It's
b - equipment (and staff)availability
a - initial snow depths
c - on the ground management
b-If you haven't got the equipment, then 1cm can close you down for a long time. If your staff can't get to work because of the snow ...
a-
Type of snow is a significant factor as is the state of the ground it falls on, and previous/prevailing/future weather
c-If you haven't got 'b' nailed down at the start of the exercise you're not going to be able to manage it very well, regardless of how dedicated/keen your snow team is.
Mr BAA spokesman said their teams had been going '24hrs without sleep'
. Let's hope that's not literally the case, otherwise cue an CAA/H&S investigation on his doorstep anytime now ...