For Ryan, the goal which came off a rebound, was his 11th of the season.
Notre Dame (30-5-3) will face Michigan in Saturday night's championship game at Joe Louis Arena. Northern (18-17-5) will play Alaska in the consolation game on Saturday afternoon.
Kyle Lawson also scored for the Irish and Jordan Pearce
made 21 saves.
Mark Olver scored for NMU and Brian Stewart stopped 34 shots.
Olver had just tied the game with his 17th goal with 1:23 left.