Persistent 'La Nada' Likely to Hold Through Spring 2014

An ongoing period of near-normal sea surface height conditions across the equatorial Pacific Ocean, called "La Nada," will likely continue until the spring of 2014, according to the National Weather Service's Climate Prediction Center.

The condition has been in effect since spring 2012 and represents something of a conundrum for forecasters.

"Without an El Niño or La Niña signal present, other, less predictable, climatic factors will govern fall, winter and spring weather conditions," said climatologist Bill Patzert of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Long-range forecasts are most successful during El Nio and La Niña episodes. The 'in between' ocean state, La Nada, is the dominant condition, and is frustrating for long-range forecasters. It's like driving without a decent road map -- it makes forecasting difficult."

During the past several decades, roughly half of all years have experience La Nada conditions, in comparison to 20 percent for El Niño and 30 percent for La Niña, according to NASA.

And while La Nada may be considered something of a neutral in-between, Patzert notes that some of the wettest and driest winters can be attributed to it.

"Neutral infers something benign, but in fact if you look at these La Nada years when neither El Niño nor La Niña are present, they can be the most volatile and punishing. As an example, the continuing, deepening drought in the American West is far from 'neutral,'" he said.

Sea surface height is partly a result of temperature: as the ocean warms, levels rise and vice versa. Meanwhile, the temperature of the upper ocean can significantly affect both weather patterns and climate. For this reason, NASA officials say they will keep an eye on the persistent La Nada event in order to determine what role the Pacific Ocean may play in the world's climate over the next several months.