oh man. this is just like the UK movie "Flood". In the movie, a huge tidal wave flood the city of London and the eastern coast. The wave breach the flood gate protecting the city of London
Now, if it ever snowed in London for a few days and London got 3-4 inches of snow, then there really would be a National Emergency. The south of England would literally grind to a halt.
A business client from London had travelled up from London to Dundee in Scotland in March 2006 for a business meeting. There was a snow blizzard outside and there was a look of panic on his face. It didn't help when I mentioned the film 'The Day after Tomorrow' and told him about an RAF Mountain Rescue Sea King helicopter, which had been forced down over the Cairngorms because of the extreme weather conditions a few days before, just like in the film.
http://news.bbc.co.uk/1/hi/scotland/4768116.stm