The ornamental design for a snowbrush, as shown and described.
FIG. 1 is perspective view of the snow brush;
FIG. 2 is a first side view of the snow brush of FIG. 1;
FIG. 3 is a bottom view of the snow brush of FIG. 1;
FIG. 4 is a top view of the snow brush of FIG. 1;
FIG. 5 is a second side view of the snow brush of FIG. 1;
FIG. 6 is a back view of the snow brush of FIG. 1; and,
FIG. 7 is a front view of the snow brush of FIG. 1.
The broken line showing of portions of a shaft is included for the purpose of illustrating environmental structure and forms no part of the claimed design.