Wind Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
Storm snow and wind from last week formed wind slabs that continue to linger in alpine terrain.
Cornices remain fragile, limit exposure. Strong solar input can rapidly affect the snowpack despite cool air temperatures, so plan to start early and finish early.
Storm snow and wind from last week formed wind slabs that continue to linger in alpine terrain.
A facet/crust interface from Jan is buried 70–180 cm deep. We are still seeing some hard, sudden test results at elevations above the Mar 20th rain crust (~2300 m). Large triggers like cornice falls or surface avalanches may trigger this layer, similar to the Wapta Peak avalanche observed today.
Forecasters on Mt. Field today noted that cornices are particularly fragile. They observed a size 3 cornice-triggered avalanche, approximately 48 hours old, that released from Wapta Mountain and ran to the moraine on Mt. Field. Lake Louise patrol also reported that small cornice failures were triggering small wind slabs in alpine lee terrain.
20-45 cm of snow fell over the last week, with moderate to strong SW winds creating wind effect in open areas. Wind slabs linger. This snow fell on the Mar 20th rain crust, which exists below 2100-2300m. Above this crust on solar aspects, various buried sun crusts exist, some extending to higher elevations. Cornice growth continues.
The Jan 24th facet layer is buried 70–180 cm deep at treeline and in the alpine, with some tests still producing hard, sudden results
Slightly warmer temperatures on Wednesday, with valley highs around 2 and ridgetop temperatures near −6. Up to 8 cm of snow is expected late in the day, though model guidance remains uncertain. Winds may increase into the low end of strong from the south by midday.