Watch for wind slabs that can be found in the alpine and steep, isolated locations at treeline.
Extreme W to SW winds on Thursday night and up to 20cm of recent snow have developed slabs in lee alpine and isolated 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 snowpack is generally deeper and, thus, stronger in this Little Yoho subregion than in most of the BYK forecast region. However, thin snowpack areas, such as windward and exposed terrain, may have weak basal facets at the base of the snowpack, as is commonly found further east.
On Sunday, a field team in the Emerald slide path area was able to kick off very small wind slabs at treeline in extreme terrain and noted a natural size 2-2.5 wind slab on the SE face of Carnarvon (above Hamilton Lake). This had slid in the past 24 ish hours and appeared to have started as a cornice failure.
10-20 cm of new snow since Dec 7 has been blown into slabs in the alpine and isolated treeline locations. The recent snow sits on a layer of facets and surface hoar in some locations. Moist snow up to 2400m on steep solar aspects.
The mid-pack is generally strong; however, a weak facet layer can be found near the ground in shallow snowpack areas.
At treeline, average snowpack depth ranges from 120 to 150 cm and overall is deeper and stronger than it is East of the divide.
Monday brings moderate NW alpine winds, temps from -4 to -9C at treeline and no new snow.
