Heavy snow is likely to start the week in the San Bernardino and Riverside county mountains. Winter Weather Advisories have been issued for up to 5" of additional snowfall throughout the day. A storm system has been moving into the Southwest, bringing areas of rain and thunderstorms. As the moisture moves into the mountains and higher elevations, it hits the cold air, producing pockets of heavy snow. By tonight (Monday), the system will move to the east and south, bringing an end to the precipitation in Southern California.