Mowatt has sat out the Reds' last two games against Charlton Athletic and Carlisle United after coming off with a side strain in the second half of the South Yorkshire derby at Sheffield Wednesday on August 10.
There were some concerns that the former Leeds United schemer, highly influential in last season's promotion campaign, could be out for a spell of games, but those fears seem to have been allayed.
Stern, who says that the Reds have no other injury concerns, said: "He does have a chance to play tomorrow.
"He is being assessed at the minute and we are going to see how he performs in training and how fit he feels and we are going to make a decision after training after all the opinions from medical staff and coaching staff."
Barnsley boast a five-match unbeaten run at St Andrew's, heading into tomorrow's trip to the second city, with the Reds having won three times on their last four visits.
Stern said: "We have a good record at Birmingham, but it is a totally different game than previous games.
"For them, they will be hoping to show a different performance than the weekend and we hope we can keep our good record, but it is a new game."