whisting

"Whisting" (verb) is what happens when wind sweeps rain off a roof or other flat surface with the force of the wind. Elements of "whistling," "winding," "whiffing," all come to mind. We've all seen the effect when we see rain move off ("whisted off") rooftops, buildings, car hoods - that sheeting action brought by rain and wind, freshly whisting off into chaos.

We watched the storm in the late afternoon, the wind whisting the driving rain off the nearby rooftops in transparent sheets, like the veils of some ghostly bride.