1. You should open the windows before a tornado to balance the pressure inside your home.
In the event that your home is under a tornado threat do not waste valuable time opening windows, instead, get to your tornado safe spot as soon as possible! The assumption here is that due to pressure changes that occur with tornadoes, opening a home’s windows will balance the pressure and save the structure. Nothing could be further from the truth.
Most structural failures are caused by the loss of the structure’s support system, which in most cases is the roof. This happens when winds push their way into a structure and become “trapped” with no way out and more incoming winds preventing the wind inside the structure from escaping.
When this happens, the air is forced up and thus the roof is removed. As soon as the roof is removed the structure losses its support system and walls can collapse. This is why the safest place in your home is an interior room with no windows. Do not waste precious time opening windows during tornadoes, chances are the debris from the tornado will do that for you anyway and you don’t want to be in the path of flying glass!
2. Overpasses are safe tornado shelters.
This is one of the most dangerous misconceptions about tornadoes. During the F5 tornado that struck the Oklahoma City Metro on May 3rd, 1999, there were multiple fatalities resulting from people seeking shelter under highway overpasses. An overpass creates a tunneling effect that increases wind speeds as the winds compress to travel beneath the overpass.
Any person who is caught in these winds will likely not survive as the winds will also carry very fast debris as well. On top of this, parking beneath overpasses during severe weather is ill-advised and can create a traffic jam that prevents emergency services from being able to do their jobs. If you are caught outside and absolutely cannot escape an approaching tornado, the safest thing to do is quickly locate the lowest area around you (such as a ditch) and lie as flat as possible while covering your head with your hands. If you’re in a vehicle, be sure to pull completely off the road before exiting.
Laying flat in a ditch may sound scary, but the idea is to keep the winds above you, not under you. Tornadoes don’t really “suck”, they instead “lift”, and in order to lift, the winds have to get beneath your body. Sheltering in an overpass puts you directly into the strongest winds. Don’t do it!