A combination of new snow (20 cm+ by Sunday) and moderate to strong winds will cause the avalanche danger to increase. We have some uncertainty on how the deep persistent avalanche problem will react to this new load.
Dry loose avalanches are expected in steep and gulled terrain as the new snow accumulates over the old faceted surface snow. Ice climbers in particular should be wary of these sluffs in steep terrain.
New snow, combined with moderate to strong winds, will create fresh slabs at upper elevations. These new surface slabs are expected to bond poorly to the old surface snow.
The snowpack this season is very shallow, with weak facets and depth hoar on or near the ground. Typically, this kind of snowpack will not support much additional load, and we are concerned that these kinds of ground avalanches may reawaken if enough snow falls during this storm.
No new slab avalanches were observed or reported on Friday. Local ski hills have primarily reported loose dry avalanche activity, typically triggered by ski cuts.
5-20 cm of new snow and strong winds will create surface slabs that bond poorly to the underlying snow. The layer being buried on Jan 30 is a mix of crust, surface hoar and facets - none of which will bond well to the new snow. The snowpack is generally weak, with an old crust and depth hoar at the base, so any avalanches starting in the surface layers may step down to the ground and become larger.
A westerly flow will continue to bring precipitation to the forecast region over the weekend, with an additional 10 to 20 cm of snow expected by Sunday. Moderate to strong winds will accompany the new snow at ridge crests. Temperatures will gradually cool as an arctic air mass moves in, and by early next week, temperatures will plummet, with nighttime lows approaching -30°C.
