A cold Pacific storm out of the Gulf of Alaska moved toward Southern California Monday and was expected to generate rain from late afternoon through Wednesday.
The first wave of rain will be light to moderate and spread across the region later Monday with the most significant rainfall after 10 p.m. Showers on north-facing mountain slopes migth continue into Tuesday morning, according to a National Weather Service advisory.
"Finally, some measurable rainfall," said NBC4 meteorologist Crystal Egger. "Most of the rain will fall overnight while we're sleeping. Roads will be slick by the (Tuesday) morning commute."
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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, forecasters said.
Most areas are forecast to receive three to four hours of rain from the intial front, according to the National Weather Service. Snow levels 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 mph in SoCal mountains and the Antelope Valley Monday afternoon through Monday night, according to the NWS.
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In the Antelope Valley, a wind advisory will be in effect from 1 p.m. until 9 p.m. Winds of between 25 and 35 mph gusting to 50 mph are expected, which could affect traffic on the Antelope Valley (14) Freeway and Pearblossom Highway, state Route 138, forecasters said. Motorists should be prepared for gusty crosswinds, and blowing sand and dust in the Antelope Valley could reduce visibility to a quarter mile or less, forecasters said.
- Running Dry: California Drought Coverage
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.
- Updates: Severe Weather Alerts
The storms come amid long-term drought conditions in California. The first significant storms in months brought rain to California in late February and early March, but persistent dry conditions prevailed since then, reducing the rainfall's benefits for the drought-stricken region.
Since December, 4.47 inches of precipitation have been reported in California. The average for that period is 11.73, according to the National Climatic Data Center. The state has received 7.53 inches of precipitation since June, about 9 inches below the average for that nine-month period.
The February-March storms led to mudflows in the San Gabriel Valley foothill communities east of Los Angeles. Homeowners who live below the Colby Fire burn area faced evacuation orders, then returned home to find their backyards covered with mud that came down from the hillside.
Minor debris flows are possible in the same areas during this week's storms.
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.