El Nino may be waking up in Pacific Expected hot summer to worsen energy woes

Larry D. Hatfield, Chronicle Staff Writer Saturday, June 23, 2001

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It's the third day of summer and already there are warnings that a new El Nino is skulking around the far Pacific.

Worse, new government satellite photos indicate that the increasingly damaging West Coast drought is going to continue, and hot temperatures this summer will exacerbate California's energy crisis.

NASA scientists believe a new El Nino episode may be gathering in the Western Pacific, but for the time being the Pacific Ocean is dominated by a strong, larger-than-El Nino/La Nina pattern called the Pacific Decadal Oscillation.

The PDO is a long-term ocean temperature fluctuation of the Pacific Ocean that waxes and wanes approximately every 10 to 20 years. El Nino and its contrary sister, La Nina, by contrast, are short-term events during which changing ocean temperatures cause dramatic global changes in weather patterns.

The 1997 El Nino was the worst on record, causing severe winter weather in Northern California, drought in Southeast Asia, torrential rains that killed coral reefs in the mid-Pacific and other calamities.

"This continuing PDO pattern of the past three years signals more of the unusually dry conditions that have afflicted the North American West Coast," said oceanographer William Patzert at NASA's Jet Propulsion Laboratory in Pasadena.

Interpreting the latest photos from the U.S.-French TOPEX/Poseidon satellite, Patzert added: "Given the three-year persistence of the PDO pattern,

there will be a tendency to produce impacts similar to the past two summers with continuing drought and heat in the West.

"In some parts of the West, this long-lasting drought has created considerable pain. In the Pacific Northwest, water supplies are dangerously low, and temperatures should be up, which will exacerbate the energy crisis."

The satellite photos also showed warm oceanic patterns in the North Pacific and tropical Atlantic that suggest an above-normal hurricane season for the East Coast and Gulf Coast.

"The only good news in this is that the Gulf Coast and Florida could sure use the rainfall," Patzert said. "But the danger is that it could come as the recent costly and painful deluge of tropical storm Allison."

NASA's observation of the continuing PDO's characteristic warm horseshoe and cool wedge pattern in the Pacific is backed up by recent National Oceanic and Atmospheric Administration sea-surface temperature data.

Both NASA and NOAA, along with other meteorological and oceanographic agencies, are noting signs that a new El Nino is in the making.

Satellite photos and sea-surface readings show a pulse of warm water traveling eastward toward South America. El Nino traditionally returns every two to seven years, which makes a new one due probably next year.

The bulge of warm water -- called a Kelvin wave -- is forecast to arrive on the west coast of South America in late July, which should result in a modest warming of the Eastern Pacific, NASA said.

Kelvin waves, often seen before an El Nino develops, are triggered by westerly wind bursts, essentially a reversal of the normal trade winds, in the Western Pacific.

The strength of the next El Nino may depend on how much the PDO continues to dominate ocean circulation and temperature patterns, NASA said. El Nino events traditionally cause heavy rains and severe winter storms in Northern California.

The buildup of an El Nino pattern, with warmer ocean temperatures in the Western Pacific, contrasts with the cooler sea surface La Nina conditions still prevailing in the Bering Sea, Gulf of Alaska and along the West Coast.

E-mail Larry D. Hatfield at lhatfield@sfchronicle.com

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-- Martin Thompson (mthom1927@aol.com), June 23, 2001