But, the gusty part will get you! 12 to 15 sustained will be fine. But, if it's gusting to 20? No way--not with a trainer for sure! Better safe than sorry. I know of one good instructor who lost a plane because higher level winds were stronger than on the ground. The strong winds unseated the wing, and it came to rest on top of the cabin, instead of in the saddle where it belongs. That changed the wing incidence so much that the plane couldn't be controlled. You're better off if it's a bolt on wing, but I still wouldn't tempt fate. Too expensive of a hobby!