Mild El Nino may be brewing, researcher says

By Jan TenBruggencate
Advertiser Science Writer

A pool of warmer-than-normal water off the South American coast has the trappings of an El Nino event, but even if it is, it should have minimal impact on this year's hurricane season, said a University of Hawai'i researcher who studies Pacific climate variation.

"It looks like if we have an El Nino, it will be weaker than the last two and will be later in the year," said oceanography professor Roger Lukas.

The National Weather Service's Climate Prediction Center generally agrees, although not necessarily for the same reasons.

"For the moment, near-neutral (sea surface temperature) conditions are most likely in the tropical Pacific during the winter 2001-2002," the agency said in its long-term assessment of Pacific climate.

Honolulu National Weather Service meteorologist Paul Jendrowski said that if the assessment is accurate, "it should be pretty normal. We don't have a strong signal either way."

In Hawai'i, El Nino events, with superheated tropical equatorial waters, can cause more frequent and stronger storm activity during hurricane season and can cause winter drought.

Lukas said it is too early to predict what will happen later this year, but there are no signs that suggest a coming El Nino, if it does develop, will be anything but a weak one.

There are suggestions this one is unique among recent warm episodes. For the past two decades, El Nino events have developed as a massive pool of warmer-than-usual water moves from the Western Pacific along the equator to the coast of the Americas.

But there is a second kind of El Nino, not seen since before weather satellites and modern climate monitoring equipment, in which the hot water develops near the Americas and moves west.

That's what appears to be happening this time, Lukas said. The waters off the northwestern corner of South America are as much as 3 degrees Centigrade — roughly 5 degrees Fahrenheit — warmer than normal for this time of the year.

This warming could dissipate, or it could continue to develop, generating all the weather conditions of a normal west-to-east El Nino.

"The atmosphere doesn't care how the ocean got warm. It just cares that it got warm," Lukas said.

The good news for the Islands is that the warm water is well south of the hurricane-forming region off the coast of Mexico, Lukas said.