Watch for reactive new wind slabs on aspects lee to southwest through northwest winds. Any dry new snow will be especially sensitive to seeing the sun for the first time when it comes out Sunday.
Strong southwest winds during the storm ease and switch to northwest overnight. Watch for wind slabs in lee terrain features in the alpine and upper treeline.
Saturday night: Clearing skies. Moderate northwest wind. Alpine low -12 C. Freezing level valley bottom.
Sunday: Sunny. Northwest wind easing to light. Alpine high -7 C. Freezing level 500 m.
Monday: Mix of sun and cloud. Light northwest wind. Alpine high -5 C. Freezing level valley bottom.
Tuesday: Mix of sun and cloud. Light northwest wind. Alpine high -8 C. Freezing level valley bottom.
A widespread storm slab avalanche cycle up to size 2 was observed Friday mostly on northeast aspects 1900-2100 m.
Reports of deep persistent avalanches have been periodically coming in from the western boundary area over the past few weeks and most recently on Friday in the southwest Valhallas. They are generally triggered by very large loads (cornice falls or vehicles) or from shallow, rocky snowpack areas. Loading from new snow and rain will further stress these buried weak layers where they exist.
Above 2000 m, storm totals of 10-30 cm have been blown into wind slabs by strong southwest, followed by northwest, winds. Below, up to 10 cm of new snow may sit on a thick crust.
A layer of surface hoar is buried 100-150 cm below the surface in sheltered areas around treeline but has not been associated with avalanche activity recently. Weak basal facet/crust layers are particularly noteworthy in the western Boundary area. The few recent avalanches associated with this problem have been triggered either by very large loads or from shallow, rocky snowpack areas.
