Regions
Banff Yoho Kootenay.
Concern remains for the persistent slabs however natural activity has been limited to soft windslabs in the alpine. A new weather pattern will change the wind direction and affect future windslab development.
Weather Forecast
The skies will clear Sunday morning and winds have already begun to slack and shift to the NW. The more stable pattern that we are entering into will see temperatures drop to -10 to -15 values at treeline for the 3 day period at least. Watch for wind speeds to increase in to the moderate range for Monday.
Snowpack Summary
Below 2500m up to 50 cm of snow lies over the 1127 crust. Another crust (1123) can be found below this and both of these now overlie the 1031 crust that sits 30 to 50cm above the ground. Soft new windslabs are developing in the alpine where up to 60cm can be found over the 1127 wind effect and the 1031 facet crystals are 40 to 50 cm above ground.
Avalanche Summary
A tour to the Ferris Glacier saw very little recent avalanche activity. One sz 2 natural windslab was seen out of a snowfield between two NE facing cliff bands at around 2700m. This freshly formed slab appeared to be 40 to 50 cm deep and likely was a result of wind driven sluffs spilling over the cliffs above.
Confidence
Due to the number of field observations
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.