First, you work HARD to avoid the storm through proper weather planning and monitoring. This is something that isn't taught all that much at this point in formal instruction but should be. If you get caught out in high winds, you screwed up and some guys that have done this haven't survived the mistake. Dangerous, unstable weather needs to be avoided. Some information in this regard appears at:
http://fksa.org/showthread.php?t=69
If despite all precautions you get caught out and are concerned that you may be overpowered, NOT waiting until you are overpowered, simply Emergency Depower your kite. Don't wait, do it now and bailout or self-rescue using your adequate swimming ability, supplemented (slightly) by your impact vest. How you Emergency Depower will vary from kite to kite to some degree but I would never consider flying one in the first place without first understanding, then practicing this very basic step. Make sure your instructor will teach you how to self-rescue in your course. A good course will involve a thorough explanation, practice of Emergency Depowering followed by several actual Emergency Depowering exercises with no warning upon demand.