OREGON STATE UNIVERSITY

El Nino, La Nina battle in central Pacific

11/05/1998

CORVALLIS - Call it sibling rivalry. El Nino and La Nina are slugging it out in the central Pacific Ocean, leaving some climate forecasters puzzled but betting on La Nina to emerge victorious.

"If there's a fight going on, La Nina's winning," said Oregon State University's George Taylor, the state climatologist.

An analysis of October data from NASA's TOPEX-Poseidon satellite shows that the sea across the tropical Pacific has remained the same since June, when warm El Nino waters gave way to much cooler La Nina conditions in the tropical Pacific, said Taylor, a faculty member in OSU's College of Oceanic and Atmospheric Sciences.

Scientists studying the satellite images and other data are unsure whether the conditions are now ripe for this year's La Nina, so far a moderate one, to mature into a truly strong La Nina.

"In the Northwest, moderate La Ninas usually produce cool, very wet winters, while strong La Ninas yield somewhat wet, but very cold winters," Taylor said. "Remember the flood years of 1995-96 and 1996-97? Those were moderate La Ninas. Remember the intense cold of 1989 - when Salem was below zero and Bend hit minus 17? That was the last strong La Nina."

If, as Taylor expects, the moderate La Nina conditions continue, the coming winter is likely to be much wetter and somewhat cooler than average, with the wettest weather coming through December and the coldest weather hitting the Northwest in early 1999. There is also a good chance for significant low-level snow this winter, including the Willamette Valley, he said.

Taylor points to data that says already October has been wet.

"In October, here in Corvallis, the month is wetter than average with a half-inch above normal," he said. Normal October precipitation for the region is 3.11 inches. "The end of October is when winter begins here and it ends in February."

Forecasters at the National Weather Service's Climate Prediction Center in Washington, D.C. agree with Taylor. Weather service forecasters are now stating in their long-range forecast with "90 percent certainty" that moderate to strong La Nina conditions will develop through the end of the year and into February.