Changes are on the way for the West Coast as a storm system will tap into an atmospheric river by mid-week, bringing heavy rain and the potential for flooding and landslides.

While the WeatherRadar is showing light rain for parts of the Pacific Northwest on Tuesday, the main event won't arrive for another 24 hours. On Wednesday a storm system moves in off the Pacific, bringing heavy rain and high-elevation snowfall to the West Coast.

Rain will spread across much of the West Coast on Wednesday, stretching from Seattle to San Francisco. Southern California will start to see downpours on Thursday morning. It will be a wet morning commute on Thursday in Los Angeles and San Diego. Northern California and the Pacific Northwest will stay wet on Thursday.

While there will be some mountain snow with this system, rain is the primary concern on Wednesday and Thursday, especially in southern California, where heavy rain led to flooding and landslides last week. On Wednesday, the Weather Prediction Center has issued a slight risk of excessive rainfall, a level two out of four, for northern California. A slight risk is in place for southern California on Thursday, including the Los Angeles metro.

As we head into Friday and Saturday, rain and mountain snow will continue for parts of the West and will spread east into the Rockies.

Rain and snow totals will vary through the end of the week. Northern California will see 3 inches or more of rain through Friday, with southern California picking up 1-3 inches. The highest peaks in the Sierra will see a foot to up to 18 inches of snow. Lower elevations in the mountains will see more modest accumulations.