Locally heavy snowfall delivered 20cm more than forecasted. Reactive storm slabs are present where wind has stiffened the snow surface at Alpine and Tree-line elevations.
Gusty winds tonight and more snowfall Tuesday will increase the avalanche danger.
Avalanche control in Rogers Pass is anticipated Tuesday.
This crust-facet combo (Feb 3rd) was created by a rain event followed by an extended cold, clear period without snow earlier this month. 80-140cm now sits on the persistent weak layer. Human-triggered avalanches on this layer remain possible, and resulting avalanches could be very large in size.
Storm snow was accompanied by gusty SW winds. This built reactive soft slabs in lee areas. If triggered, these slabs may provide enough mass to trigger the deeper Persistent Weak Layer.
Natural avalanche activity in the hwy corridor picked up Mon morning with 20-30cm of snow and moderate SW winds. Avalanches to sz 2.5-3 were observed.
Last Thursday, we observed naturally-triggered size 3 slab avalanches from Catamount Mtn SE face and Mt. Leda NE face. These were both deep, likely failing on the Feb 3rd crust.
We continue to see daily reports in the region of human triggered avalanches on the Feb 3rd layer.
A 30-40cm storm slab now rests upon variable old surfaces: a thin suncrust on South & West aspects; previous wind effect from variable winds in open terrain; and settled powder in sheltered areas.
80-140cm of settled snow sits atop a sugary facet layer. These facets are not bonding well to the widespread, very firm crust from Feb 3rd. This crust is a significant persistent weak layer and will be the main layer of concern for the foreseeable future.
Continued unsettled weather, with flurries (locally heavy), gusty SW winds, and fluctuating freezing levels.
Tonight: Flurries, trace to 5cm, low -8°C, mod/strong S winds, FZL 700m.
Tues: Flurries, 5-10cm, Alp high -5°C, mod SW winds, FZL 1500m.
Wed: Mix of sun/cloud, isolated flurries, Alp high -8°C, light W winds, FZL 1300m.
Thurs: Sun/cloud, Alp high -4°C, light W winds, FZL 1500m
