Armstrong now has seven goals in seven games for the club, following a brace against Blackpool in the side's last game.
And Mowbray is sure that Armstrong's parent club are watching happily as the youngster makes progress on loan.
Mowbray said to the Lancashire Telegraph: "I don't know what else to say about Adam, to be honest.
"He's a young lad learning the game, and I'm sure Rafa Benitez will see the video clips of all of the goals he's scoring.
"He scored a fantastic goal against Wigan and two more brilliant goals against Blackpool.
"Goals like his second one are never easy but he kept it down and put it into the corner.
"He also works extraordinarily hard, it's not as though he's a striker who just stands there.
"I'll look forward to him scoring many more goals."