It’s Spring, but El Nino Doesn’t Care--Just Watch

El Nino isn’t done yet.

Rain, thundershowers and--yes, in May--even some snow are expected to hit Southern California today, and meteorologists say the much-discussed climatic phenomenon is at least partially responsible.

Kevin Stenson, a meteorologist with WeatherData Inc., which provides forecasts for The Times, said the storm due this morning is a cold one that spent many of its formative hours over the chilly waters of the Gulf of Alaska.

Normally at this time of year, such storms move inland well north of California, riding powerful, high-altitude jet stream winds that cut across British Columbia and the Pacific Northwest.

This week, however, thanks largely to El Nino, the jet stream is split, with one branch following the usual track and the other barreling south along the Pacific Coast before heading inland through California.

Today’s storm is riding this southern branch, and Stenson said Orange County residents can expect showers this morning and possible thunderstorms in the afternoon. Rainfall totals will vary, depending on location. Coastal areas of the county can expect about a quarter of an inch,, with less expected farther inland before the storm moves east late Wednesday or early Thursday.

He said several inches of snow will fall above 5,000 feet in the Tehachapi, San Gabriel and San Bernardino mountains.

“The precipitation will start about dawn on Tuesday, with scattered showers through the afternoon,” Stenson said. “There’s enough extra energy in the system for a pretty good chance of thunderstorms in the afternoon and evening.”

Unlike winter storms, which usually include prolonged periods of steady rain and snow, today’s spring storm will produce spotty precipitation, Stenson said.

“You could be in one place where they get a lot of rain or another, close by, where they get hardly any,” Stenson said.

He said the scattered showers should continue through Wednesday, with a continuing possibility of isolated thundershowers through Wednesday night and a chance of a lingering sprinkle or two Thursday morning.

After that, it should get warmer and drier through the weekend, with partial cloudiness and high temperatures from the upper 60s to the mid-70s.

That’s the way the weather is supposed to be for Southern California during May, but this has been a soggy spring.

Normally, during May, the Civic Center in Los Angeles gets about a third of an inch of rain, but with less than half of the month gone, it already has received 1.03 inches.

A year ago, meteorologists with the National Oceanographic and Atmospheric Administration predicted that because of El Nino, Los Angeles would get about twice the normal amount of rainfall this season, which runs from July 1, 1997, through June 30, 1998.

Thus far, the total for the season is 28.94 inches, just about double the normal total for the date of 14.67 inches.

Times staff writer Roberto J. Manzano contributed to this report.