More wind and some new snow will raise the danger on Friday.
We have noticed some small avalanches running further than expected recently as they gather facetted snow in the track.
Extreme winds overnight Thursday and up to 5 cm new snow on Friday will build windslabs in lee alpine and treeline terrain. These will be bigger in areas with more new snow and may run further than expected if they pick up facetted snow in steep gullied terrain.
The deep persistent problem has been less reactive in Little Yoho than in thinner areas to the east. However, weak facets still exist in thin snowpack areas (windblown ridges and cross-loaded gullies) and new snow and wind over the next couple days may make them more sensitive.
No observations from Little Yoho, but in the neighboring BYK region:
Sunshine snow safety reported a couple small windslabs in lee treeline/alpine terrain that were either skiier triggered or natural in the last 24 hours.
Otherwise, no new avalanches reported, but forecasters did not do a field trip on Thursday.
5-10cm of new snow has been blown into windslabs in the alpine and at treeline. This sits on a layer of facets and surface hoar that is likely to become a bad sliding surface in the future. Below this, the mid-pack is generally strong but a weak crust/facet layer can be found near the ground in shallow snowpack areas. At treeline, average snowpack depths are 120-150 cm. The snowpack here is generally deeper and more consolidated than areas further east in the BYK region.
A cold front is approaching from the NW. Overnight Thursday, we expect extreme westerly winds followed by up to 5 cm of snow with strong winds on Friday. On Saturday, we expect light snow with winds diminishing to moderate from the NW. Temperatures will remain cool throughout the period.
