Westerly winds, and small inputs of snow, will contribute to ongoing slab development through Friday.
Expect the hazard to rise through the weekend as a reasonably vigorous weather system brings snow - though amounts seem less certain east of the divide. Slab development can be expected at the upper elevations.
Expect to find small wind slabs in high alpine lee terrain. These slabs generally overlie faceted snow and a crust. As moderate to strong west and southwest winds continue through the weekend, expect incoming snow amounts of 5-20cm with mild temperatures to contribute to slab development.
Two persistent weak layers exist in the mid-pack in addition to the basal facets and depth hoar. Sporadic avalanche activity continues on these layers observed mainly in steep, thin snowpack locations of the alpine. As a rough guide: use more caution when the Feb 3 crust becomes thin or disappears.
Sunshine patrol reported triggering very small wind slabs that were 10cm deep.
Lake Louise and Visitor Safety staff travelled parts of the Pumpkin Traverse Thursday and reported ongoing wind transport, wind effect and triggered 2 size 1 slabs 10-20 cm deep on a crust in W facing alpine terrain.
Wednesday, a skier triggered a size 1 slab on the far skiers right on the Surprise Pass ski run. It was 30cm deep and 8m wide and ran for 30m at 2350m and was reported to have failed on facets
5-10cm of snow has come in over the last two days. Sun crusts and moist snow have been found on steep solar slopes while isolated wind slabs can be found in the high alpine. All of this sits on 10-15 cm of facetted snow over the Feb 3 crust that exists on all but N aspects above 2500m. Below this, weak facet layers can be found in the mid and lower snowpack. Generally, thin snowpack values for this time of the year: range is from 80 to 120cm at 2000m.
A moderate to strong, moist, westerly flow continues. Trace accumulations are expected as freezing levels fall from 1800m to valley bottom overnight Thursday.
Friday, a low pressure system will affect the area by mid-afternoon. 5-10 cm of snow can be expected through Saturday with the potential for larger amounts on west-facing slopes. Moderate to strong westerly winds
For more information see AvCan's Mt Wx Fx.
