A Pacific storm will bring Southern California rain, snow, high winds and possibly thunderstorms beginning this afternoon and lasting through Saturday, forecasters said.
Along with with some precipitation, which is not expected to last beyond Saturday, the storm will trigger a drop in temperatures until Monday, according to a National Weather Service forecast.
NWS forecasters also issued a warning to residents living in the San Gabriel Valley beneath areas denuded by the 1,992-acre Colby Fire in January, urging them to monitor the situation. There is a potential for heavy downpours tonight, and these could unleash flows of mud and debris, they said.
The NWS said a fast-moving cold front would spread rain along the Central Coast by mid-day today, move south and reach Ventura and Los Angeles counties by evening, triggering showers that will linger into Saturday morning.
The showers could extend into Saturday afternoon on north-facing mountain slopes and stretch into early Sunday morning, according to the NWS.
Most areas will experience three or four hours of rain as a result of the cold front’s initial Southern California foray before the precipitation turns to showers. There also will be a “slight” chance of thunderstorms in San Luis Obispo and Santa Barbara counties, according to the NWS, which said any thunderstorm will have the potential to pack heavy rain and small hail.
On the whole, the rain’s impact may be negligible in the Greater L.A. area, although the latest forecasts envisioned more rain than initially projected.
Rainfall amounts from Friday afternoon through Saturday are now expected to range between three quarters of an inch to 1 1/2 inches along the Central Coast, with up to two inches in northwestern San Luis Obispo County, but otherwise, most areas can expect between a quarter-inch and three quarters of an inch, with up to 1 inch in the San Gabriel Mountains, according to a NWS statement.
The rains will be the first to fall over a wide area this season, which starts around Oct. 1, and will combine with months of oil buildup to make paved surfaces dangerously slick, NWS forecasters warned, urging motorists to use extra caution.
The snow level will be above 7,500 feet through Friday evening, then fall to between 6,500 and 7,000 feet by late Friday night and to between 6,000 and 6,500 feet by Saturday morning, the statement said.
Between 2 and 4 inches of snow may accumulate in the San Gabriels at the 7,000-foot level and higher and 1 inch or less between 6,000 and 7,000 feet.
The combination of snow and gusty high winds could prompt forecasters to issue a winter weather advisory for the San Gabriels.
Also expected as a result of this storm are strong winds. Southwest winds gusting to between 35 and 45 miles per hour are expected in the mountains of Ventura and Los Angeles counties and in the Antelope Valley Friday afternoon and evening, NWS forecasters said. By Saturday morning, the winds will turn to the northwest, with gusts of between 40 and 45 mph possible in the mountains and the Antelope Valley.
The NWS forecast drizzle this morning and temperature highs of 66 degrees on Mount Wilson; 67 in Avalon 70 at LAX; 69 San Clemente; 71 in Laguna Niguel, Palmdale and Lancaster; 72 in Long Beach, Newport Beach, Yorba Linda, Mission Viejo and downtown L.A.; 73 in Anaheim, Fullerton, Pasadena and Burbank; 74 in Irvine and San Gabriel; and 75 in Woodland Hills and Saugus.
Saturday’s temperatures will climb down another 5 degrees or so, Sunday’s will revert to today’s levels, and Monday’s will represent a warming trend. Downtown L.A., for example, is forecast to reach 72 today, 67 Saturday, 72 Sunday, 75 Monday and 80 on Tuesday. The forecast also envisions the return of sunny skies on Sunday.