The ornamental design for a snowbrush, as shown and described.
FIG. 1 is a perspective view of a snow brush showing my present design,
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left view thereof;
FIG. 5 is a right view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view.
The tips of the individual strands that make up the bristle tufts are omitted within the bounds of each of the round tufts in FIG. 3 for ease of illustration.