The ornamental design for a snow plow headlamp, as shown and described.
FIG. 1 is a top front right perspective view of my new, original and ornamental design for a snow plow headlamp.
FIG. 2 is a front view thereof.
FIG. 3 is a left side view thereof.
FIG. 4 is a right side view thereof.
FIG. 5 is a top view thereof; and,
FIG. 6 is a bottom view thereof.
The broken lines illustrate environment and/or unclaimed boundaries and/or unclaimed features, are for illustrative purposes only, and form no part of the claimed design.