THE PILOT-IN-COMMAND'S FAILURE TO MAINTAIN AN ADEQUATE ALTITUDE IN MOUNTAINOUS TERRAIN, IN MODERATE-TO-SEVERE TURBULENT CONDITIONS, WHICH RESULTED IN A LOSS OF CONTROL. IN ADDITION, THE PILOT WAS PHYSICALLY IMPAIRED DUE TO ALCOHOL. FACTORS CONTRIBUTING TO THE ACCIDENT WERE: THE PILOT'S FAILURE TO OBTAIN CURRENT OR FORECAST WEATHER FOR THE AREA, MOUNTAINOUS TERRAIN, AND THE EXISTING TURBULENT AND WINDY CONDITIONS.