San Francisco will get a sprinkling of rain starting Saturday morning, but the storm system moving in from the north will be bringing the first major snowfall of the winter season to the Sierra.

Weekenders with ski rentals and the like are being told to change their plans if they were planning on doing any driving Saturday, or maybe even skiing for that matter. Parts of the Sierra Nevada mountains including the Tahoe area will be seeing significant snowfall, and a Winter Storm Warning will be in effect from 4 a.m. Saturday to 6 a.m. Sunday for much of the region.

As you can see from the animation below, the Bay Area is on the western edge of the system, and as such we'll only be seeing light rain, while the majority of the precipitation will be hitting the mountains.

That could mean that Sunday will be an amazing ski day, but if you aren't headed up there already today, you may be missing it, because Saturday will be no day for driving around Lake Tahoe, and blizzard conditions are likely on I-80.

"Saturday is going to be a pretty treacherous day for travel," says Dylan Flynn, a National Weather Service forecaster, speaking to SFGate. "There are certainly going to be whiteout conditions on some of the roads and over passes. Anyway who wants to travel up there should consider going today [Friday] instead of tomorrow [Saturday]."

Some light snow is expected around the Tahoe area on Friday night, ahead of the actual storm. The bulk of the snowfall is expected in the Sierra between 10 a.m. and 10 p.m. Saturday, with gusty winds up to 50 miles per hour, and accumulation of around 3 inches per hour.

For us in San Francisco, you should get out for a walk today, because while the sun will be back out on Sunday, it's expected to be a fair bit chillier for the next week.

Photo: Tom Milkovic