Tornadoes have extremely low atmospheric pressure. If a house is sealed tight, the higher pressure inside will push outwards, causing the structure to explode.
Wind. When a tornado strikes, the extreme wind speed creates a massive amount of lift and shear . If wind penetrates the house—through a broken window or an open door—it acts like a balloon inflating inside the structure. This internal pressure pushes outward on the walls and upward on the roof. Combined with the suction of the wind passing over the roof (the Bernoulli effect), this creates a recipe for structural failure. The goal is to keep the wind out , not let it in . should you close interior doors during a tornado
Decades of post-tornado engineering studies (including from NIST and the Red Cross) have debunked the idea that opening windows or doors equalizes pressure or prevents a house from exploding. Modern houses are not airtight enough for pressure to build explosively. Opening an exterior door during a tornado actually invites wind and debris inside, increasing damage and risk of injury. Tornadoes have extremely low atmospheric pressure