Today was another day of touchy conditions. The strong winds have amplified the windslab problem as shown by the remote triggering witnessed today (see the avalanche observations section). Tread carefully and keep the objectives conservative.
Confidence
Fair - Intensity of incoming weather systems is uncertain
Weather Forecast
High winds and flurries are the theme for tomorrow. Snow amounts are limited, but the winds are expected to keep hauling out of the west. Today we found that ridge top winds and valley bottom winds were variable in direction. The same can be expected for tomorrow. As for the temps, no significant change there. A daytime high of -9.
Avalanche Summary
More natural activity was seen today. We suspect most of it happened last night as the winds picked up. The noted activity was alpine and treeline in elevation, north to northeast in aspect and moderate in slope angle. Of note today was a large avalanche remote triggered by forecasters. From 30m away we remoted the opposite side of the ridge on the western end of Tryste Chutes. The avalanche cleaned out three separate gullies and almost crossed the lake. Sz 2.5
Snowpack Summary
Not much new snow overnight. Nearly 10cm's fell at Burstall Pass. The news of the day (and days to come) was the wind. The high winds were also variable in direction. What we're left with is a widespread windslab problem in the alpine. On some aspects the snow has been pressed into a cohesive layer, and other aspects the snow has been blown into a firm windslab. The contributing factor with the new avalanche problem is the facet/surface hoar/sun crust interface layer. On today's snow study trip we visited the Superslope area and had all possible combinations of these snow types as an interface layer. No combinations were bonding well with the new slabs. This bad combination is widespread at alpine and open areas at upper treeline elevations. Below treeline still had well preserved soft snow.
Problems
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.
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.