Department Seminar: Jin-Yi Yu

Title: El Niño Is Changing: What Can We Expect from the 2026 Super El Niño?

Abstract: NOAA officially declared the onset of El Niño on June 11, 2026, and current forecasts suggest that it may strengthen further during the 2026–27 winter. This raises a timely question: will this year bring another “super El Niño,” possibly even stronger than the two most recent super El Niño events of 1997–98 and 2015–16?

This seminar examines that question from a new perspective on ENSO dynamics developed by my group at UC Irvine. Traditionally, El Niño has been understood mainly through tropical Pacific dynamics, especially the buildup of warm water volume along the equator. Our work suggests that this tropical pathway is only part of El Niño development; a second pathway, originating from ocean–atmosphere coupling in the subtropical northeastern Pacific, particularly off Baja California, can also strengthen or weaken a developing El Niño.

I will compare the evolving 2026 conditions with those observed during the 1997–98 and 2015–16 super El Niño events to illustrate the insights provided by combining traditional tropical ENSO dynamics with the new subtropical ENSO perspective. I will also discuss what this framework may suggest about the evolution of the 2026 super El Niño and its possible impacts on Southern California.