Showers will douse the Southland on Thursday, Friday and Saturday, thanks to a cold-weather system likely to generate snow flurries at the 3,000-foot level and cause temperatures to drop up to 20 degrees below normal, forecasters said.
"A cold upper-level trough of low pressure will affect southwestern California with scattered showers and mountain snow showers Thursday night into Saturday," according to a National Weather Service advisory.
"Light showers ahead of this weather system are expected to affect portions of Ventura and Los Angeles counties on Thursday. More showers are expected to move into the region Thursday night, with scattered showers persisting into Friday morning."
Rainfall amounts are difficult to forecast with precision because of the showery nature of the expected precipitation, according to NWS forecasters, who said they generally expect a quarter-inch of rain or less but that up to a third of an inch is possible.
The snow level will be at between 5,500 and 6,500 feet tonight but drop to between 4,000 and 4,500 feet during the day Friday and to between 3,000 and 3,500 feet Friday night, according to the advisory.
"Some light accumulating snow perhaps up to an inch or two will be possible in the mountains above 3,500 feet through early Saturday," according to the advisory.
"This could affect travel along Interstate 5... including over The Grapevine, especially Friday night and early Saturday."
There may also be snow showers in the foothills above the Antelope Valley, but without accumulation.
The weather service warned motorists planning to travel through mountain areas between tonight and early Saturday to be prepared for snow showers, reduced visibility, icy roads and sharply colder temperatures.
As a result of the cold front, temperatures will be falling sharply—"as much as 10 to 20 degrees below normal by Friday," according to an NWS advisory.
The NWS forecast highs today of 52 on Mount Wilson; 60 in Saugus; 61 in Avalon, Burbank, and San Gabriel; 62 in Pasadena, Woodland Hills and downtown L.A.; 63 in Lancaster, Long Beach and at at LAX; 64 in Palmdale; 67 in Newport Beach; and 68 in Anaheim.
A return to sunny weather and a sharp temperature hike are expected Sunday.