There has already been F1 tornados in Sydney.
I remember driving home on the M4 back in 2000 & seeing the path it cut through Greystanes. Trees just snapped in two on both sides of the M4 for about 50meters & roofing material all over the road. Then the next day I drove down an adjacent road a few hundred meters away & you could clearly see the path it cut. Trees & scrubs, some tree trunks a few feet wide, just snapped like twigs.
http://www.bom.gov.au/nsw/sevwx/tornadofact.shtml