We’d like our forecasts—both weather and climate—to be simple and certain. Because of the fluid and chaotic nature of the ocean and atmosphere, however, forecasts are never about certainty: they’re about probability.

How does El Niño affect U.S. winter temperature and precipitation?

Chances that an El Niño will occur by summer are above 70%, hitting 80% by the fall. But subsurface temperature anomalies have tapered off some from earlier this spring, decreasing the odds the event will be as strong as the El Niño of 1997-98.

El Niño typically favors stronger hurricane activity in the central and eastern Pacific basins, and suppresses it in the Atlantic basin. Where does that leave the 2014 hurricane outlook?

If the climate conditions that indicate ENSO are best measured as seasonal averages, will scientists wait for conditions to persist three months before declaring El Niño underway?

ENSO arises from changes across the tropical Pacific Ocean. So why does ENSO affect the climate over sizable portions of the globe, including some regions far removed from the tropical Pacific Ocean?

Though ENSO is a single climate phenomenon, it has three states, or phases, it can be in. The two opposite phases, “El Niño” and “La Niña,” require certain changes in both the ocean and the atmosphere because ENSO is a coupled climate phenomenon. “Neutral” is in the middle of the continuum.

A team of climate scientists—actual nerds!—discuss the current El Niño Watch and offer perspectives and analysis on the progression of El Niño.

This National Geographic video explains the origins of the El NiÃo Southern Oscillation using animations and shows the impacts on humans, wildlife and habitat, particularly in the United States.

Pacific ENSO Update

The Pacific ENSO Update is a bulletin of the Pacific El Niño-Southern Oscillation (ENSO) Applications Climate Center, providing information on climate variability for the U.S.-Affiliated Pacific Islands. This newsletter is intended to supply information for the benefit of those involved in such climate-sensitive sectors as civil defense, resource management, and developmental planning in the various jurisdictions of the islands.

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