Hah, I've not (yet) seen that one! What is it? Yellow snow?

Edit: O. M. G.

http://www.telegraph.co.uk/topics/weather/4434770/Snow-Brita...

   Do you remember "the wrong kind of snow"? That was how
   British Rail tried to explain away the complete 
   disruption of their services in London and the Southeast 
   on February 7 and 8, 1991.