Global & Disaster Medicine

La Niña Makes a Quiet Return

La Niña is the cooler sister to El Niño. La Niña draws cool water up from the depths of the eastern Pacific, energizes the easterly winds, and pushes warm surface water back toward Asia. (Note the ripples of warm water moving west across the equator.) In turn, global atmospheric circulation and jet streams shift with the changing heat and moisture supply from the vast Pacific Ocean.

During La Niña events, the weather tends to grow warmer and drier across the southern portion of North America, from California to Florida. Cooler than normal temperatures usually prevail across western Canada, Alaska, and the U.S. Pacific Northwest. Over the central and eastern Pacific Ocean, clouds and rainfall become more sporadic, while rainfall tends to increase dramatically in Indonesia and the western Pacific. Weather conditions in late 2017 seemed to fit with that pattern.

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