SAN DIEGO ---- After three years of drought, California just might escape a fourth one, but there's still a lot of uncertainty, water experts said Monday.

A rain-bringing El Nino condition appears well-established, speakers said at a workshop held in San Diego by the California Department of Water Resources. The weather pattern, which brings warm water to the eastern Pacific, doesn't guarantee rain in California, but it makes it more likely.

Although the forecast generally pointed to greater supplies of water, speakers mindful of the weather's notorious unpredictability hedged their prognostications with plenty of warnings that conditions could change for the worse.

Winter is the state's rainy season, recharging Northern California's reservoirs, which supply much of Southern California's water. Snow deposited in the Sierra Nevada melts during the spring and summer, further filling reservoirs.

So the next few months will determine whether 2010 is another dry year or if the drought will end.

But water officials say the state has a long way to go to recover from three years of lower-than-normal precipitation. Reservoirs are far below capacity. For example, Oroville Reservoir is at 37 percent capacity, about 60 percent of its normal level. So conservation will continue to be needed, especially for arid Southern California, which is literally at the end of the pipeline from its water sources, from Northern California and the Colorado River basin.

El Nino is important because it tends to bring rain and snow to both these sources.

"I'm cautiously optimistic that we may get a normal year," said Mike Dettinger, a research hydrologist with the U.S. Geological Survey in San Diego. "I'm really dubious about whether we'll get a really good year."

A recent storm in Central California moistened watershed soils, making it easier for additional rain to flow into rivers and reservoirs, said Dettinger, who is also a researcher at UC San Diego's Scripps Institution of Oceanography.

Signs appear modestly positive for rain from El Nino, Dettinger and two other speakers said. But they disagreed somewhat on the weather condition's strength.

The El Nino is weak, said Timothy J. Brown, director of the Western Regional Climate Center in Reno. And even a strong El Nino doesn't always bring above-average precipitation, he said.

However, the latest signs are that the El Nino is strengthening, said Klaus Wolter, a research associate at the Earth Systems Research Laboratory at the University of Colorado at Boulder. Strong El Ninos more reliably bring water to Southern California, somewhat less often to Northern California, Wolter said. Weak El Ninos have much less effect.

"If you want water this winter, you really have to root for a strong El Nino," Wolter said. Moreover, the effects of a strong El Nino often persist into the spring, he said, bringing unseasonably late storms.

And other weather patterns across the planet, from the Azores to the Indian Ocean, also are linked to El Nino, Wolter said, and bode well for a wet winter for California.

"If El Nino is reasonably strong in the winter, don't be surprised if you get a wet spring," Wolter said.

Call staff writer Bradley J. Fikes at 760-739-6641. Read his blogs at bizblogs.nctimes.com.