...Pacific storm system to affect southwestern California this afternoon through Saturday...
A cold upper level trough of low pressure and surface cold front will bring periods of Rain...Mountain snow...possible thunderstorms...and gusty winds to southwestern California this afternoon through Saturday.
A fast moving cold front will spread rain along the central coast this afternoon...then spread into Ventura and Los Angeles counties this evening. Showers will persist into Saturday morning across the region...with a chance of residual showers mainly on north facing mountain slopes from Saturday afternoon through early Sunday morning. Most areas are expected to see 3 to 4 hours of steady rain with the initial front...then turn showery as the front moves east. There will also be a slight chance of thunderstorms over San Luis Obispo and Santa Barbara counties tonight as colder air moves in aloft. Any thunderstorms would have the potential to bring brief heavy rain and small hail.
Rainfall amounts from this afternoon through Saturday are generally expected to range between three quarters of an inch to one and one half inches along the central coast...with higher amounts across northwestern San Luis Obispo County. Otherwise rainfall amounts of one quarter to three quarters of an inch can be expected for most areas...with local amounts up to one inch in the San Gabriel Mountains.
Snow levels will start out above 7500 feet through this afternoon then fall to 6000 to 6500 feet by Saturday morning. Most of the steady precipitation should be over before the snow levels lower significantly. Even so...1 to 3 inches of snow accumulation will be possible for the San Gabriel Mountains around 7000 feet and above...with an inch or less between 6000 and 7000 feet. With the expected snowfall combined with gusty winds...driving conditions in the mountains could be difficult tonight.
Southwest winds gusting to around 40 mph are also expected over the mountains of Ventura and Los Angeles counties and in the Antelope Valley this afternoon and tonight in advance of the front. Winds will turn northwest over the area by Saturday morning with gusts around 40 mph possible in the mountains and Antelope Valley.
Residents near the Colby burn area should monitor the latest National Weather Service forecasts and statements as the potential for locally heavy downpours tonight could bring the threat of minor mud and debris flows.
Since this will be the first widespread rain event in quite some time...roads will be extra slick due to months of oil buildup on paved surfaces. Motorists are urged to use extra caution in the rain. In addition...people planning to travel into the mountains should be prepared for winter weather driving conditions over the higher elevations.
Listen to NOAA Weather Radio or your local media for the latest updates on this storm system.