The persistent weak layer problem is particularly difficult to forecast, with high consequences if triggered.
Now is a good time to be making conservative terrain choices.
Last week's new snow overlays a buried persistent weak layer (PWL) that consists of suncrust, facets and/or surface hoar in some locations. Warm temps promoted the settling of a cohesive slab on top of this layer. Expect this slab to become more reactive during times of intense solar input.
High freezing levels the past few days have contributed to a weak snowpack at lower elevations. A cooling trend should decrease the sensitivity of this problem, but if the sun comes out expect this problem to re-activate.
Numerous wet loose and slab avalanches occurred in the past 3 days with daytime warming and solar input. These avalanches were up to size 3.0 and often gouged to ground at lower elevations where the snowpack had become isothermal.
Though the natural avalanche cycle is slowing today, human triggering remains possible.
Neighbouring operations have been seeing very large skier remote triggered avalanches on the facet interfaces down 30-80cm.
In the past 3 days, the top 5-10cm of the snowpack has undergone melt-freeze cycle on all aspects below treeline, and on solar aspects into the alpine. The 40cm of storm snow that fell last week sits on a very faceted (sugary) upper snowpack.
A weak layer of surface hoar, facets and/or suncrust (Jan 30th) is 50-80cm down. Feb 16 is another PWL (facets/crust/surface hoar) down 30-40cms. Both of these layers are reactive to human triggering.
A cold front will transit the interior on Monday, bringing light precipitation.
Tonight Mainly cloudy. Alpine high -4°C. Light North ridge winds. Freezing level (FZL) 1300m
Mon Mix sun/cloud with flurries. Trace of precipitation. Alp high -5°C. Light S wind. FZL 1500m
Tues Mix of sun/ cloud. Alp high -6. Light S wind. FZL 1500m
Wed Mainly cloudy. 5cm snow. Alp high -7°C. Light SW wind. FZL 1400m
