The El Niño / La Niña climate pattern that alternately warms and cools the eastern tropical Pacific is the 800-pound gorilla of Earth’s climate system. On a global scale, no other single phenomenon has a greater influence on whether a year will be warmer, cooler, wetter, or drier than average. Naturally, then, the ears of seasonal forecasters and natural resource managers around the world perked up back in early March when NOAA’s Climate Prediction Center issued an “El Niño Watch.”
The “watch” means that oceanic and atmospheric conditions in the tropical Pacific Ocean are favorable for the development of El Niño within the next six months. These maps reveal one of the most significant of those favorable signs: a deep pool of warm water sliding eastward along the equator since late January.