Europe can produce some very powerful tornadoes and supercells. In the UK alone we get more tornadoes per unit area than anywhere else although these tend to be weaker than the ones in the states with powerful tornadoes being few and far between. The last big one was in London a few years back.
Mainland Europe itself gets alot of vortex phenomena, tornadoes, waterspouts, funnel clouds etc and big hail events. Keep an eye on the ESTOFEX forecast for these major events in the future as they predicted the Poland outbreak very accurately.
Here's some basic info from wikipedia but a deep search will be needed on the net...
http://en.wikipedia.org/wiki/List_of_European_tornadoes_and_tornado_outbreaksSome history from TORRO
http://www.torro.org.uk/TORRO/research/whirlextreme.php
