This weather 101 segment is going to focus on the formation of tornadoes. While we very rarely see tornadoes here, it is still interesting to talk about the actual physics that take place and allow tornado-producing thunderstorms to form.
There are a few key ingredients to tornado formation:
- Instability (energy)
- Wind shear
The lift can be caused by a few different mechanisms, though we most commonly see stronger thunderstorms along strong cold fronts or very close to a low pressure system.
Moisture is generally available through the spring and summer months as we move in more humidity. While this can be a limiting factor for us, we usually have enough moisture to fire some thunderstorms with our frontal passages in the warm months.
Instability can be a limiting factor for stronger storms for us. Still, we definitely have out fair share of days with energy to use. This is a result of heat and moisture content. There are certain patterns that lend themselves to more or less energy. In the case of tornadoes, we need at least a little bit of instability to get those stronger thunderstorms to fire up.
Wind shear tends to be a limiting factor for us as well. This is when the wind’s speed and direction changes as you get higher in the atmosphere. Due to our terrain, we sometimes cannot get much of a directional change in our wind. However, we do get enough sometimes to result in some stronger storms. This wind shear helps to organize the thunderstorm and allow it to become stronger. It also plays a role in the formation of the tornado itself.
The different wind directions cause the air to begin to roll horizontally. Eventually, this rotation becomes well-established.
Sometimes, the strong lift associated with the thunderstorm can move this rotation so it becomes vertically oriented. The result is a tornado.
Again, tornadoes do not happen too often here, but they do on occasion. Always know where your safe space is in case you ever end up under a tornado warning. Have a plan in place!