Published Wednesday, June 18, 1997, in the San Jose Mercury News

Powerful El Niño Forecast

Weather Impact Could Vary From Drought to Storms, Flooding

Mercury News Staff and Wire Report

WASHINGTON -- What could be the strongest El Niño in more than a decade is developing with surprising speed in the eastern Pacific, threatening to disrupt weather patterns throughout the world. Exactly what that means for the Bay Area and central California is uncertain, however. While the last powerful El Niño in 1982-83 brought heavy winter rains and flooding across the state, the climate phenomenon can just as easily lead to drought, climate forecasters said Tuesday.

``We're trying to find out what the El Niño years have in common, and what's different one year to the next, and why there might be such differences,'' said Kelly Redmond, regional climatologist at the Western Regional Climate Center in Nevada. ``It's a pretty important question because they have such huge impacts on the West.''

El Niño is the name scientists use for a warming trend in the waters of the eastern equatorial Pacific every two to seven years. It was named by Peruvian fishermen for the baby Jesus because it usually becomes noticeable around Christmas time, leading to poor catches.

As the surface waters warm, moist air rises and disrupts the normal flow of the jet stream winds that steer weather patterns around the world.

Scientists at the National Oceanic and Atmospheric Administration's Climate Prediction Center declared an El Niño in the making last week. Tuesday, they said the warming trend is developing at an almost unheard-of pace.

``This is not the average El Niño. This is looking much more like a big one than a small one. This is shaping up to have a large, significant impact all across the globe,'' said Ants Leetmaa, director of the center.

California's coastal waters are already warming. In May, surface temperatures were 2 to 3 degrees above normal off Monterey Bay, 3 to 4 degrees above normal off San Francisco Bay and up to 6 degrees above normal along the north coast and off Baja California.

The National Marine Fisheries Service said this could bring good fishing to Southern California, as more tropical species of fish move northward. The early appearance of migrating yellowtail, albacore and bluefin tuna this summer may be related to El Niño, they said.

But it could hurt fisheries farther north, including those for salmon and rockfish, they said. And beachcombers may notice more dead seals and sea lions washed up on shore, as the fish these animals normally eat become scarce.

The phenomenon is expected to persist at least through next winter, bringing wetter, cooler weather for the southern half of the United States and warmer-than-normal temperatures for the north, from Washington state to the western Great Lakes.

In California, El Niño probably will bring unusually rainy weather going south, Redmond said.

The forecasters made no prediction for the Northeast, although historically El Niño events have meant average to above-average temperatures and precipitation in the region.

Although climatologists are divided over how big a role El Niño played in the epic flooding of the Missouri and Mississippi basins in the spring and summer of 1993, the record is clear about the havoc created by the 1982-83 warm event.

The tropical trade winds actually reversed for a time, and weather disasters visited almost every continent -- drought in Australia, Africa and India, Peruvian deserts deluged with 11 feet of rainfall, a surplus of mosquitoes from a warm, wet spring in the Southeastern United States, and a rise in snakebites in Montana as the reptiles followed mice and water down to lower elevations from parched high country.

``I think this event could well approach the 1982-83 El Niño in scale,'' Leetmaa said.

A network of ocean buoys and other instruments scattered across the Pacific, plus satellite observations, gives scientists a constant stream of data about what's happening to temperatures and sea levels in the world's largest body of water. And computer models are getting ever better at tracking El Niños and their companion cold events, La Niñas.

But even though they can see changes coming months in advance, scientists are still uncertain what actually triggers the events. Some blame undersea earthquakes or volcanic activity, but most believe it's related to the ocean's constant struggle to keep balance with wind patterns and seasonal changes.

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Mercury News Staff Writer Glennda Chui contributed to this report.