Not at all, they are very rare.
Or maybe I should say: they used to be? 10 years ago there was absolutely none of them, but now they do appear from time to time.
This is not true, I come from a village near Czestochowa and I remember a tornado which took place 15 years ago when I was a kid. It took off few roofs but noone was hurt as far as I remember. I heard someone saying on TV that the Polish think tornadoes is sth new in Poland because 15-20 years ago we didnt have so many TV stations that would broadcast it or people sending pictures taken with their mobile phones and so on. I think it's true. Maybe the difference is that now they happen more often...