It all starts in the Pacific Ocean off the coast of Peru, where roughly every five years warmer-than-average water temperatures generate El Niño, a global-scale climate cycle. During El Niño winters, expect big snowfalls from Southern California to Texas and drier conditions in the northern Rockies and Canada. (Remember the snow shortage at the Vancouver Olympics? El Niño.) Its opposite is La Niña, in which the Pacific cools down, bringing dry winters to the Southwest and cold, snowy winters to the Pacific Northwest mountains. (East Coast weather isn't much affected, though climatologists theorize that El Niño curbs Atlantic hurricanes.) La Niña and El Niño both last three to five years, but in the past few decades La Niña has occurred half as often. And in addition to switching back and forth, the ocean enters a neutral phase between the two. What phase are we in now? In July the Pacific transitioned from a one-year El Niño back to La Niña. "We can anticipate moderate La Niña conditions this winter, starting in January 2011," says Greg Carbin, a meteorologist at the NOAA-NWS Storm Prediction Center. See you at Whistler!
Filed To: Science