From the Weather Center
by John Simon
The term La Niña comes from the Spanish for little girl. According to the National Oceanic and Atmospheric Adminstration (NOAA), it describes an oceanic and atmospheric cooling pattern that can occur in the Pacific Ocean every few years. In a normal year, winds along the equator push warm water westward. Warm water at the surface of the ocean blows from South America to Indonesia. As the warm water moves west, cold water from the deep rises up to the surface. This cold water ends up on the coast of South America.
In the winter of a La Niña year, these winds are much stronger than usual. This makes the water in the Pacific Ocean near the equator a few degrees colder than it usually is. Even this small change in the ocean’s temperature can affect weather all over the world.
La Niña lowers the temperature of the central Pacific Ocean by from three to five degrees celsius, and can persist for up to five months. La Niña events have occurred for hundreds of years, and records exist since 1903.
La Niña can produce fewer snowstorms and blizzards here in the Northeast, although it does not affect seasonal snowfall predictions, as snow forecasts are generally not predictable more than one week in advance. During La Niña, the temperatures across the continental United States will typically be above, near or below average. The climate pattern of La Niña affects the position of the jet stream and therefore the weather across all of the United States.