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July 13, 1999 — The current La Niña episode will last through the winter of 1999-2000, according to scientists at NOAA's National Centers for Environmental Prediction. This means the nation will continue to experience a meteorological mix of drier-than-normal conditions on the East Coast and greater amounts of precipitation in the Northwest, and the threat of a busier-than-normal Atlantic hurricane season.

(Click here to view an animation of La Niña over a six-month period, which covers November 17, 1998 to July 6, 1999.)

La Niña is characterized by unusually cold sea-surface temperatures in the eastern and central equatorial Pacific, which trigger atmospheric patterns that influence weather around the world. For states in the Pacific Northwest, that means wetter-than-normal conditions. Along the southern tier, states typically experience drier, warmer conditions.
While its strength has diminished from the potency it had last winter, La Niña will continue to influence weather around the United States, including a continuation of drought conditions in some states, excessive precipitation in others, and a more active hurricane season with at least three major storms.

A recent weakening of the easterly trade winds in the eastern and central equatorial Pacific increased sea surface temperatures slightly, but the overall upper ocean temperature structure still indicates La Niña conditions. "In the late spring, or early summer, it's common to see some weakening in La Niña, or El Niño, but it is not an indication that the episode is going away," cautions Dr. Louis Uccellini, director of NOAA's National Centers for Environmental Prediction.

Using three of its own forecast models and the data from several others, along with information from weather satellites and data buoys in the Pacific, NOAA scientists have improved their understanding of oceanic and atmospheric connections and their skills predicting the El Niño and La Niña phenomena. NOAA accurately forecasted months in advance the impacts of the 1997-1998 El Niño, called the "Event of the Century," as well as the current La Niña event. These long-range forecasts helped communities, including farmers, city planners, emergency and utility managers, prepare for potential, often damaging impacts.

(Click here to see an animation of the development of El Niño and then La Niña. The period covers January 5, 1997 through July 4, 1999)

For regular updates about La Niña on the Internet, please visit: www.cpc.ncep.noaa.gov