Patient Portal; Locations Southern Sierra Medical Clinic. Southern Sierra Medical Clinic About This Location. VIEW ALL PROVIDERS AT THIS LOCATION. View All. ... Address Southern Sierra Medical Clinic. 105 E. Sydnor Ridgecrest, CA 93555 (760) 446-6404 Get Directions. 1081 N China Lake Blvd, Ridgecrest, CA 93555. Careers; My Healthcare Portal ....