Weather Forecast
Tuesday: An approaching Pacific frontal system from the North may bring cloudy skies with light snow amounts through the day. Ridgetop winds from the South @45km/hr. Treeline temperatures near -9. Wednesday brings mainly unsettled conditions with lsnow amounts near 10cm. Ridgetop winds moderate from the SW. Thursday: Cloudy, few flurries. Treeline temperatures near -8. Ridgetop winds light-moderate from the NW.
Avalanche Summary
Fairly widespread natural cycle up to size 2.5 occurred through the weekend. Most elevations and aspects seemed to be ripe. Several heli remotes occurred during an operational bombing mission yesterday, up to size 2. These were on NE-SW-W aspects above 2200m. Crown depths 10-25cm, within the recent storm snow. Skier triggered avalanches up to size 2 have also been reported on northerly aspects. I suspect the natural activity will start to taper off, with the exemption of possible solar effect on southerly aspects. I do think avalanche conditions will remain touchy, and susceptible to rider triggers through the forecast period.
Snowpack Summary
The recent total settled storm snow is near 60cm. This storm was initially accompanied by moderate to locally strong south and west winds, creating intense slab production on North through East facing terrain at treeline and in the alpine. Wind slab releases on north facing terrain have been as deep as 100cm. At the end of the storm winds turned northerly, and intense reverse loading occurred on southerly aspects. Reports indicate the new wind slabs are not bonding well to the southerly scoured, sun crust surfaces. All this new snow sits on a variety of old surfaces. These include melt-freeze crusts at lower elevations and spotty areas of surface hoar in sheltered areas. Steep south aspects in the alpine also host a buried sun crust. Easy shears persist in the new storm snow (decomposing fragments down 25cm) and at the deeper interface (down 60cm). Below this, the mid and lower snowpack is well bonded and strong.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.