Avalanche Forecast

On Thursday storm slabs were reported human triggered to size 1. Natural avalanches were reported to size 2.5 thought to occur during heavy snowfall or wind loading. Operators reported rapid loading due to winds at higher elevations but observations were limited due to visibility and weather. We expect a natural cycle to have occurred, especially in wind loaded features and that human triggered avalanches were also likely.

A few very large (size 3.5 to 4) deep persistent slab avalanches were also observed over last week, which likely occurred during the very windy arctic outflow event.

Storm totals have reached 30-80 cm. Variable winds have redistributed this into deeper deposits on many aspects. This storm snow sits over wind effected surfaces, a thin sun crust on steep south facing slopes.

Below this interface, around 50-90 cm deep, a layer of small surface hoar from exists in lower elevation sheltered areas and more widespread faceted (sugary) snow and heavy wind effect from the late February Arctic blast. Reports suggest this interface is beginning to bond and strengthen.

The remainder of the mid-snowpack is considered generally strong with a small surface hoar layer buried over 1 m deep from mid February. Reports suggest this layer is bonding well but most likely found around treeline elevations in areas sheltered from the wind.

Large and weak facets that formed in November are found near the base of the snowpack. Although the likelihood of triggering this layer is low at this time, the consequence of doing so remains very high. This layer is most likely to be human-triggered in thin, rocky slopes at alpine and upper treeline elevations.

Friday Night

Cloudy with easing flurries. Light southwest winds. Freezing levels below valley bottom.

Saturday

A mix of sun and cloud. Light to moderate easterly winds. Freezing levels below valley bottom, alpine high of -6 °C.

Sunday

A mix of sun and cloud. Light to moderate east winds. Freezing levels below valley bottom, alpine high of -8 °C. Possible flurries.

Monday

Mostly cloudy. Moderate southerly winds. Freezing levels below valley bottom, alpine high of -5 °C. Flurries possible.

More details can be found in the Mountain Weather Forecast.

• Continue to make conservative terrain choices while the storm snow settles and stabilizes.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
• Minimize exposure to sun-exposed slopes when the solar radiation is strong.