So, what was the fuel temp?
With regard to dry snow...yes, it's true that dry snow will not adhere to the aircraft wings ASSUMING the temperature of the surface of the wings is quite cold, too. But, we don't know that, and, in fact, we can probably accurately assume it is not. If the aircraft took on fuel for that flight (as it almost certainly did), the fuel temperature (fuel which probably came from underground tanks) is probably well above freezing, thereby heating the wings (and wing surface) above freezing.
Taking off, with the assumption that the snow will 'blow off', is probably not a good idea, as there will be some degree of frozen moisture adhering to the wing surfaces in the vicinity of the fuel cells. This is why most operators' SOP says, 'Make it Clean; Keep it Clean'. This eliminates any doubt.
PantLoad