Storm Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
There is a lot of variation in the snow quality/ condition with changes in elevation, aspect, and forecast zone. There is also variability in the #1 avalanche problem that a user could encounter with wind slab and storm slab being at the top of the list, but neither one screaming for the #1 slot and depends on location.
Starting with storm slab, this problem is the most likely to be encountered if you are traveling in the Maritime zone. 8 inches of new snow have been recorded at the Sugarloaf snotel, with another trace expected in the early afternoon. Since this snow has fallen within the last 36 hours, bonding with the old snow surfaces may not be complete. This can create instabilities at the new and old snow interfaces. Winds have ticked up slightly out of the south, which creates deeper pockets of new snow that will be more sensitive than areas unaffected by wind. New snow is accumulating on buried surface hoar that has been observed in specific locations up to 3800'. Buried surface hoar has the potential to act as a weak layer in our snowpack in specific locations once it is sufficiently buried. At this point, observations have shown this weak snow to exist on the north side of Thompson Pass and has not yet been found in the Maritime zone.
As you move North from the Maritime zone new snowfall amounts quickly decrease to 2-4 inches on Thompson Pass and only a trace at 46 mile. These lower snowfall amounts shift the focus from storm slabs to old wind slabs on Thompson Pass and North. The last week of weather has been typified by light rounds of snowfall and periods of clearing with light to moderate winds blowing from mutiple directions. Shallow instabilities created by wind loaded snow have been observed lately in isolated areas. These have been found to be less than 6 inches deep and still show some reactivity. Adjust your assessment to what avalanche problem exists in the area you choose to travel. Where more than 8 inches of new snow exists, pay attention to how well it is bonded to old snow surfaces by using hand shear tests and small inconsequential test slopes . Where new snow is shallower, look for visual clues of wind redistribution and target test slopes that look likely to accumulate wind slab.