Scientists are using lasers, satellites and even sound to determine what is falling from the sky—but the best tool may still be the human eye.

A storm system is poised to bring a fresh coat of accumulating snow to Lancaster County − possibly the heaviest snowfall the county has seen in years.

A storm covering half of the U.S. is likely to bring more than a foot of snow to much of Pennsylvania, forecasters now say. “There is increasing confidence,” the National Weather Service says, “in widespread snowfall amounts over 10″ across central PA.

AccuWeather is predicting around 6 inches of snow for Sunday in York County and also predicting snow for Monday, but has no precipitation amount for that day. Weather Underground says the impact will be substantial Sunday with 10 inches falling on York County. That comes after the 5 inches they expect to fall on Saturday.