LOS ANGELES » Rain forced the shutdown of one freeway, gathering snow threatened the closure of another, and heavy runoff was occurring in much of the region as a winter storm passed over Southern California on Saturday.

All eight lanes of the 110 Freeway between Pasadena and Los Angeles were closed after hours of pounding rain brought flooding, California Highway Patrol Officer Monica Posada said.

To the north, accumulating snow had the CHP poised to close the Grapevine section of Interstate 5, the common name used for the 4,160-foot high Tejon Pass, the main artery between Southern and Central California, Posada said.

The move could strand hundreds of motorists on the sometimes treacherous and often-shutdown stretch of road.

Snow was also mounting in the mountains of San Bernardino County, and was falling at elevations lower than 2,500 feet in Antelope Valley.

Hail pelted more populated areas, with small stones felt in Whittier, Temple City and Goleta.

Ojai in Ventura County and parts of the San Fernando Valley in Los Angeles had received well over an inch of rain in the 24 hours ending at 4 p.m. Lompoc in Santa Barbara County saw 1 1/2 inches.

The NWS issued flood advisories for cities including Sierra Madre, La Canada Flintridge, downtown Los Angeles and Long Beach, and there was minor flooding on Interstate 10 and State Route 90 on the west side of Los Angeles.

The cities in the advisory include some that lie near wildfire-scarred terrain, including more than 160,500 acres in the foothills of the steep San Gabriel Mountains, where the infamous Station Fire burned fiercely through the Angeles National Forest north of Los Angeles for weeks in 2009.

The burn area was expected to pose a risk of debris flows and mudslides to adjacent communities for years, but there were no reports of any immediate problems.

The wet week has been a departure from the dry, summerlike winter weather Southern California has seen so far this year.

Before rain moved in early Wednesday downtown Los Angeles had recorded only 0.79 inch of precipitation since Jan. 1. That was 4.51 inches below normal for the period.