Correct me if I'm wrong, but it's not customary for aircraft to land or takeoff if it involves leapfrogging over snowploughs on the runway.
Ergo it follows that if the runways (and exits, and taxiways, and stands) have to be cleared of snow (and it was snowing pretty well continuously yesterday) then capacity will be reduced while snow clearance is taking place, plus of course the effect that poor visibility has on the movement rate even after the runways have been periodically cleared.
I can't think of any airport that encounters snow to which the above doesn't also apply to a greater or lesser degree. To expect continuously falling snow not to affect an airport's operations is completely unrealistic.