BEFORE TAKEOFF, THE PLT WAS ADZD OF AN APCHG COLD FRONT IN THE FLORIDA PANHANDLE AS WELL AS A FORECAST OF HVY THUNDER- STORM ACTIVITY IN THE AREA OF PENSACOLA. EN ROUTE, HE WAS PROVIDED VFR FLT FOLLOWING FROM PENSACOLA APCH CTL WHILE CRUISING AT 6500 FT. OTHER FLTS THAT WERE OPERATING IN THE AREA AT LOWER ALTITUDE WERE DEVIATING AROUND WX TO REMAIN IN VFR CONDS. AT ABOUT 1214 CST, THE ACFT ENTERED A RAPID DSCNT. SUBSEQUENTLY, AN INFLT BREAKUP OF THE ACFT OCCURRED & WRECKAGE WAS SCATTERED OVER A 1735 FT AREA. WITNESSES RPRTD THAT JUST BEFORE IMPACT, THEY HEARD THE ENG ROARING IN THE CLOUDS. THEY RPRTD THE ACFT CAME OUT OF A CLOUD BASE & SHED ITS WINGS & TAIL BEFORE CRASHING. THEY ALSO RPRTD LOW CLOUDSIN THE VICINITY WITH GUSTY SURFACE WINDS & RAIN. AN EXAM REVEALED THE WINGS & TAIL SURFACES HAD SEPD IN OVERLOAD. NO PRE-ACDNT FAILURE, MALFUNCTION OR FATIGUE OF THE ACFT WAS FND. THE ACFT WAS ESTD TO BE 254 LBS OVER ITS MAX GROSS WT LIMIT & THE CG WAS ESTD TO BE .1 INCH BEHIND THE AFT LIMIT. THE PLT'S MED CERT WAS DATED 10/16/86.