The science behind melting snow
When hearing about snow entering a region, many people's immediate thoughts turn to the question, "How much?" As a meteorologist, there are countless things to think about when forecasting snowfall. One of the less thought of principals falls under the category of melting snow. It might seem counterintuitive to worry about melting snow before snowfall even occurs, but it is very useful.
An important factor in determining snowfall accumulation is to look at previous air and surface temperatures up to 48 hours prior to the actual event. If multiple warm days are experienced then ground temperatures will remain well above freezing causing any falling snow to melt quickly upon contact.
If snow is already on the ground prior to the incoming system, then albedo is explored. Albedo is the measure of reflectivity by a surface or color. Newer accumulated snowfall has a high albedo meaning the suns light and energy is reflected at higher percentages allowing for less absorption. Snowfall that sits on the ground for multiple days is more likely to melt at quicker rates because the albedo is lower causing the snow to absorb more light and heat.
A final key component to accumulating snowfall and melting rates lives in snowfall rates. Even if the surface temperature is above freezing and snowfall melts upon contact, increased snowfall rates can topple onto itself creating a slush. Continuous, heavy snowfall rates will then fall on this slush which has a lower temperature allowing for accumulation to occur. This can happen on roadways creating dangerous conditions.