This has been repeated multiple times. More so in the last few years.
The setting of this dream varies, and what happens is we are outside in our neighborhood when I start to notice funnel clouds in the sky. Sometimes we have to run to get into the house (not necessarily our house, but it's usually a house), but we always have plenty of time before the tornadoes hit. In the dream I'll usually watch the sky a bit and there are multiple tornadoes coming down. I don't know if this matters, but the tornadoes usually have a cartoony quality to them, although they are 'real' and the rest of the setting, like the houses, are realistic.
Sometimes lots of people are there, sometimes it's just a few. Sometimes a tornado will hit the house, but not often. We're always safe in the end. What sticks out to me most about the dreams though is the act of watching these funnel clouds dropping out of the sky. It's fascinating.
Okay, so you don't mention what you're doing outside in the dreams before the tornadoes arrive, but maybe that doesn't matter. The key element would be that you are exposed and vulnerable, danger arises, and you seek out shelter. But from what?
The tornadoes can represent any number of things. Usually they'd symbolize whirling emotions, destructive and volatile relationships, and possibly violent outbursts. If it were only one tornado, I might think you were the one feeling so keyed up, but because there are several it's more likely you feel surrounded by people behaving emotionally and unpredictably. You seek shelter from their behavior.
Another possibility is that the tornadoes represent something different from yourself. The fact that you watch them and are fascinated by them lends itself to this interpretation. Because this thing (or things, or person, or people) is "unknown" and "foreign," you still feel the need to seek shelter . . . Because, again, you find it unpredictable and are uncertain in how to deal with it.
And then there is any combination of these interpretations (i.e., you may be fascinated by people who are reacting irrationally or emotionally to something, people having tantrums, which seems strange and foreign to you, or perhaps you are interested in someone else's volatile relationship, etc.). You're always safe in the end, though. At the core, this dream is about observing while keeping your distance.
And the fact that the tornadoes are cartoon-like only adds to the idea that, though real, they carry less weight and have less potential impact than a more realistic tornado might. Think of the Tasmanian Devil in Looney Tunes, who causes trouble but never more than Bugs and friends can deal with. These tornadoes are disruptive (as are the people or situations in your life that they represent), but they will not cause you any real grief.
Since you say this dream recurs and has become more frequent, perhaps you should review who or what has been increasingly disruptive in your life.