Which procedure is necessary when casting a tire impression in snow?

Spraying the impression with snow print wax is the correct procedure when casting a tire impression in snow. This is essential because the wax helps to solidify the impression and preserves the fine details. Snow can easily collapse or become distorted due to temperature changes or disturbances from wind or foot traffic. By applying snow print wax, the impression can retain its shape, allowing for a more accurate and detailed cast to be made afterward.

Using this spray encapsulates the details of the impression before any casting material is applied, which ensures that the final cast captures all the relevant features needed for forensic analysis. This method is particularly effective because it adheres to the snow surface, providing a stable base for subsequent casting.