SAN FRANCISCO (AP) — A new Pacific storm heading toward California is expected overnight, spreading rain and mountain snow in the northern half of the state before moving south.

The National Weather Service says the system will be a contrast to Thursday’s tranquil conditions.

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Forecasters say the rainfall rates could be moderate to heavy at times.

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In the Sierra Nevada, snow levels will start out above 8,000 feet (2,438 meters) on Friday, then lower to around 7,000 feet (2,133 meters) Friday night and Saturday.

Snow accumulations above 8,000 feet (2,438 meters) could range up to 12 inches (30.5 centimeters), impacting travel through the mountain range.

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The storm will be weak when it arrives in Southern California later Friday through Saturday. Forecasters say Monday and Tuesday will be windy with a chance of showers.