Avalanche Forecast
Issued: Mar 15th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Deep Persistent Slabs and Cornices.
rgoddard,
Avalanche Canada
Solar input and warm temperatures begin to have their springtime effect on the snowpack.
Storm slabs may remain reactive for longer than expected.
Northerly aspects with little overhead hazard will offer the safest and best riding today.
Summary
Confidence
Moderate
Avalanche Summary
Tuesday was another day filled with avalanche reports. Our region saw multiple storm slab, wind slab, and deep persistent slab avalanches. Most of these were naturally triggered but a few caught some riders by surprise. The storm slab avalanches were found on all aspects and elevations and reached up to size 3 running at a depth of 70 cm. The wind slab avalanches reached up to size 3, found in the alpine, on aspects that ranged from southeast to north, and failed at a depth of up to 80 cm.
Snowpack Summary
A storm slab, 40 to 60 cm, overlies a variety of surfaces, which include surface hoar, 3 to 10 mm, on shady slopes at all elevations, wind-affected surfaces at treeline and above, and sun crust on sunny aspects. Moderate to strong southerly winds that accompanied this snow may have created wind slabs at higher elevations.
The mid-snowpack is generally strong but the lower snowpack is a different story.
The November facets are still prominent at the base of the snowpack. They are showing signs of improving but this layer remains a significant concern in rocky, shallow, or thin to thick snowpack areas at treeline and above.
Weather Summary
Wednesday Night
Clearing, no accumulation, winds westerly 10 to 15 km/h gusting to 30, treeline temperatures -9 °C.
Thursday
Mostly sunny with cloudy periods, no accumulation, winds southwest 10 km/h, treeline temperatures -5 °C with freezing levels up to 1500 m.
Friday
A mix of sun and cloud, no accumulation, winds southeast 10 km/h, treeline temperatures -4 °C with freezing levels getting up to 1600 m.
Saturday
Mostly sunny, no accumulation, winds southeast 10 km/h, treeline temperatures -5 to 0 °C with freezing levels getting up to 1700 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Don't let the desire for deep powder pull you into high consequence terrain.
- Use small low consequence slopes to test the bond of the new snow.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Be carefull around freshly wind loaded features.
Problems
Storm Slabs
A storm from earlier in the week brought us 40 to 60 cm of snow. This storm slab problem may remain reactive for longer than expected due to the uncertainty of how this new snow is binding with old surfaces.
Moderate to strong southerly winds that were associated with this past storm will have loaded lee features creating pockets of increased reactivity.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth, but large triggers such as cornice failures or smaller avalanches in motion have the potential to produce very large avalanches with surprisingly wide propagation. Suspect terrain for human triggering includes steep, shallow, and rocky terrain where the snowpack transitions from thin to thick.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Solar input could weaken cornices that have been building all season.
If the release, cornices could trigger weaker layers buried in the snowpack.
Aspects: East, South East, South, South West, West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 16th, 2023 4:00PM
