Wind Tunnels - Tornado winds roar through a school from windward to leeward side. Therefore, students should sit or lie flat with heads protected, corridors that open to the south and west should be avoided, if possible, as many doors as possible should be closed into corridors that are used for sheltering, and students should not be sheltered too near any door or entrances into a corridor. Windward Walls - It is impossible to guarantee tornado direction. We must plan on preparing for the most violent kind of tornado, which almost always approach from the west, southwest, or south. South and west walls on the outer edge of the building are very dangerous.
Exceptions do occur where east-facing walls also are blown inward.
North walls rarely ever are blown inward. Tornado winds increase with height. This means that walls on upper floors in a building will receive greater forces from the wind than will the first floor walls. Windward wall collapse is therefore even more common on upper stories. If the wall collapses, then naturally the ceiling will collapse too.