A cold weather system out of the Gulf of Alaska will generate showers Friday night, trigger a precipitous temperature drop and lower the snow level to around 3,000 feet.
The cold snap, which is forecast to last through Saturday, results from a cold upper-level trough of low pressure, according to the National Weather Service. Temperatures will be 10 to 20 degrees below normal, and highs in Orange County valley areas today will be in the 50s and low 60s, according to NWS forecasters.
Showers starting Friday afternoon will douse the region through Saturday morning, then taper off, forecasters said, adding they expect only a quarter of an inch of rain or less, although up to three inches is possible any area where a heavy shower occurs.
The snow level, around 5,000 feet at the start of the day, will drop to near 3,000 feet by late Friday, according to an NWS advisory. Only light accumulation is expected, although up to 3 inches is possible above 3,500 feet, especially on northern San Gabriel Mountains slopes in Los Angeles and Ventura counties.
``The snow should affect travel along Interstate 5 in northwestern Los Angeles County, including over The Grapevine, especially late tonight,'' according to the advisory. ``Motorists planning to travel into the mountains through Saturday should be prepared for the possibility of snow showers, reduced visibility, sharply colder temperatures and icy road conditions.''
On Saturday night, the skies will clear and a cold air mass will appear over the region, plunging overnight valley temperatures to between the mid 20s and low 30s, according to the NWS. Forecasters said conditions might warrant frost advisories or freeze warnings.
The NWS forecast highs Saturday of 65 in Seal Beach, 63 in Mission Viejo and Lake Forest, and 61 in San Clemente. Overnight lows throughout Orange County are expected to be in the mid to low 40s.
- City News Service Contributed to this report.