1. Visiting Faculty, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061-0105 (corresponding author).
2. Associate Professor, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061-0105.
3. Professor, Research Institute for Hazards in Snowy Areas, Niigata Univ., Igarashi 2-8050, Niigata, Japan.
4. PhD Candidate, Research Institute for Hazards in Snowy Areas, Niigata Univ., Igarashi 2-8050, Niigata, Japan.