Turnbull, who made 21 appearances for Scarlets this season, has not played for his country since November 2012.
But with injuries in coach Warren Gatland's back row, the 26-year-old is set to get a chance to further his claim for a spot in the team.
Wales travel to South Africa to take on the Springboks twice this month and Turnbull, who will play for Cardiff Blues next season, is relishing being back in the fold.
"Fingers crossed I'll get an opportunity, it's been a long time since that game against Argentina," he said.
"It's been a long time out with injuries and things, but it's nice to be back involved in some form and hopefully I'll get a chance to play out there and show what I can do."
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