Pounding rains, heavy snow: It’s shaping up as another wintry week in Northern California. A significant storm poured into the region Tuesday, the first stage of an extended wet period that’s expected to continue through Friday and possibly into the weekend. “It’s a pretty good, wet five or six days or so,” said Mike Kochasic of the National Weather Service in Sacramento. After brief overnight drizzles, the rains started falling in earnest early Tuesday. Temperatures were warm at first, and motorists heading over the Sierra Nevada found themselves dealing with raindrops instead of snow.