The ornamental design for a snowfence, as shown and described.
FIG. 1 is a front, perspective view of a snow fence, showing my new design;
FIG. 2 is a top, plan view thereof;
FIG. 3 is a rear, elevational view thereof;
FIG. 4 is a right side, elevational view thereof, a left side elevational view being a mirror image of the right side elevational view;
FIG. 5 is a front, elevational view thereof; and,
FIG. 6 is a bottom, plan view thereof.
Any shading and cross-hatching are not features of the design but are utilized to illustrate the surface of the snow fence design in the drawings. The frame, attachment features and support structures of the snow fence are shown in broken lines for illustrative purposes only. Any broken lines illustrative of environmental structure in the drawing are not part of the design sought to be patented. Where a broken line showing of environmental structure necessarily crosses or intrudes upon the representation of the claimed design and obscures understanding of the design, such illustration is included as a separate figure in addition to other figures which fully disclose the subject matter of the design.