Avalanche Forecast
Issued: Mar 13th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
ldreier,
Avalanche Canada
The ongoing storm will bring another 10 to 20 cm overnight and flurries during the day. The snowpack will need time to stabilize. A good day to make very conservative terrain choices and avoid overhead hazard!
Summary
Confidence
Weather Forecast
SATURDAY NIGHT: Cloudy, 10 to 20 cm new snow, 40 km/h westerly wind, alpine low -10 C, freezing level lowering to valley bottom.
SUNDAY: Mix of sun and cloud, up to 5 cm new snow, 40 km/h northwest wind, alpine high -6 C.
MONDAY: Mix of sun and cloud, trace of snow, 30 km/h westerly wind, alpine high -2 C.
TUESDAY: Mostly cloudy, 5 to 10 cm new snow, 40 km/h south wind, alpine high 0 C, freezing level rising to 900 m.
Avalanche Summary
A widespread natural avalanche cycle with storm slab avalanches up to size 2.5 started on Friday morning and continued on Saturday. Numerous wet slab avalanches up to size 3 and wet loose avalanches of size 2 were observed as well as several glide snow avalanches up to size 2.5. Explosives triggered storm slab avalanches up to size 3. A natural persistent slab avalanche of size 3.5 was observed south of Terrace.
Several natural glide snow avalanches and loose wet avalanches up to size 2 were reported on Wednesday. Some avalanche activity was observed on southerly aspects on Tuesday during the heat of the day. A few cornices were also triggered, which did not trigger slabs on the slopes below.
Snowpack Summary
Up to 120 cm of new snow fell since Thursday with strong to extreme southwest wind. The new snow may overly feathery surface hoar on northerly aspects and in sheltered terrain features around treeline or a melt-freeze crust on southerly aspects and below treeline.
Around 100 to 250 cm overlies a persistent weak layer buried in mid-February that may still be a concern in parts of the region. The layer consists of feathery surface hoar crystals in areas sheltered from the wind and sugary faceted grains that formed during February's cold snap. Avalanche activity on this layer has mostly occurred west of Terrace along Highway 16 in the past week, but the layer could still be of concern anywhere it exists.
There are currently no layers of concern in the mid and lower snowpack.
Terrain and Travel
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Be careful as you transition into wind affected terrain.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Storm Slabs
Up to 120 cm snow fell since Thursday, especially in the southern part of the region. The storm will bring another 10 to 20 cm new snow overnight combined with moderate to strong westerly wind. The new snow will be touchy, especially where it sits on surface hoar on northerly aspects and in sheltered terrain features around treeline or a melt-freeze crust on southerly aspects and below treeline.
Strong to extreme southwest wind has formed wind slabs during the storm which might be found farther down slopes than expected. The wind contributed to cornice growth and the additional load might lead to cornice failures.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Around 100 to 250 cm of snow may overly a persistent weak layer buried in mid-February. The likelihood of triggering the layer might stay elevated while the recent storm snow settles.
Failing cornices may trigger avalanches on this layer on the slopes below and create very large avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 14th, 2021 4:00PM
