Chernomaz played four seasons of junior hockey in the Western Hockey League (WHL) for the Saskatoon Blades and Victoria Cougars between 1979 and 1983. He scored 113 points in 1980–81 for the Cougars in the regular season. Chernomaz added 26 more in 15 playoff games, the fifth best total in the WHL, as Victoria defeated the Calgary Wranglers in the league championship final to win the President's Cup. The Colorado Rockies selected him with their second round selection, 26th overall, at the 1981 NHL Entry Draft, and he made his NHL debut in 1981–82, appearing in two games during a brief recall from Victoria. His NHL debut came on November 11, 1981, against the Montreal Canadiens. Chernomaz' best WHL season came in 1982–83 when he recorded 124 points in 64 games and was named a league all-star.