Note: A La Niña occurs when sea surface temperatures in the central Pacific Ocean drop to lower-than-normal levels. La Niña typically brings above average precipitation and cool weather to the Pacific Northwest. This pattern extends through the Intermountain West, and into parts of the Great Lakes. The South is typically dry, along with the Central Plains. California typically experiences drought. The East Coast has normal snowfall, with large storms possible in the second half of winter.
Since the demise of the big 2015-16 El Niño in April, the tropical Pacific has been loitering around in neutral… and now forecasters think it’s likely to stay that way through the winter. For now, we’re taking down the La Niña Watch, since it no longer looks favorable for La Niña conditions to develop within the next six months.
It’s certainly not impossible that La Niña could still develop; forecasters are putting the chances for La Niña around 40% through the early winter. And, while a strong La Niña developed immediately after the 1997/98 El Niño, there was nearly a year of slightly-below-average temperatures following the 1982/83 El Niño before a moderate La Niña eventually developed in October of 1984, further evidence that there are many pathways that the climate system can follow after a large El Niño event.
For now, though, most signs are pointing toward a stronger chance of remaining in neutral conditions for the time being. Between the model consensus and the current lack of atmospheric response, forecasters put the odds of staying ENSO-Neutral at 55-60%. Of course, we’ll continue to keep you posted on all the happenings (and non-happenings) in the tropical Pacific
Monthly sea surface temperature in the Niño 3.4 region of the tropical Pacific compared to the long-term average for all moderate-to-strong El Niño years since 1950, showing how 2015/16 (black line) compares to other events. Climate.gov graph based on ERSSTv4 temperature data
Climate model forecasts for the Niño3.4 Index, from the North American Multi-Model Ensemble (NMME). Darker purple envelope shows the range of 68% of all model forecasts; lighter purple shows the range of 95% of all model forecasts. NOAA Climate.gov image from CPC data