The Pacific Northwest has begun getting hit by an unusual series of winter storms that started on Friday and was expected to stretch into next week, while parts of California began to get pummeled with snow.

Areas around Seattle received four to six inches of snow during the city’s second bout of winter weather in the past week, a storm that is likely to stretch until late afternoon on Saturday, according to the National Weather Service. Meteorologists predict even more snow throughout the next week.

The storm that hit the area earlier this week dumped two and a half inches on Seattle-Tacoma International Airport and up to 12 inches on smaller cities outside Seattle.

This pattern of winter storms is rare for Seattle, said Cliff Mass, a professor of atmospheric sciences at the University of Washington. Heavy snow in Seattle requires an unlikely mixture of moisture and cold air, Professor Mass said, but the moisture from the Pacific Ocean tends to be relatively warm.