EL NINO STORM ON ITS WAY; UP TO 4 INCHES OF RAIN EXPECTED IN VALLEY.

Byline: David R. Baker Daily News Staff Writer

Don't count out El Nino just yet.

After months of relatively gentle rains, winter's full force was predicted to hit Southern California today as a powerful Pacific storm moves ashore.

Packing 15-foot surf and gale-force winds at the coast, the storm was expected to dump as much as four inches of rain in the San Fernando Valley before breaking late Tuesday.

``It looks like an important storm,'' said meteorologist Gary Ryan, with the National Weather Service in Oxnard. ``There's a tremendous potential out there, the biggest potential in a couple of years.''

That potential, Ryan said, comes from conditions over the Pacific, where an unusually cold air mass has strayed as far south as Hawaii and close to the unusually warm water fueling El Nino.

Meteorologists differ on whether El Nino indirectly contributed to this season's rainfall, but Ryan said this is the first storm with a direct link to the weather phenomenon.

``There's no doubt about that: We're on the verge of the first El Nino storm,'' he said.

This storm also marks the first appearance this winter of the ``Pineapple Express,'' a weather condition in which the subtropical jet stream aims Pacific storms right at the California coast, Ryan said. Most of the storms this winter have drifted down the coast from the north, spinning like pinwheels as they go.

Southern Californians started bracing for this kind of weather months ago, after El Nino began building strength. El Nino is a weather-altering phenomenon fueled by unusually warm water in the eastern Pacific.

But while Northern California has been socked by rain this season, with the Bay Area receiving about twice the average for this time of year, Southern California has seen rainfall totals just a few inches above normal.

Researchers note, however, that past El Ninos often didn't bring heavy rain to Southern California until mid-January or early February.

Rain from this storm system started Sunday in Ventura County, but heavy downpours weren't expected until this afternoon.

Highs today are expected to stay in the mid-50s, with temperatures tonight dipping only a few degrees. But as colder air settles in late Tuesday, lows are expected to fall into the 40s.

Winds at the shore were forecast to reach 30 to 40 mph during the height of the storm, while waves are expected to swell as high as 15 feet tonight. On Friday, 18-foot waves pounded the coast in Ventura County and Malibu, washing out roads and damaging homes.

After the storm passes on late Tuesday, showers could remain in the area for several days, Ryan said.