Posted for "Mark & Lisa" <marknlisa@hometel.com>:

 Giff,
 
 Maneuvering speed is intended to protect the aircraft from a theoretical
 maximum gust.  There is no way to tell if the gusts encountered within a
 given thunderstrom conform to the theory.
 
 Slowing to maneuvering speed will increase your (and your aircraft's)
 chances of survival, but is by no means a guarantee.  Best bet?  Avoid the
 boomers.
 
 Mark & Lisa Sletten
 Legacy FG N828LM
 http://www.legacyfgbuilder.com