Snowfall with moderate westerly wind will increase the avalanche danger throughout the day. Forecast snowfall amounts are uncertain. Make observations and assess conditions continually as you travel.
Moderate to strong wind from the northwest switching direction to the southwest will load lee terrain features with the new snow. Wind slabs size and sensitivity to triggering will likely increase through the day.
Cornices have become noticeably larger and more overhanging in the past week.
Wednesday Night: Flurries, accumulation up to 5 cm, moderate to strong northwest wind, alpine high -4 C, freezing level 1200 m.
Thursday: Snow, accumulation 10-20 cm, moderate westerly wind, alpine high -2 C, freezing level 1200 m.
Friday: Flurries, accumulation 10-15 cm, moderate to strong southwest wind, alpine high -3 C, freezing level 800 m.
Saturday: Mix of sun and clouds, light to moderate northerly wind, alpine high -6 C, freezing level 900 m.
On Tuesday a few small wind slab avalanches (size 1) were observed in isolated lee terrain features. On Sunday there were reports of explosives controlled wind slab and storm slab avalanches to size 2 in the alpine. There was also a report of two size 3-3.5 naturally triggered deep persistent avalanches on a northwest aspects at 2600m. These would have run during or just after the storm on the weekend.
Extreme southwest wind leading into last weekend has scoured windward aspects, formed loaded pockets up to 150 cm deep in alpine lees and contributed to rapid cornice growth. Light to moderate amounts of new snow are beginning to obscure this lingering wind effect. Below 1900 m, recent snow overlies a thick crust and tapers quickly with elevation.
Weak faceted grains and crusts near the base of the snowpack have not been an active avalanche problem recently, despite significant new snow loads. They are still on our radar, especially in inland parts of the region.
