Snow-to-liquid ratio is a key factor in forecasting snow

One of the tools meteorologists use to determine how fluffy or wet snow is, is a snow-to-liquid ratio. That means how many inches of snow does it take to get 1 inch of liquid — i.e., if it were all rain? 
A storm featuring a higher snow-to-liquid ratio will result in light, fluffy snow. This could be a storm producing a ratio of 20 to 1. This means one inch of rain would produce 20 inches of snow. This tends to happen with an extremely cold storm as the cold air can hold less moisture.
Another way to think about this is to consider the texture of snow. A cold storm leads to light and airy snowflakes. This allows the snow to quickly stack up as no weight is compressing prior accumulations. 
 A storm featuring a lower snow-to-liquid ratio will result in heavy, wet snow. The type that breaks your back as you dig out. This could be a storm producing a ratio of 5 to 1. This means 1 inch of rain would produce 5 inches of snow. This tends to happen with a warm storm; temperatures will often be hovering around freezing. This is what we typically see with springtime snowstorms. 
The average snow ratio is about 10 to 1.