Preparations Underway for SoCal Rain

Los Angeles - A cold storm is expected to bring the season's first substantial rainfall Monday, but a second storm expected later in the week will not be as big as first feared, forecasters said today.

A revised weather analysis put out at midmorning by the National Weather Service in Oxnard said the second storm will be much weaker than originally predicted, and will not arrive until Thursday.

The first storm is expected to arrive Sunday night, and on Monday it could produce from a half-inch to 1.5 inches of rain in the metro area. Three inches might fall in Southland mountains, according to the National Weather Service.

Daytime highs Monday will be below 60.

Although skies over the L.A. basin should clear, cold wet air flowing down from the north will cause heavy precipitation in the Antelope Valley and Grapevine area last Monday and Tuesday, the NWS said. Snow levels could fall as low as 2,000 feet.

A foot or more of snow is likely at elevations greater than 6,000 feet. A NWS winter storm watch will be in effect Sunday night through Tuesday morning.

Tuesday should be dry and partly cloudy, with highs in the 60s. And no rain is expected on Wednesday.

The NWS said its computer models all agree that the second storm will be less-intense than first predicted. "It will rain Thursday, but the storm no longer looks like a huge rainmaker."

In the mountains, another foot of snow could fall in the higher elevations.

A third storm might hit next Saturday, the NWS said.

Any strong downpour in the fire-denuded San Gabriel Mountains could trigger slides in burn-area watersheds and the foothill communities below them, as evidenced by a half-hour storm that produced a mud flow in La Crescenta in mid-November.

Rain falling at a rate of an inch per hour could cause problems, NWS forecasters said. Pacoima Canyon, Big Tujunga Canyon, the Arroyo Seco, the West Fork of the San Gabriel River and Devils Canyon are considered to be the watershed most at risk.

Government crews have been working to clear a network of 29 catch basins in foothill areas in advance of the rain.

The Aug. 26 Station fire, the biggest in county history, burned about a third of the Angeles National Forest just north of the city, or 250 square miles, destroying 89 homes and more than two dozen commercial properties, and contributing to the deaths of two firefighters.