The latest fluctuations in climate conditions across the Pacific Ocean are increasing the likelihood of a La Niña winter in the U.S., the National Oceanic and Atmospheric Administration said Thursday.
NOAA predicts that water and air temperatures over the Pacific Ocean—closely watched metrics ahead of winter in the U.S.—have created La Niña conditions with a 90% chance of continuing through the winter and a 50% chance during the spring. The winter outlook is up from NOAA’s October forecast, when it predicted an 87% chance of La Niña conditions for December through February.
The changes in wind movement and water temperature in the Pacific Ocean region that cause a La Niña have a pronounced effect on weather in the U.S. and around the world. Here is how this important weather phenomenon works.
La Niña is part of a shifting weather pattern known as the El Niño-Southern Oscillation. It occurs when unusually strong trade winds—equatorial winds from the east—push the Pacific Ocean’s warm surface waters west, toward Asia. This causes cold water to rise to the surface in the central and eastern Pacific Ocean.