LA NINA MAY NOT PULL ODD WEATHER TO L.A.

Byline: David R. Baker Daily News Staff Writer

Despite predictions that La Nina would bring Los Angeles a dry winter and possibly worsen the fire season, the weather phenomenon now appears to be losing strength, according to scientists at NASA's Jet Propulsion Laboratory.

The pool of cold Pacific water that is the heart of La Nina has shrunk to one-fourth the size it was in May, even as warm water left over from El Nino remains, said Bill Patzert, a researcher at the National Aeronautics and Space Administration laboratory in Pasadena. If La Nina dissipates before it hits Los Angeles, the area could face a more typical wet winter.

``It's really a question at this point: Will La Nina wane as El Nino lingers?'' he said.

La Nina and El Nino form the opposite ends of the same climatic cycle, with El Nino fueled by unusually warm water in the eastern Pacific and La Nina driven by cold. Each can bring drought to some parts of the planet while drenching others with rain.

Just two weeks ago, National Weather Service experts predicted that La Nina - a phenomenon whose effects are roughly the opposite of El Nino's - would bring Los Angeles a slightly drier year than normal.

Don't count La Nina out yet. Patzert and other weather experts say the cold water pool often fluctuates in size as the phenomenon builds.

``El Nino and La Nina are things that change slowly over time,'' said Ants Leetmaa, director of the weather service's Climate Prediction Center. ``It's pretty dangerous to look week-to-week.''

He said the center's forecasts predicted that after rapid cooling during the summer, ocean temperatures would rebound before cooling again.

``The forecasts are still on track,'' he said.

Although the current La Nina conditions are following on the heels of this last winter's El Nino, they often occur years apart and don't alternate in an orderly progression.

This summer has been unusual, with a growing La Nina sharing the ocean with remnants of the strongest El Nino on record. Although La Nina is already affecting rainfall in Southeast Asia, it hasn't noticeably influenced North America's weather yet, Leetmaa said.