Tioga Road (continuation of Hwy 120 through the park) is closed; it usually opens in late May or June (snowpack is higher than average, though). Check current road conditions by calling 209/372-0200 https://www.nps.gov/yose/planyourvisit/tiogaopen.htm
https://www.nps.gov/yose/planyourvisit/tiogaopen.htm