The fast bowler is due to fly out to Pakistan on Wednesday ahead of his country's tour of Zimbabwe, but Lancashire are hopeful that the PCB will allow Junaid to play for them.
The 21-year-old has taken ten wickets at an economy of 5.59 in seven T20 matches for Lancashire.
"It's been a great experience playing for Lancashire and I hope that I have pleased the fans, players and coaching staff," said Junaid.
"I'll be leaving for Pakistan tomorrow [Wednesday] and will be attending the pre-Zimbabwe tour camp which starts next week in Lahore.
"We'll have to wait and see what is agreed between the PCB and Lancashire to see if I take part in Finals Day."
Lancashire are due to face Leicestershire in the semi-finals on T20 Finals Day at Edgbaston on Saturday, August 27.