THE PILOT-IN-COMMAND WAS UNFAMILIAR WITH THE PASS AND WAS ADVISED THAT THE WEATHER IN THE PASS WAS VERY POOR. HE STATED HE WOULD GO TAKE A LOOK. THE PASS MAKES AN 'S' TURN AT THE TOP IN LESS THAN 1 MILE OF DISTANCE. THE AIRPLANE IMPACTED THE SIDE OF THE MOUNTAIN NEAR THE MIDDLE OF THE 'S' TURN. WEATHER REPORTED BY ANOTHER PILOT 15 TO 20 MINUTES EARLIER INDICATED THE PASS WAS CLOSED.