NOAA’s Climate Prediction Center announced earlier this month that there was a 50 percent chance that the phenomenon would develop during the northern hemisphere summer or fall.
But there is already a new and very warm pool of water in the western Pacific. Satellite monitoring indicates it is expanding eastward toward the coast of South America.
That pool is illustrated in three dimensions in the graphic to the right, which uses data from NOAA’s Global Ocean Data Assimilation System (GODAS).
Should the warming develop into a strong and mature El Niño, it could help bring drought-breaking rains to California once the state’s rainy season returns late this year.
El Niño occurs, on average, every three to five years. The ocean warming is linked to weather shifts that have brought drought in Australia, Southeast Asia and India, as well as flooding in parts of the Americas.
The most severe El Niño on record killed more than 2,000 people in 1997-98 and caused an estimated $33 billion in damage.
The new potential episode could bring problems to fishermen along the coast of Peru, where the phenomenon got its name.
The government there cautions that the commercial fishing industry could be adversely affected by the arriving warm waters, which drive off schools of cold-water anchovy that the fishermen depend on.
Even before meteorologists understood El Niño and its effects, Peruvian fishermen coined the term, which is Spanish for the little boy. The name comes from the phenomenon's tendency to arrive around Christmas time (Christ’s birth).
Once thought to affect only a narrow strip of water off Peru, El Niño was recognized in the 1980s as a large-scale oceanic warming that can cause massive weather shifts on a global scale.
Graph: NOAA Environmental Visualization Lab