Forecasters feel that we will be near the upper limit of moderate in the alpine for Friday. Use small terrain to test the snow and get an idea of how the bigger features will behave.
Weather Forecast
Freezing levels will drop to 1900m tonight with winds continuing to blow out of the west, gusting to 75km/hr. No snow is expected overnight. Another cloudy day is on deck for tomorrow. Some flurries will roll through, but accumulation will be limited. Up to 4cm's is expected. The alpine temperatures will rise to near zero by mid afternoon. Winds will settle down to moderate values with occasional gusts of 50km/hr. The freezing level will rise to 2200m once again. A mild system is expected to pass through our area over the week-end. Precip amounts have been dropping with each update, but we may still get a refresh tomorrow night.
Avalanche Summary
No new observations from today. There were numerous loose wet avalanches from yesterday's heat. All aspects/elevations had loose wet issues. The largest would have been sz2.
Snowpack Summary
Overnight lows have been high enough lately to prevent a solid freeze below treeline. By early afternoon the valley bottom snowpack is near isothermal and higher elevations are seeing moist snow on solar aspects. At treeline the surface varies from sun/temperature crust on solar aspects to fresh windslabs on lee features. The recent snow has been blown into the low areas where there is a crust underneath. No avalanches have occurred on this interface yet, but its likely there are isolated pockets of touchy windslab in crossloaded features. The alpine is a mix of windslab and wind disturbed, but still soft snow. Winds were variable today so expect to see windslabs of varying density on all aspects.
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.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.