Snow Bonding
Avalanche forecasters evaluate how well the layers in a snowpack are bonded together at their interfaces by conducting strength and stability tests in the field.
Weather forecasters can gain insight into how well new snow will bond to the existing snow surface by evaluating weather conditions immediately prior to the arrival of the next storm.
Good bonding is likely if:
- The snow surface is relatively warm (air temperatures near or above freezing) just before new snow falls; then new snow of almost any temperature or crystal type will bond with it
- There’s a crust on the surface and new snow occurs at relatively warm temperatures
- Weak snow and warmer temperatures precede a warmer snowfall or rain event
Poor bonding is likely if:
- The new snow surface is relatively cold and consists of a weak snow type
- The new snow surface consists of preserved, colder snow crystals, such as stellars and dendrites
- The new snow surface is a crust and air temperatures remain cold as new snow begins falling
Key points:
- Good bonding creates a strong layer of snow, and good bonding between all layers makes a stable snowpack
- Poor bonding means that a weak layer of snow exists, and poor bonding between layers makes an unstable snowpack
- Warmer temperatures promote bonding