Zoom climb
Nobody knows what is going to happen when an a/c enters a thunderstorm. No one.
If a strong enough updraft occurs it could push the plane up at 7000 fpm at the same time sending the nose down thus possibly causing nose up trim.
In addition no one knows for sure what the airplane will do when it is in a deep stall.
One thing i know, it is difficult to fly an out of control plane with trim alone.