Up to 40 cm of new snow combined with strong to extreme winds will elevate hazard to High in the alpine. Model guidance varies on snowfall amounts, so err on the side of caution.
A facet interface from late January is now buried 100–180 cm deep. We continue to see hard, sudden test results on this layer in some areas. This problem will have to adjust to the new load and will produce large avalanches if triggered.
New snow sitting on top of crusts could create fast conditions for loose dry avalanches on Wednesday.
Incoming snow will build storm slabs at tree-line and below. Accompanying strong SW wind will build wind-slabs in lee terrain in the alpine Wednesday. Sensitivity will depend on snow fall amounts, but will likely increase as the storm continues.
Sunshine patrol reported ski cutting small loose dry avalanches in the new snow (13cm as of Tuesday @ 3pm), running quickly on crusts. Lake Louise patrol reported triggering size 1 avalanches, about 10 cm thick, in immediate alpine lees terrain on Tuesday. No other avalanches were observed or reported.
New snow has begun, with about 5 cm so far. Above 2200 m, it overlies last week’s storm snow. Below 2200 m, it falls on the Mar 20 rain crust, with additional sun crusts on solar aspects. The Mar 20 crust thickens with decreasing elevation. Fresh wind slabs will build through Weds with new snow and strong SW winds. The January 24 facet layer is buried 100–180 cm deep at tree-line and in the alpine, with some tests still producing hard, sudden results.
15 - 40 cm of snow is expected by end of day Wednesday. Temperatures will remain cool, with valley bottoms near 0 and ridgetop temperatures around -12. Freezing levels are forecast to remain at or below the surface, so precipitation should fall as snow, though some uncertainty remains. Strong southwest winds at 3000 m, up to 80 km/h, are expected to accompany the storm.
