Most tornadoes have some type of other vortices associated with them during their life cycle. They go by many different names, satellite vortex, suction spot, multi-vortex, parasite vortex and inflow vortex. All of these can be trouble makers if we aren't watching. Problem is, how do you dodge something that is already there before you see it. That is, the circulation first forms and as it tightens then it condenses. Not to mention it may rotate around the outside of the main tornado as almost tornadic speed. It's possible that a satellite vortex may be part of the main tornado circulation, that is more like a multi-vortex. This happens when we cannot identify the true outer circulation of the tornado. Many tornadoes have strong winds that extend out beyond the condensation wall of the funnel. This has been documented by chasers for quite some time. A great example was the so called Red Rock tornado of 1991. This tornado "became" a wedge when it entered a plowed field, then the width almost doubled. What actually happened was the dirt let us see the rest of the circulation outside of the condensation funnel. But the clue was there before it hit the dirt as many satellite vortices were noted rotating outside the main funnel. So getting too close may put a chaser in this outer circulation that is prone to spin-ups. Another type of satellite tornado forms in the inflow band into the tornado. I've seen this occur much more with straight inflow banding than the large arcs. Generally there is a shear interface that sets up along the pseudo warm front of the storm, in front of the FFD if you will. Low level shear will form tornadoes in these bands that usually move into and are consumed by the main tornado. For this reason it's very important for night chasers to know where the main inflow band is at all times, otherwise they may be hammered from behind. These tornadoes are mesocyclone tornadoes by the nature of where they form, but in my opinion they do not extend up very far into the storm.
A good way to see these satellite tornadoes forming is to watch the striated rain bands, and if possible stay out of them. From my own experience they often reside in striated bands. These bands are localized shear/convergence and are a good breeding ground for satellite tornadoes. For this reason many of the chaser hits from satellite tornadoes occur in rain wrapped situations as the rain is likely to mask the striated banding and their spin-ups.
Finally, at one time it was considered foolish to set up shop under a rotating wall cloud; today it's a common practice. Just remember another tornado, a second independent circulation, can easily form under a wall cloud. It's very hard to look straight up to see a vortex, or how far it is extending down as the movement vs. the low base distorts our depth perception.
