A cold low-pressure system will move across the Southland today, generating showers, high surf, blizzard conditions in mountain areas and strong Santa Ana winds through Friday, according to the National Weather Service.
NWS forecasters said there is a slight chance of showers this morning, but a near-certainty of showers this afternoon. There is also a 20 percent chance of showers and thunderstorms this evening, but Thursday is expected to be sunny.
A winter weather advisory, indicating that snow and blowing snow will create difficult travel conditions, will be in force in the Los Angeles County portion of the San Gabriel mountains from noon today until 3 a.m. Thursday. Once it expires, it will be replaced by a high wind watch, which will be in force until Friday morning in the San Gabriels as well as the Santa Monica range.
Between two and four inches of snow was expected to accumulate above the 4,500-foot level in the San Gabriels today, according to an NWS advisory. There is also a slight chance of a thunderstorm in the mountains this afternoon and again tonight, it said.
Northwest winds of between 20 and 30 miles per hour gusting to 45 mph were expected in mountain areas today, reducing visibility to a quarter-mile or less because of blowing snow, according to the NWS.
"Snow, blowing snow and gusty winds will make for dangerous travel into and through the mountains," the NWS warned in an advisory. "Snow may affect travel on Interstate 5 through The Grapevine later today into tonight."
Additionally, "roads will become snow-packed and icy," it said. "Use caution while driving."
Strong winds also were expected at lower elevations. A wind advisory, indicating that winds of 35 mph or greater are expected, will be in effect from noon today until 9 p.m. tonight along the coast, in metropolitan Los Angeles, on Santa Catalina Island and in the Antelope Valley.
In Orange County, the wind advisory will be in force from 1 p.m. to 7 p.m. today, and a more serious high wind watch will take effect late tonight, lasting through Friday afternoon.
Even stronger winds than today's were on tap for later in the week.
"Later tonight, strong surface high pressure will build into Nevada and combine with northeasterly winds wrapping around an upper low to the east of the area," the NWS said in an advisory.
"This combination will produce a moderate to strong Santa Ana wind event over much of Los Angeles and Ventura counties" Thursday and Friday, including 60-mph gusts in the mountains, it said.
Along the coast, meanwhile, above-normal surf will be evident at west-and northwest-facing beaches today and tonight, and "there is a high risk of rip currents on all area beaches," according to an NWS advisory.
Temperatures were expected to remain on the cool side today but rise sharply Thursday, when sunny skies are expected.
The NWS forecast highs of 41 today, 53 Thursday on Mount Wilson; 52 today, 60 Thursday in Palmdale and Lancaster; 56 today, 66 Thursday in Saugus; 56 today, 67 Thursday in Avalon; 56 today, 70 Thursday in Anaheim; 57 today, 66 Thursday in Newport Beach; 57 today, 70 Thursday in Pasadena, San Gabriel and Burbank; 58 today, 69 Thursday in Woodland Hills; 59 today, 69 Thursday at LAX; and 59 today, 71 Thursday in downtown L.A. and Long Beach.
Temperatures will be even higher Friday but climb down a few degrees