwise is going to happen … You get everybody together and start talking it through, and then certain parts of the state don’t see it, and other parts get clobbered.”

Which is precisely the message from Gottschalck at NOAA, despite the mild forecast.

“Winter is going to occur in Connecticut. It’s going to be cold. In fact, it’s going to be several weeks, multiple weeks where you have below normal temperatures,” he said. “But over this season as a whole, typically you have a little bit less of those during a strong El Nino.”

Jan Ellen is CT Mirror's regular freelance Environment and Energy Reporter. As a freelance reporter, her stories have also appeared in The New York Times, The Boston Globe, Yale Climate Connections, and elsewhere. She is a former editor at The Hartford Courant, where she handled national politics including coverage of the controversial 2000 and 2004 presidential elections. She was an editor at the Gazette in Colorado Springs and spent more than 20 years as a TV and radio producer at CBS News and CNN in New York and in the Boston broadcast market. In 2013 she was the recipient of a Knight Journalism Fellowship at MIT on energy and climate. She graduated from the University of Michigan and attended Boston University’s graduate film program.