As others have said thunderstorms might have been involved but if the in-flight breakup was caused by the thunderstorm itself, the probable cause would have been something like "pilot continued flight into area of thunderstorm activity".
"Pilot Induced" in this case means that the investigators believe that the pilot became disoriented and placed the aircraft in an abnormal attitude, and then overstressed the control surfaces in an attempt to recover.
This is, unfortunately, a fairly common scenario in general aviation. Since the pilot did not have an instrument rating, and flew into IMC (Instrument Meteorological Conditions, ie very low visibility) this is a likely scenario. This could have been clouds with or without thunderstorms. Thunderstorms would have made the problem worse, as the turbulence would have compounded an attitude control problem but the weather report does not mention thunderstorms (might not have been 100% accurate). It is also possible for this to occur on a dark night, even without the presence of visible moisture (that's what happened to JFK junior). This could also happen to a qualified instrument rated pilot if he suffered a failure of critical flight instruments.
The industry term for this scenario is "graveyard spiral". General aviation has come a long way since the 1970's in educating pilots about the risks involved for non-instrument pilots in adverse weather. Unfortunately these were lessons learned the hard way, by too many good folks.
Last edited by rickair7777; 11-23-2010 at 06:30 AM.