Avalanche Forecast

SATURDAY NIGHT: Mostly cloudy with isolated flurries, accumulation 2 to 5 cm, light north wind, alpine temperature -10 C.

SUNDAY: Mix of sun and cloud, light northwest wind, alpine temperature -10 C, freezing level 900 m.

MONDAY: Clear skies, light west wind, alpine temperature -10 C, freezing level 1000 m.

TUESDAY: Cloudy with snowfall, accumulation 2 to 5 cm, moderate southwest wind, alpine temperature -6 C, freezing level 1200 m.

On Friday, explosives triggered cornices and 20 cm slabs within the recent storm snow, producing small (size 1 to 1.5) up to large (size 2) avalanches. The avalanches were on west to north aspects and at alpine elevations. A persistent slab avalanche was triggered by a rider in the northern part of the region, likely releasing on the surface hoar layer described in the Snowpack Summary. The avalanche was large (size 2), in alpine terrain, and on a northerly aspect.

Natural avalanche activity is expected to taper with a calmer weather pattern. The exception is during periods of strong sun, where the storm snow on sun-exposed slopes could moisten and form loose avalanches. Human triggering of the storm and wind slabs may remain possible this weekend until the snow bonds to previous surfaces.

Thursday's storm dropped around 15 to 25 cm of snow across the region. The snow fell with strong south to southwest wind, forming wind slabs in lee terrain features at treeline and alpine elevations. In sheltered terrain, the snow is likely consolidating into a storm slab and starting to bond to underlying surfaces.

A weak layer of surface hoar crystals and/or faceted grains may be found around 40 to 80 cm deep on northerly aspects at treeline and lower alpine elevations. The layer may have been destroyed by strong wind immediately before burial on February 22nd, but it may still exist in sheltered terrain features. Where it exists, it has been reactive in some snowpack tests but not others, suggesting spatial variation. This persistent weak layer warrants investigation and a conservative terrain use strategy. Check out the latest forecaster blog that offers a deeper dive into these conditions.

In the northern part of the region (i.e., Duffey/Hurley/Goldbridge), a deep instability may linger at the base of the snowpack. It has not produced an avalanche since February 17th. Human-triggering is unlikely, though if one were to trigger the layer, it would likely be in a thin, shallow, rocky spot. A large load, such as from a cornice fall, or rapidly changing weather have the potential to trigger this layer.

• Carefully evaluate steep lines for wind slabs.
• Surface hoar distribution is highly variable. Avoid generalizing your observations.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Pay attention to cornices and give them a wide berth when traveling on or below ridges.
• Minimize exposure to sun-exposed slopes when the solar radiation is strong.