Climate shifts further: La Niño is over, El Niño coming by summer

The La Nina oceanic condition, which we’ve been in for many months, has ended, and an El Nino appears likely to form in the summer or fall.

That’s the latest prediction from the Climate Prediction Center: 

It builds on the report we filed last month, when we suggested a fair chance of El Nino by mid year. That fair chance now seems to have been elevated to a pretty good chance. Spring predictions tend to be problematic, but most models see us going that way.

Thus the La Nina cool phase of Central Pacific climate is behind us, and we are in something called ENSO-neutral, ENSO being the term for the whole warm-cold cycle, El Niño Southern Oscillation.

Most climate prediction models now suggest we should shift into El Niño during the summer, and it might happen pretty quickly: “it is possible that strong warming near South America may portend a more rapid evolution toward El Niño.”

One of the things that can mean for Hawai’i is that we are likely to have a more active hurricane season. Also some other changes. More on that a little further down.

But one the questions that still challenges climate researchers is where climate change is taking the ENSO pattern broadly. There’s some suggestion that the past 40 years—since 1980—have been a little cooler than expected, a little more La Niña.

Now, many researchers say their models suggest the next few decades may swing toward more active El Niño conditions. But they don’t fully trust those models: the computer climate models of past climate don’t match up real will with actual observations of the climate. So how to be sure? A whole lot of smart people are working hard to make sense of that.  A discussion on this can be found at the ENSO blog. 

Among the variables: Warmer oceans can feed circulating storms, but warmer oceans and changing wind conditions can also cause changes in deep ocean upwellings. If they bring cool water to the surface from the deep ocean, then that could reduce the energy available to circulating storms like hurricanes. Changes in cloud cover could also create cooler surface conditions. And there are other variables.

“Heroic efforts are being done at modeling centers around the world to improve the representation of the physical processes,” wrote Kris Karnauskas, of the University of Colorado-Boulder.

That’s the long term.

For the coming year, what does an El Niño mean for us? There’s a nice NOAA fact sheet here. 

It suggests wetter weather at first, in late summer and fall, then drier. Maybe a dry winter this year. Weaker trade winds. More hurricanes and tropical storms. Warmer water around the Islands.

And sea levels slightly higher than normal, meaning big storm surf will reach farther inland.

All in all, interesting times.

© Jan TenBruggencate