Southern Californians can expect cooler temperatures and windy weather over the weekend because of a big change in the weather pattern several hundred miles off the coast.
Meteorologist Dan Bowman of WeatherData Inc., which provides forecasts for The Times, said Thursday that a high pressure ridge off British Columbia is going to cause winds aloft to blow from the north.
And, as a result, he said, the winds will steer a "pretty strong" storm system across southern Nevada, and that is going to bring colder temperatures and north winds to Southern California.
Gusts of 40 to 50 m.p.h. are expected in the deserts, mountains and below the canyons Sunday.
"People are going to feel the colder temperatures," Bowman said. "It looks like the temperature will drop into the high 50s and low 60s through Monday and Tuesday, but the chance of rain is real slim."
The weather is expected to start cooling off Saturday from a predicted high in the upper 70s or low 80s at the Los Angeles Civic Center today. The downtown high on Thursday was 78 degrees, nine degrees warmer than normal for the date.
The relative humidity ranged from 86% to 36%.
At the beach, occasional large swells generated by a strong disturbance dying in the Gulf of Alaska still slammed into jetties and wharfs, but generally the surf ranged mostly from three to five feet from Santa Barbara to San Diego.
The National Weather Service issued a freeze warning for all agricultural areas of Southern California for Saturday, Sunday and Monday nights. Growers in areas protected from the wind were advised to expect temperatures in the low 20s.
The weather service told Arizona residents that they can expect a strong storm, which was developing over the Great Basin on Thursday, to bring increasing clouds and winds Saturday and heavy rain and snow over the northern portions of the state Sunday.
Campers and backpackers were warned to plan to be out of the backcountry by Saturday evening at the latest. And, highway travelers also were advised to complete their trips Saturday, if possible.