Reading Chris Hargreaves blog, I see the team trained yesterday on the snow covered pitch, one can only assume that the snow was soft and not frozen. There was once a time when games were played on snow covered pitches, who remembers them? an orange ball was used so it could be seen better than a white one would. Has any games taken place on a snow covered pitch in recent years? or has the refs had instructions that games can not go ahead on pitches covered in snow.
Training and playing a competitive match are two entirely different entities Dave.
The critical factor is NOT snow but how it effects the free running and bounce of the ball. Such things will be entirely different on an inch or two of the stuff than on a foot or two as you can appreciate.......................I don't think football has ever been played seriously on more than an inch or two at most.
Also, the pitch markings must be clearly visible to the officials at all times and they need to be cleared and then marked in a colour that contrasts to the white of the snow. I once saw a game at Ashton Gate where the two penalty areas were cleared but then entirley covered in peat so that the pitch took on a "black and white" appearance!
Remember too that snow can and will prevent the pitch underneath freezing as long as it falls before a freeze (the normal critical temperature for snow to fall is 2 degrees celcius) but that if it falls after the freeze it will prevent it thawing until it thaws first.