Soft snow describes conditions that are yielding and forgiving, contrasting with hard-packed or icy surfaces. Snow is a dynamic substance classified primarily by its density and its moisture content. The constant transformation of the snowpack, driven by temperature, wind, and mechanical forces, necessitates a specific vocabulary to accurately describe surface conditions. This classification system is important for meteorological reporting and for people engaging in winter activities, as different soft snow types affect safety, effort, and enjoyment.
The Ideal: Understanding Powder Snow
The most celebrated type of soft snow is “powder,” defined by its extremely low density and unconsolidated structure. True powder forms when snowfall occurs in very cold temperatures, typically well below the freezing point, which limits the moisture present in the snow crystals. This lack of moisture prevents the individual ice crystals from bonding tightly, resulting in a fluffy texture that contains a high percentage of trapped air.
For snow to be considered high-quality, low-density powder, its water content is often in the range of 4 to 7 percent. This low density allows skiers and snowboarders to experience a sensation of “floating” on the surface, which is a signature characteristic of a perfect powder day. However, for optimal flotation, some experts consider a slightly higher density of around 8 percent water content to be better, as the lightest snow, sometimes as low as 5 percent, can cause equipment to sink rather than plane across the top.
Subcategories of this ideal soft snow exist to describe regional variations or extremes in dryness. “Champagne Powder” refers to extremely light, dry snow that often yields ratios of up to 30 inches of snow for every one inch of water. Another descriptive term is “blower powder,” which is snow so light and dry that it easily billows up and sprays into the air when disturbed, often leaving a trail of “cold smoke.” The formation of this extremely light snow is linked to frigid temperatures, often below \(-10\) degrees Celsius, which prevent water from binding the crystals together.
Consolidated and Settled Soft Snow
Soft snow conditions can persist and change after the fresh snowfall has ended, particularly through mechanical action or natural settling. “Packed Powder” is a widely reported condition that begins as fresh powder but has been compressed either by grooming machines or by a high volume of traffic. This compression increases the snow’s density and creates a more stable, consistent surface compared to fresh powder.
The snow still retains a soft, forgiving quality, allowing for easy edge grip and confident turns on groomed trails. Unlike hardpack or ice, packed powder has not undergone a melt-freeze cycle, meaning the individual crystals remain cold and dry, simply pushed closer together. When powder settles naturally over a few days without being groomed, it becomes “Settled Powder,” which is slightly denser than fresh powder but still soft and untracked off-piste. This natural process of settling is where the snow crystals bond slightly under their own weight, increasing the overall density of the snowpack.
Soft Snow Terms Related to Warming and Melting
Soft snow can result from a warming trend or fluctuating temperatures, leading to conditions with a higher moisture content. “Corn Snow” is a soft condition that typically appears in the late winter or spring, forming through repeated melt-freeze cycles. During the day, the surface melts, and the liquid water works its way into the snowpack, only to refreeze at night. This process creates large, rounded, granular crystals that resemble kernels of corn, which is how the snow gets its name.
When conditions are right, corn snow provides a surface that is soft and smooth, allowing for predictable turning, often described as “hero snow.” If the temperatures continue to rise past the ideal window for corn, the snow can become fully saturated with water and begin to break down into a heavy, slushy consistency. This saturated soft snow is commonly referred to as “Mashed Potatoes,” which can contain 20 percent or more water content. Moving through mashed potatoes requires significant effort because the high water content causes a heavy, sticky resistance that can make turning difficult and unpredictable.