A cold Pacific storm out of the Gulf of Alaska bore down on the Southland today and was expected to generate rain from late this afternoon through Wednesday, creating perilous driving conditions and raising some fears of mud slides down slopes denuded by wildfire.
The first wave of rain will be light to moderate and start spreading across the region late this afternoon, with a chance of residual showers on north-facing mountain slopes Tuesday morning, according to a National Weather Service advisory.
"Most areas are expected to see three to four hours of rain with the initial front," it said, adding that the snow level will initially be between 5,000 and 5,500 feet, dipping to 4,500 feet on north-facing slopes by Tuesday morning.
Conditions will include southwest winds gusting at more than 40 miles per hour in the Southland's mountains and the Antelope Valley this afternoon through tonight, according to the NWS.
A lull in the rain is expected Tuesday, followed by a wave of rain Tuesday afternoon and evening, lasting into Wednesday, NWS forecasters said. Because of cold air aloft, that second band of rain will be "more showery" than the first and could include brief and heavy downpours accompanied by small hail, they said.
A weaker storm system is expected late in the week, forecasters said.
The NWS forecast largely partly cloudy skies today and highs of 50 on Mount Wilson; 61 in Avalon; 63 in Lancaster; 64 in Palmdale, Newport Beach and Saugus; 65 at LAX, Long Beach, Burbank and San Gabriel; 66 in Pasadena; 67 in downtown L.A. and Woodland Hills; and 68 in Anaheim. Highs will be in the low to mid 60s much of this week.
From today through Wednesday, the storm is expected to generate between a quarter and three quarters of an inch of rain, with 1 inch possible across southwest-facing mountain slopes and near the sites of any thunderstorms, they said.
From Tuesday night into Wednesday morning, the snow level is expected to drop to between 4,000 and 4,500 feet, meaning snow could affect travel on Interstate 5 near The Grapevine, the advisory warned, adding that between 3 and 6 inches of snow are expected above 5,000 feet from tonight through Wednesday.
Residents of burn areas should monitor NWS forecasts to keep track of warnings of minor mud and debris flows, and "people planning to travel into the mountains should be prepared for winter-weather driving conditions," according to an NWS advisory.
--City News Service