A cold Pacific storm is likely to bring widespread rain and mountain snow to Southern California late Sunday into Monday, the National Weather Service said.
The low system is expected to draw in a plume of moisture from the Pacific that could produce significant precipitation on Sunday and Monday, said Eric Boldt, a meteorologist with the National Weather Service in Oxnard. The heaviest rainfall is expected on south- and southwest-facing slopes in the mountains and foothills, enhanced by low-level southerly flow.
Rain will be widespread, likely over the entire area Sunday night, with the most intense rain falling between midnight Sunday and noon Monday.
Periods of moderate to locally heavy rain could result in totals of a half-inch to an inch for the coast and valleys, and 2 to 3 inches in the mountains. Snow levels will be 4,500 to 5,500 feet, with accumulations of 6 to 12 inches above 6,000 feet. Hazardous winter driving conditions because of snow are likely at higher elevations, and mountain resorts could potentially receive significant snow Sunday into Monday.
While flooding is possible at times on roadways, the system does not appear to be sufficiently intense to cause debris flows in recent burn areas.
Gusty southerly winds will accompany the system, especially in the mountains, and temperatures will remain well below normal through next week.
A threat of scattered showers will continue Tuesday through Friday with a slight chance of afternoon thunderstorms.
If downtown Los Angeles gets close to an inch of rain with this system, it could equal the April average of 0.91 inches. Any rain would be welcome where three-quarters of the state is at least abnormally dry or in drought. The most recent U.S. Drought Monitor data released on Thursday shows no change from last week, with only a quarter of the state drought free. The drought-free portions include most of San Diego County, all of Imperial County, western Riverside and San Bernardino counties and southeastern Inyo County. There is a section in northern Siskiyou County near the Oregon border that is classified as being in severe drought.