Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
After a relatively quiet weekend weather wise, wind and snow is in the forecast for today and Tuesday. Ridgetop winds bumped up last night from the east and should increase through the day to 20-30mph with gusts in the 40s. Snowfall should be meager with only an inch or so at Summit Lake and a bit more down near Seward 6-10". Snow should fall between sea level and 300' and cover the low elevation bare ground and we'll take that!
Extra caution is advised on steep wind loaded slopes. With little soft snow on the surface currently and only an inch of new snow at best today, the winds will have a hard time creating new wind slabs. But, they often do find a way. What is more concerning however is the weak old snow at the base of the snowpack that sits under old wind loaded slopes. This is our Persistent Slab problem. Any new wind blown snow onto these older wind loaded slopes will add load and stress to the snowpack on the slope. This is also where someone could trigger a large avalanche. There is a lot of uncertainty as to how easy or not this kind of avalanche would be to trigger. But with new weather today and tomorrow it's best to avoid steep slopes being loaded by the winds.
New shallow wind slabs: If the winds verify and find some soft snow to move into drifts, watch for shallow new wind slabs to form. They could be touchy if they formed on a slick crust or surface hoar, or both.
(12/11/2024) Wind stripped ridge and loaded steep slopes at Summit Lake. This is a generally east aspect pictured from the highway. Photo: Joel Curtis
