DENVER (KDVR) — Spring snow is notorious for causing downed power lines and broken tree branches in Colorado.
This in part is because leaves are starting to grow on trees, creating more surface area for snow to stick to and weigh down the branches. But another big factor that determines the weight of snow is the temperature.
In the middle of winter, when temperatures are colder, liquid-to-snow ratios are usually around 15:1 or 20:1. This means that if 20 inches of snow fell and was reduced to liquid water, it would add up to an inch of water. This is what we describe as light, fluffy snowfall that isn’t good for making snowballs or snowmen.
When temperatures are closer to freezing, commonly seen in spring snow-to-liquid ratios go down to 10 to 1 or even 5 to 1 if temperatures are warm enough. This is what creates heavy, wet and slushy snow that can cause problems for powerlines, trees and even roofs.
In the spring, when snow ratios are closer to 10 to 1, it means that 10 inches of snow would be 1 inch in liquid water form.
The graphic below shows how heavy snow is on a roof depending on the snow-to-liquid ratio. At a 15-to-1 ratio, the snow is light and fluffy. If 24 inches of snow falls over 1,500 square feet at this ratio, it is like having the weight of two trucks on your roof.
At a 5-to-1 ratio, the heavy and wet snow will add up to a lot more weight than a 15-to-1 ratio. If 24 inches of snow falls on 1,500 square feet at a 5-to-1 ratio, it is close to the weight of having 6 trucks on your roof. This is why spring snow brings a lot bigger impact to trees, power lines, and roofs.