Yes, it’s officially spring and April already, but Mother Nature isn’t finished with winter quite yet. A new storm system heading to Central California will bring more rain to the Valley and snow to the Sierra mountains and foothills later this week.

Snow could fall as low as 3,000 feet on Thursday, National Weather Service forecaster Victor Proton said Monday.

And that’s coming on the heels of above-normal temperatures that could push Wednesday’s high to 80 degrees, he said.

This week’s pattern of sunshine and storms continue the yo-yoing weather that have kept Valley residents alternating between T-shirts and fleece for the past few weeks.

Why is it happening? Proton describes it in oceanic terms, with periods of calmer waves followed by storm-tossed whitecaps slapping the shore. But in this case the waves are happening far above our heads, as ridges of high pressure bringing warmer weather are followed by troughs of low pressure bringing colder weather and precipitation.

This year the ridges and troughs have been more extreme than usual, he said.

From Siberia to Valley

And if the new band of cold later this week feels particularly cold, there’s a reason: It’s coming to us from Siberia, sweeping south and west until it crosses the west coast of California, Proton said.

Thursday and Friday’s precipitation won’t be as heavy as the last couple of storms. The forecast is for two-tenths of an inch of rain at most in the Valley. But because of the cold wave, snow levels will drop from 7,200 feet Wednesday afternoon to 3,000 feet by Thursday afternoon, he said.

Foothills residents could get trace amounts to an inch of snow, with 6 to 10 inches falling above 6,500 feet, Proton said.

Getting snow in the foothills this late in the season is “kind of a novelty,” he said.

What’s ahead: the long-range forecast is for cooler, wetter weather to continue for the next two weeks, Proton said.