The storm slated to hit Rogers Pass will heavily load the persistent weak layers and a natural avalanche cycle is expected.
Human triggered avalanches are very likely. Travel in avalanche terrain is not recommended.
The new snow overlays a buried persistent weak layer. This weak layer consists of surface hoar, facets and/or a suncrust. It will be most reactive where there is a settled, cohesive slab on top of a crust. The new snow load and warm temps may "wake up" this layer.
Fresh snow, strong winds and warm temperatures will be creating a new slab. This will be sitting on (yet another) weak layer of facets, expect this to be most reactive in immediate lee features. As the storm progresses the storm slab will become more widespread and reactive.
Weather models are struggling with snowfall amounts, but they do seem to agree either moderate or heavy snowfall is possible.
Tonight 16cm. Alpine low -4°C. Ridge winds SW gusting to 65km/hr. Freezing Level (FZL) 1400m
Sun 5cms. Alp high -3°C. Ridge wind SW 20km/h gusting 60. FZL 1500m
Mon 10cms. Alp high -4°C. Ridge wind SW20km/hr gusting 80. FZL 1400m
Tues 7cm. Alp high -3°C. Ridge wind SW 15km/hr. FZL 1400m
Artillery avalanche control is planned Saturday night.
Natural avalanches were observed in the park up to size 2.5 on Saturday. Avalanche activity is expected to increase overnight Saturday with the forecast for heavy snowfall.
Avalanches may run further than anticipated as the new storm slab sits on a layer of facets.
20-30cms of heavy new snow sits on a faceted upper snowpack from the previous cold snap. Surface snow is moist and sticky below 1450m.
A weak layer of surface hoar, facets and/or suncrust (Jan 30th) is 20-50cm down. This layer is still easy to pick out in pitwalls and produces results in tests. Watch out when this layer gets overloaded!
The mid & lower snowpack is well settled & strong.
