Interactive Snow Water Equivalent (SWE) and Snow Depth
Unlike snow depth, which can blank out during heavy snowfall events and settles between storms, SWE is a more stable metric of how much snow accumulated during a storm. It represents the amount of liquid water contained (or added) to the snowpack in inches, which translates directly into load applied to the snowpack.
A good rule of thumb for estimating new snowfall from SWE accumulation at Montana SNOTEL sites is to assume a ratio of 10:1. That means if 1.0" of SWE is added to the snowpack, 10 inches of snow may have accumulated. "Cold Smoke," which is very low-density new snow (95% air, 5% water), equates to a 20:1 ratio. During the fall and spring months, when temperatures are typically warmer during storms, you might consider using a lower ratio of 8:1 or lower.
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