At about 1230 Mountain time, the airplane impacted terrain under unknown circumstances, killing the non-Instrument rated Commercial pilot and sole occupant. The airplane sustained substantial damage. Instrument meteorological conditions prevailed at the accident site. The flight was receiving VFR flight-following services; at about 1119, the controller advised the pilot of a storm system in the Salt Lake Valley and to the south. The pilot acknowledged receiving the information. At about 1138, the pilot was again advised of deteriorating weather conditions along his route of flight. About 1151, the pilot reported he was following I-80 south and, if necessary, would turn around and land at Fort Bridger, Wyo. At 1209, relaying through another aircraft, the pilot was informed that radar contact was lost. At 1229, the airplane was observed on radar for one or two hits. Further attempts were made to contact the airplane, and no reply was received. At 1230, a weather observation approximately 50 miles north-northeast of the accident site included wind from 240 at six knots, visibility 2 statute miles in snow and mist, scattered clouds at 600 feet, broken clouds at 1000 feet and an overcast at 3100 feet.