AUSTIN (KXAN) — El Niño may be just weeks or days from beginning, but it’s not completely guaranteed to develop this year… yet.

Meteorologist Nick Bannin spoke to Tom DiLiberto, Climate Scientist at NOAAs Office of Communications, about what has to happen for El Niño to officially begin, and what would stop it from happening.

Meteorologist Nick Bannin: Tom, we’re all talking El Niño now. It seems all but certain that we’ll be having an El Niño here as we head through the summer into fall and winter, but there’s still the chance that we won’t. What would have to happen to prevent El Niño this year?

Tom DiLiberto, Climate Scientist at NOAA: So El Niño is not just a discussion about ocean temperatures in the Pacific Ocean, you have to have the atmosphere jump on board with it. It’s what we call it a coupled system. Basically, it’s a dance between the ocean and the atmosphere. So even if the ocean is above average, if the atmosphere doesn’t want to dance, you don’t have an El Niño. And while yes, right, there is a 90% chance of El Niño persisting into Northern Hemisphere winter once it, if it does form, there’s still about a 5% to 10% chance of there not being an El Niño forming, because the atmosphere doesn’t really join. And the reason for that is, counterintuitively, just how warm the oceans have been.

So, the oceans are warm in the central and eastern Pacific Ocean, where we normally look at for El Niño, but they’re also warm in the western Pacific Ocean, they’re warmer than average. And El Niño actually relies on the difference between those two basins, especially in ocean temperatures. Now, if everything is warmer, there is a possibility that, potentially, that the atmosphere doesn’t change as we expect it to or might be a little bit slow to jump on board, but we’ll have to see how that happens or when that may happen as we move through the summertime.

Sea surface temperature anomaly
Sea surface temperature anomaly

Bannin: So, I’ve read about the spring predictability barrier that makes it tough to forecast both El Niño and La Niña into the future. When do we get past that?

DiLiberto: We’re getting past it pretty soon and right now. As we move into the summertime, especially when we get it June, I would expect and we do tend to see an increase in the skill of our forecasts. So we’re getting to the end of that period, and lot more confidence will be coming in the next several months as we continue to look at what’s going to be happening in the tropical Pacific and if El Niño does form.

Bannin: There are some indications we could not just be looking at El Niño but a strong El Niño. What difference does the strength of an El Nino mean to what we see weather-wise?

DiLiberto: So El Niño is not a storm. So it’s not like El Niño is going to hit us next Tuesday or El Niño is coming in a week or so. El Niño is talking about kind of the background state, I like to think of it as El Niño is drawing up the play for a basketball team to run, but Mother Nature are the players. And either you have an NBA team or sometimes you have a bunch of seven year olds and who can bring that play to exactly how you’d like it to be. So the strength of El Nino really is tied to how strong a connection we might see to how it affects the weather across the mid-latitudes where we live, the stronger in El Nino, the more confident we can be that it will affect the jetstream and the weather that we see across the United States. It’s not necessarily saying that we’re going to see a stronger amount or larger amount of precipitation or hotter temperatures or drier {conditions} depending on where you are, it’s talking about the signal that you’re more likely to actually see that impact over a longer period of time like a month or three month period of time.