Was That a Tornado Outside Twin Falls? Nope
Twin Falls, Idaho (KMVT-TV / KSVT-TV) Tuesday's cold air funnels that formed overSouthern Idaho are different than the funnels and tornadoes you think of that are typically associated with severe storms. While Idaho is not immune from tornadoes, the weather conditions and environment that formed Tuesday's funnel clouds are very different than the conditions that form the strong destructive tornadoes most people associated with funnel clouds. Check out Brian Neudorff's graphics that explain it all.
First you need to understand the difference between a funnel cloud and a tornado. A funnel cloud is rotation coming down out of a cloud but NEVER reaches the surface. Once a funnel cloud or the rotation reaches the ground, then it is classified as a tornado.
The cold air funnels we saw Tuesday are typically associated with cold upper low pressure systems. These funnels are usually weak and rarely touch the ground. When they do touch down, the resulting tornadoes are small and relatively weak causing little damage.
On the other hand, the funnel clouds that produce the tornadoes most people are familiar with come from severe thunderstorms. Many of these severe thunderstorms are supercell storms that are rotating and spinning themselves. Unlike cold air funnels that form in a relatively cool and cold atmosphere, tornadoes associated with severe storms form in a very warm moisture rich atmosphere that helps give the storm its strength and fuel.
Idaho can and has seen strong damaging tornadoes before. The state averages somewhere around 6 tornadoes a year. Most occur in the eastern part of the state but we can see tornadoes here in the Magic Valley and the Wood River Valley. Most tornadoes that form in Southern Idaho are between an EF-0 and an EF-1. There have been a few EF-2, but they don't happen very often.