Snowfall total forecasts were increased Sunday morning for a winter storm that is now expected to bring up to 5 inches of snow to northwestern New Jersey through Monday morning. The National Weather Service has issued a winter weather advisory for Sussex and western Passaic Counties, where the heaviest snow is expected to fall, through 7 a.m. Monday. “Plan on slippery road conditions, especially untreated bridges and overpasses,” the weather service said in an update Sunday morning ahead of the storm. N.J. weather: How much snow will you get? Latest snowfall forecast map for your town.Areas no…