Your T Spine is very important when it comes to being in any upright position while lifting weights. Whether it is the front squat, clean, snatch, or even the strict press, having good mobility in your upper back will help you be in better positions for these movements. Below are two mobilizations you can do to help improve these areas.
1) Foam Roller Extension: Lie down on the foam roller with it resting horizontally across your back. Just below your shoulders. You will want to keep your feet and butt on the ground as your extend back. Try to wrap the foam roller with your back. The key is to not let your neck hang back because you will not be targeting your back at this point.
2) Back Rotation: In a seated position, cross your arms on your shoulders and point your elbows forward. Without moving your head, try and twist to each side as far as possible. Repeat for 10 repetitions per side.