No, it's not a crime, it's just not something a productive adult should be doing with their time. And those in the crossfire may not be overjoyed at a pelting of snow.

[Case in point. He comes to a halt, most of the snow removed but an unpleasant wet patch irritating his skin. He really hates when people ruin his clothes, he can just always feel it.] Perhaps you should move along off the busy street and not disturb those who don't wish to be hit?