The airplane was substantially damaged at approximately 1840 Pacific time when it departed the runway during landing roll. The airline transport pilot, airline transport second pilot, and their six passengers were not injured. Visual conditions prevailed. The pilot reported the airplane rotated 90 degrees left after touchdown and continued until the aircraft departed the runway and the nose gear failed. The pilot said he was told that there was three-quarters of an inch of snow on the runway, and the wind was 80 degrees left quarterly at 19, gusting to 29 knots. After landing, he discovered that the runway had 2 inches of slush on it.
