La Nina is a atmospheric, climatic and oceanic phenomenon affecting primarily the Pacific.
La Nina is Spanish for "the girl" and is paired with El Nino.
It occurs when the eastern equatorial ocean temperatures are lower than normal. This results in stronger trade winds. In addition, the jet stream moves northward, bringing in Arctic air during the winter.
The climatic changes result in a greater upwelling of deep ocean waters, which affects the type and diversity of sea life.
Effects on the weather in North America:
(1) colder in Alaska, Canada and North Central states
(2) wetter in the Northwest and parts of the Midwest
(3) drier in the southern United States
(4) warmer in parts of the southern United States
(5) more severe hurricanes
