New wind slab development will keep the avalanche danger elevated at upper elevations.
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 15 cm of new snow has built 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:
Local ski hills were reporting small reactive winds slabs specific to immediate lee features at alpine and tree line elevations.
10-15cm 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.
Northerly flow over the weekend will bring moderate to strong north winds (reverse loading) to the region. Cloud cover will persist through Saturday, with a clearing trend starting Sunday. Only a trace of snow accumulation is expected. Alpine temperatures will hover around -10°C, while valley bottoms will remain below freezing.
