Very nice "T"!
As someone that goes out storm-chasing. Yes, I ride around in a van taking pictures and videos of storms that produce super cells and tornados, I do say the tube looks pretty good, however, there are some points I need to make here:
1) Tornados don't "just happen".
A tornado is spawned as part of a more intense storm systems such as a severe thunderstorms as well as hurricanes, monsoon systems, and typhoons due to the turbulence and rotation winds.
Those gigantic severe thunderstorms, known as supercells that I posted pictures of in the lightning diary, can and will spawn tornados.
Super cells are gigantic rotating thunderstorms that are many kilometers across. The big core in the middle is dumping rain with lots of wind and lightning, and these do spawn tornados. What is unique about a super cell is tornados form from the cloud down in a super cell-spawned tornado.
Landspouts and Waterspouts are still tornadic events, however, these tornados are usually weaker but can still cause damage. A land spout or waterspout will form from the ground up and is caused by twisting and rotating winds, rather than the circulation of cold air from the top of a thunderstorm. It's a bit more complex to explain than this, however, this is the difference.
A reference to the Fujita Scale might be important in the game. Seriously.
https://en.wikipedia.org/wiki/Enhanced_Fujita_scale
The Enhanced Fujita Scale rates tornado damage, after the fact mind you, based on the severity of the damage. The severity of the damage gives the estimated speed of the winds. An EF0 tornado will twist branches, throw around hay bales, maybe break things, but not kill anyone. The winds in an EF0 tornado are about 80 mph (128 Kph) while the most damaging tornados currently at EF5 are at over 230 mph (370 Kph)! These severe storms will flatten buildings, pull houses off foundations if not totally destroy them, bend up cars into crinkled bits of sheet metal, and cause absolute damage. The tornado that hit Joplin Missouri in May 2011 was an EF5 tornado. I know some people who were there during the storm, took shelter, and in the end worked a search and rescue for victims. It was a horrible mess which has scarred these people emotionally forever.
The EF scale is also used by government and insurance companies to determine disaster relief funding and benefits. This is where this could come into play in the game. A city hit by a big EF4 or EF5 tornado would suffer severe damage. The cost to rebuild would be well beyond what a cities budget could afford. With the EF rating high like this, the city could receive either or low interest loans or even grants to rebuild the city. There could be a limit as to how many times the city receives recovery money though.
Now there is something to keep in mind. A tornado that occurs in the middle of nowhere and causes no damage is rated an EF0. Remember even if the tornado was big and huge, and very dangerous, because no one is hurt, or anything destroyed, the storm is an EF0 because the EF-scale rates damage after the fact.
Taking shelter...
Most people will receive weather reports days ahead of an impending severe weather pattern. Our NOAA, National Weather Service produces maps and weather forecasts via the Storm Prediction Center which is located in Norman Oklahoma. This group builds computer prediction models based on data gathered every 6 hours and sometimes more using weather balloons, satellites, and ground observations. Their predictions are quite accurate, however, tornados still are difficult to predict exactly where they will form. On severe weather days, during the spring and early summer months in the Great Plains, trained weather observers - actually volunteers and storm chasers, will search and watch the skies for probable severe weather.
Storms will occur towards the evening, but this is not always the case. People will be observing the skies for hours at a time, observing severe thunderstorms which exhibit the possibility of producing tornados, usually supercell thunderstorms, and when there is a funnel cloud, it is watched until it forms a tornado. A funnel doesn't count and it becomes a tornado only when it touches the ground. At this point, the tornado is reported and is tracked, and warnings are sent out to nearby cities and towns where sirens will sound and people are supposed to take shelter.
In areas prone to tornados, the residents will take shelter in their storm shelters if they have one. In general they don't have them at the size as they are in the game, they're more like small bunkers in the ground near the houses. If people are in public buildings, they will take shelter in basements, back corners of buildings, and even in freezers of supermarkets. In general it's in the lowest level in the smallest room in the interior of buildings away from windows. The reason for taking shelter anywhere is due to the quick movement of these storms. They can move about 60-70 mph in the early spring (96 kph - 112 kph ) to half that in the latter part of the summer months. With quick moving storms, people need to take shelter anywhere as there is no time to bunker down for a tornado. The bunker, as depicted here, is good for other disasters, but never a tornado as people would never have time to get to a shelter in time.
This helps explain stuff about safety.
http://www.spc.noaa.gov/faq/tornado/#Safety
There's a lot to this, and this add-on looks amazing.