The danger rating reflects the highest expected for the day, driven by solar input and freezing levels rising to 2500m in the afternoon. Start and finish early.
The lower snowpack remains weak compared to deeper western areas such as Little Yoho.
An 80 cm thick midpack slab sits over a weak, facetted base. On most slopes, recent sun crusts and the buried March 27 rain crust cap the slab, adding some strength. Be cautious in thin alpine areas or where these crusts are weak or breaking down in the heat. Likelihood may increase with heating.
We expect this problem to become active as the sun takes its toll on solar aspects. The best way to minimize risk is to start and end trips early, before things heat up.
A few natural, persistent slab avalanches to size 2.5 occurred on Pilot Mountain on Thursday (trigger unknown). These were on high, North-facing terrain, showing that avalanches are still possible on the deeper layers. No other avalanches were reported on Thursday.
Surface crusts exist on solar aspects to ridgetop and on all aspects at treeline and below. On northerly aspects, 10-30 cm dry snow with isolated wind slabs in lee areas of the alpine. The March 27 crust is 30-70 cm deep and extends to about 2500m. Below the settled midpack, there are still facets and depth hoar to the ground.
Expect 2500m+ freezing levels on Friday with plenty of sun and light winds. See image below for more details.
