Wind Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1
Winds began in earnest yesterday afternoon and continued to blow overnight, topping out at 25 gusting to 37 this morning on Hatch and 16 gusting 28 on Marmot. Although not quite as severe as some previous wind events in December, these winds have been strong enough to contribute to scouring, drifting, and the formation of shallow wind slabs 4-8" thick on cross-loaded and leeward aspects, generally south to northwest. You'll be most likely to encounter these effects at upper elevation, but I wouldn't be surprised to see a little bit of shallow drifting and wind effect at mid-elevations as well.
Be on the lookout for smooth, stiff, or hollow-sounding snow. Collapsing and shooting cracks are also indications that you're encountering unstable wind-drifted snow.
PERSISTENT SLAB
We continue to encounter structure in the snowpack that warrants mentioning the Persistent Slab problem. There are several layers of facets that have been reactive in snow pit tests, and we've received a few observations of people seeing or encountering this problem in the field, including one yesterday. Although unlikely, isolated, and stubborn to unreactive, this problem could be found in our most upper-elevation steep terrain. Fresh wind slabs today could help complicate this problem, as additional weight accumulates on the snowpack and creates a bridging effect for skiers and riders on the slope.