The win is critical for the Griffons' (13-13, 6-6) MIAA Tournament hopes with four games remaining. MWSU entered the day seventh in the conference with the top eight finishers earning a berth.
The Bearcats (9-15, 3-9) remain 11th in the MIAA with the loss.
Kelsey Olion led the Griffons with 15 kills, while Erica Rottinghaus chipped in another 13. Lindsey Partridge posted a career-high seven blocks.
Abby Graves had a team-hight 12 kills for Northwest, while Shelby Duren added 11.