I doubt it will snow tommorow night because the Irish Sea is too warm for it. The sea is acting as a huge pool of milder air over it. Plus the winds are coming in directly from the milder sea if the frontal system approaches. Honestly I would probably expect some freezing rain for the hour or two, if lucky bit of sleet for half an hour. The puddles probably turn to ice overnight. That is mine expectation. Im looking forward to the freezing rain that sticks to the ground and everything frozen over which is quite cool. Temperatures on Monday probably reach to 4 - 5C at best with some showers, wintry over high ground. So the cold air mass may return by then.