Avalanche Forecast
Issued: Mar 7th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
ahanna,
Avalanche Canada
630 am update
Greater snowfall overnight than expected. Reactive storm slabs are possible, be prepared to dial back your terrain choices if you observe more than 20cm of fresh snow.
The sun at this time of year can pack a punch so avoid exposure to cornices and watch for signs of warming in new snow on steep south aspects. Thin rocky areas remain a concern for triggering deeply buried weak layers, especially as temperatures warm up through the week.
Summary
Confidence
High
Avalanche Summary
No new avalanches have been reported since last week when the region saw numerous natural wind slab and cornice-triggered avalanches up to size 2.
On Tuesday our field team observed a size 3 deep persistent slab avalanche near Hankin that they estimated to be around a week old. The slab propagated across the full steep, rocky feature. This has been the latest of a consistent pattern of intermittent large deep persistent slab activity in the alpine. Observations from late February include a cornice-triggered size 2.5 at Hudson Bay and several explosive controlled size 2-3 near Ningunsaw.
Snowpack Summary
10-20 cm of soft snow sits over previously wind-hardened surfaces in the alpine. Sun crust or moist snow can be found on steep solar aspects.
Several crusts, layers of facets, or surface hoar can be found in the top 150 cm of the snowpack, but have not shown any significant avalanche activity or snowpack test results recently.
The lower snowpack consists of weak, basal facets which may become active with any rapid change or shock to the snowpack, such as heavy loading or dramatic warming.
Weather Summary
Tuesday night
Around 5 cm of new snow. Moderate to strong southeast wind. Alpine low -18ËšC.
Wednesday
Clearing to sunny in the afternoon. Moderate southeasterly wind. Alpine high -12 ËšC.
Thursday
Mostly sunny. Light to moderate southeasterly wind. Alpine high -8 ËšC.
Friday
A mix of sun and cloud. Strong southeasterly wind. Alpine high -5 ËšC.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Dial back your terrain choices if you are seeing more than 20 cm of new snow.
- Recent new snow may be hiding windslabs that were easily visible before the snow fell.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Conditions may have improved, but be mindful that deep instabilities are still present.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
New snow and wind are likely forming fresh wind slabs. Older wind slabs may require more time to bond with continued cold temperatures. Recent wind has varied in direction meaning wind slabs can be found on all aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Weak, sugary crystals at the bottom of the snowpack produced large avalanches just over a week ago. These avalanches are most likely to be triggered by large loads such as cornice falls. However, in shallow snowpack areas they can also be triggered by the weight of a person and could propagate out to deeper snow resulting in large, destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 8th, 2023 4:00PM
