THE INTENDED 45 MINUTE SIGHT SEEING HELICOPTER FLIGHT DEPARTED THE AIRPORT AT ABOUT 1032 HOURS. ADVERSE WEATHER CONDITIONS INCLUDING THUNDERSTORMS, RAIN SHOWERS, AND POOR VISIBILITY WERE REPORTED IN THE VICINITY OF THE ACCIDENT SITE THROUGHOUT THE MORNING. THE ACCIDENT AIRCRAFT PILOT HAD A RADIO CONVERSATION WITH ANOTHER SIGHT SEEING TOUR PILOT BETWEEN 1055 HOURS AND ABOUT 1100 HOURS. THIS PILOT CONTACTED THE ACCIDENT AIRCRAFT PILOT TO TRY TO DETERMINE WHICH ROUTE SHE SHOULD TAKE TO AVOID THE ADVERSE WEATHER. SHE REPORTED THE ACCIDENT PILOT'S LAST CONVERSATION WITH HER AS 'DON'T COME DOWN THIS WAY, THE WEATHER IS GETTING REAL BAD.' A WITNESS LOCATED ON THE GROUND IN THE VICINITY OF THE ACCIDENT REPORTED RAIN SHOWERS AND MOUNTAIN OBSCURATION AT ABOUT THE TIME OF THE ACCIDENT. HE FURTHER STATED THAT HE SAW A BLUE AND WHITE HELICOPTER FLYING IN AND OUT OF THE CLOUDS AND HE COULD NOT UNDERSTAND WHY A HELICOPTER WOULD BE FLYING SO CLOSE TO THE MOUNTAINS IN CONSIDERATION OF THE ADVERSE WEATHER. EXAMINATION OF THE WRECKAGE SHOWED THE HELICOPTER IMPACTED A 30 DEGREE SLOPE IN A LEVEL 15 DEGREE RIGHT BANK. WRECKAGE AND DEBRIS WERE SCATTERED OVER A DISTANCE OF ABOUT 175 FEET FROM THE INITIAL IMPACT LOCATION.