Cornice failure, loose wet avalanches and even slab avalanches are possible as the upper snowpack feels the strong sun and warming temps for the first time today. Really watch your exposure to overhead hazard, it would be easy to be surprised by weird avalanches today.
A thick rain crust can be found 30 to 60 cm below the surface. As temperatures begin to warm Thursday and slopes are subject to the strong sun, the overlying slab could start to wake up. Strong sun and warming temperatures are also likely to warm cornices which could trigger avalanches when they fail. This is one to keep our eyes on Thursday and Friday.
Sunday/Monday's storm snow has settled into a 20 cm slab. It seems to be most problematic in wind exposed features near ridge crest. These slabs may become more sensitive to both natural and human triggering Thursday as the warming temperatures and strong sun heat up the upper snowpack. Watch for loose wet avalanches on solar aspects too.
Sunday's storm produced 15 to 25 cm of storm snow that has settled to about 20 cm. This snow rests on a variety of old surfaces including a firm crust on solar aspects, soft faceted snow, possibly a spotty surface hoar layer and old wind slabs near ridge crest. The new snow has been formed into variable wind slabs in exposed terrain features, especially those near ridge crest.
A thick rain crust that has facets associated with it sits 30-60 cm below the surface and can be found up to ridge top. The avalanche listed above is the first activity that we've seen on the crust since February 17.
The mid-pack is well settled and strong, but the base of the snowpack contains basal facets that are most prominent in shallow rocky start zones.
Clear skies and warm sun for the next couple of days...
WEDNESDAY NIGHT: Freezing level at valley bottom, light southwest wind at lower elevations, moderate to strong west/northwest wind at ridge top, no precipitation expected.
THURSDAY: A few clouds, freezing level starting at valley bottom rising to about 1700 m, light to moderate southwest wind at lower elevations, strong west wind at ridge top, no precipitation expected.
FRIDAY: Clear skies, freezing level starting near valley bottom rising to about 2200 m, light to moderate west/southwest wind, no precipitation expected. Freezing level holding around 1800 m Friday night.
SATURDAY: Broken cloud cover, freezing level lowering from 1800 m to 1500 m, light to moderate southwest wind, 3 to 6 cm of snow expected.
Natural and human triggered wind and storm slabs to size 1.5 were observed Tuesday on north/northeast facing features above 1900 m. The human triggered wind slab avalanche is thought to have ran on the early February crust/facet combo. This MIN observation from Harvey Pass shows a skier triggered avalanche that looks like it could have run on surface hoar.
Widespread natural and intentionally human triggered avalanche activity to size 2 was reported from all aspects Monday. One of the wind slabs was up to 45 cm deep in places. The bulk of the activity was above 1750 m which suggests that wind loaded features near ridge line appear to be the problematic features.
