Snow ratio explained: The science behind the weight and amount of snow
It's either heavy and wet or powdery soft. Well, there are actually several factors that play into how much snow will pile up and how dense it will be during any given storm.
Men shovel heavy, wet snow from the sidewalks in front of Yankee Stadium before the New York Yankees home opener on April 2, 2018, in New York. (AP Photo/Seth Wenig)
Ever wonder why some snow piles up fast or why some snow is light and fluffy and other snow is heavy and wet?
Ultimately, how quickly the snow piles up and the weight of the snow have a lot to do with the snow-to-water ratio.
The snow-to-water ratio is basically the amount of snow that is produced by 1 inch of water. A typical storm during the winter may have a snow-to-water ratio close to 10-to-1. In this case, 10 inches of snow melted down would contain about 1 inch of water, 5 inches of snow would yield half an inch of water, 2 inches of snow would produce 0.20 of an inch of water and so on.
While the 10-to-1 ratio is about average, most often the snow-to-water ratio varies greatly from one storm to another. In addition to the track of the storm, determining the snow ratio is crucial for predicting how much snow will fall.
How cold the air is through the different layers of the atmosphere determines how much snow melts on the way down.
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Also, how much moisture is available greatly determines the amount of air spaces in the snowflakes and how quickly these snowflakes will pile up on each other when reaching the ground.
Storms that occur during very cold weather in the middle of the winter and originate from western Canada, such as from an Alberta Clipper, may bring a few inches of snow from a mere few tenths of an inch of water.
A jet blows powdery snow on a runway at O'Hare International Airport on Feb. 1, 2015, in Chicago. (AP Photo/Nam Y. Huh)
Often there is little moisture available to a storm originating far from sources of water so that a mere 0.1 of an inch of water may bring 2 inches of snow. This is a 20-to-1 ratio. Snowfall of this nature can be easily swept away with a broom or blown off a vehicle with a leaf blower.
Some of the biggest snowstorms on record have a great amount of both moisture and cold air available. Storms such as a nor'easter may have a snow-to-water ratio of 15-to-1. One to 2 inches of water may bring 15 to 30 inches of snow. In this case, well-formed snowflakes in the clouds may survive the trip to the ground with minimal damage and can pile up fast.
The snow-to-water ratio approached 15-to-1 in parts of the central Appalachians during the Blizzard of '93.
Complicating matters in the spring, especially in warm, urban areas, is how much snow will melt as it falls on roads.
During the springtime, much more moisture is usually available to storms, but the temperature is higher. Large snowflakes may partially melt on the way to the ground or the snow may melt on contact with warm surfaces.
It is not uncommon for spring snowstorms to have a 5-to-1 ratio or lower. Snowfall of this nature is heavy, slushy and difficult to shovel. This type of snow tends to accumulate unevenly and clings to trees and power lines. The weight of the snow may cause trees to fall and trigger power outages.
Skiers sometimes refer to spring snow or wet snow as "mashed potato snow." Heavy, wet snow usually makes for slow skiing conditions.
In addition to temperature and moisture, strong winds may also result in a low snow ratio. During strong winds and a snowfall, the snowflakes are mangled on their way to the ground. The snow tends to become more granular in nature with only little air space left as the snow accumulates on the ground.
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