Why is it no longer recommended to open a window when a tornado is imminent?
While it is true that pressure on the roof can be relieved by opening a window on the leeward* side of the house, the direction of an attacking wind will be unknown. Even when the tornado approach direction is known the winds of the tornado are spinning; so depending on which part of the tornado passes over the house, the winds on the wall could be from any direction. Opening a window on the “wrong” side could be detrimental to the building and waste valuable time needed to reach a place of safety. Additionally, most residences and commercial buildings have enough natural venting to relieve any change in atmospheric pressure which may occur. (One square foot of opening per 1000 cubic feet of volume will “vent” the atmospheric pressure change effects of a severe tornado.) Finally, it is noted that severe winds act on a building before the largest portion of the atmospheric pressure change can become effective; hence, window failures or failures of other components are likely to “open” t
