Complex sentence: Storms moving from the Pacific Northwest can bring rain and in some places even snow--more often, the rain shadow created by the Sierra Nevada as well as mountain ranges within the desert such as the Spring Mountains bring only clouds and wind.
Split into simpler sentences: Storms moving from the Pacific Northwest can bring rain and in some places even snow. More often, the rain shadow created by the Sierra Nevada as well as mountain ranges within the desert such as the Spring Mountains, bring only clouds and wind.