The Patriots (27-2) used a crushing 22-to-6 run in the opening half to put the game away early, as senior Brittany King finished with her 11th double-double of the season.
After a King layup increased the Patriots' lead to 15-8 with 8:34 left, UT Tyler went on a rampage over the next seven minutes, going up 35-14 with 1:51 left in the half.
Obach and Jasmin Baskin would hit a pair of three-pointers in the closing minute of the first half, giving UT Tyler the commanding 41-18 lead at the break.
It would be much more of the same for the Pirates (15-13) in the second half, who would finish the game shooting just 40-percent.
UT Tyler would go up by as many as 32 points in the second half, cruising to an easy, 75-47 win over the Pirates.
For the game, the Patriots would shoot 47-percent, including 42-percent from beyond-the-arc, hitting 10 three-pointers in the victory. Southwestern shot 40 percent from the floor and 41 percent from three point range but just 40 percent from the charity stripe.
UT Tyler advances to the NCAA second-round and will face Texas Dallas on Sunday.