An atmospheric river taking shape over the Pacific could bring rain and mountain snow along Interstate 80 and other Sierra routes late this week, according to the National Weather Service.

Forecasters in Sacramento said confidence continues to rise in a “potent atmospheric river event” developing between Friday and Monday. Snow levels begin above 8,000 feet Friday and drop to near pass level, including Donner, later in the weekend.

The storm is being driven by a deepening trough from the Gulf of Alaska, which may funnel subtropical moisture directly into Northern California.

The National Weather Service in Reno said the storm track may stay farther north, which would limit heavier precipitation in western Nevada but could still produce strong winds, valley rain and snow over the highest

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