As we move into summer across Manitoba, thunderstorms and, in particular, severe thunderstorms have begun to rear their ugly heads. This week we’ll look at tornadoes, but instead of me rambling on and giving you a technical breakdown of tornadoes — how they form, what to look for, safety, et cetera — I am going to use a series of amazing pictures that were sent to me several years ago. But first, I need to touch on a couple of weather topics that have impacted our region over the last little while.
First off, what’s been up with the winds? I have had a lot of questions about this. After poking around I found a news story that indicated that this has been the windiest late May and early June in 30 years. I then dug into my own wind data and saw a very similar result. I know I am tired of my weather computer telling me, “It’s kite-flying weather,” nearly every day. Good news is that it looks like our overall pattern will be changing to a less windy one.
The second topic was the incredible overnight warmth that occurred on June 16-17. I don’t remember the last time overnight temperatures hovered between 25 and 27 C from 9 p.m. to 5 a.m.; you just don’t see that happen. Trouble with this unique event is that it won’t show up in the daily data as the low temperature on any given day can occur at any time during that day. On June 16 we saw a cool start to the day and on June 17 we saw temperatures briefly drop into the low 20s between 5 a.m. and 7 a.m. Now, back to tornadoes!
In Photo 1 we see a classic textbook example of an approaching thunderstorm. This is a supercell thunderstorm. You can see the central area of convection with the nice smooth band of clouds in the middle of the picture. The low clouds pushing out in front of the storm are a result of the outflow of air from the storm. This outflow of air helps to lift the warm air surrounding the storm as it is being pulled in. You couldn’t help being nervous seeing this storm coming.
In Photo 2 we see another perfect textbook example, but this time it is of a wall cloud. You can easily see how it gets its name. A large portion of the thunderstorm has lowered significantly compared to the rest of the storm. The little tails of clouds on each side of the wall cloud are again showing the rapid inflow of air into the storm. This whole cloud formation will often be rotating, and it is from this feature that you expect to see a tornado form.
Photo 3: Tornado! While the tornado in this picture has yet to become fully visible from the parent cloud to the ground, you can already see the effects of the tornado on the ground. You can see the swirling taking place at ground level, indicating the funnel cloud has now extended to the ground and become a tornado. As with a large majority of tornadoes, they often form outside of the main rain area of the thunderstorm.
In Photo 4, we see a beautiful example of a green thunderstorm. While seeing the other images in Manitoba is pretty rare, this type of thunderstorm is a little more common in our area. Personally, I have yet to read of any definitive reason for the green colour. Research has shown it is not simply the reflection of green vegetation but is more likely the effect of sunlight being scattered and refracted by large amounts of water and ice within the storm. With green thunderstorms, one thing is almost always a sure bet: you’re going to get torrential rains and/or severe hail. So, if you see a green storm coming — take cover!