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 Wind Slabs, Persistent Slabs and Loose Wet.
swerner,
Avalanche Canada
The March sun packs a punch and can quickly destabilize the snowpack. Natural avalanche activity may spike in the afternoon. Wind slabs may be primed for human triggering at upper elevations.
Summary
Confidence
Moderate
Avalanche Summary
No new reports on Wednesday.
On Tuesday, a natural size 2 wind slab and size 3 glide slab were reported both around 1300 m to 1500 m. A skier-triggered storm slab was also reported on Zoa. The slab was a size 1.5 and was triggered near the top of the slope with no involvement. It was 40 cm deep and slid clean on the underlying old snow surface. Check out the MIN HERE. Thanks for the report and happy to hear everyone was ok.
A natural persistent slab size 3 was reported on Tuesday but it's suspected that it failed Monday during the storm. This avalanche happened on a shady aspect at 1800 m, with the failure plane unknown but suspect an early March interface.
Natural and human-triggered avalanche activity may occur throughout the week with rising freezing levels and solar radiation.
Snowpack Summary
Surface snow will likely become moist on solar aspects during the day. Up to 40 cm of recent storm snow overlies a sun crust on solar aspects and a melt-freeze crust at lower elevations. Reports indicate that the slab may poor bond to the underlying crust, especially around 1500 to 1800 m. In sheltered areas, the new snow may sit above a spotty surface hoar layer. Recent strong southwest winds may have formed fresh wind slabs at higher elevations and cornices loom over ridgelines.
There are several crusts in the mid/lower snowpack. Their depth ranges from 50 to 150 cm. A large trigger, such as a cornice fall or a smaller avalanche in motion, could trigger a very large avalanche on one of these deeply buried weak layers.
Weather Summary
Wednesday Night
Clear. Alpine temperatures near -7. Wind from the west 10 km/hr and freezing level valley bottom.
Thursday
A mix of sun. Alpine temperatures near +1. Winds southeast 10-20 km/hr. Freezing level 1600 m.
Friday
A mix of sun and cloud. Alpine temperatures near +3. Wind southeast 10-20 km/hr. Freezing level 1700 m.
Saturday
A mix of sun and cloud. Winds 10-30 km/hr from the south. Alpine temperatures near +4 with freezing levels 1700 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
- Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
Moderate to strong southwest winds and 40 cm of recent storm snow may have formed new wind slabs on lee slopes at treeline and above. These may be easily human-triggered where the slabs have a poor bond to the underlying crust.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
There are several crusts in the mid-snowpack. Their depth ranges from 50-150+ cm. A large trigger, such as a cornice fall or a smaller avalanche in motion, could trigger a very large avalanche on one of these deeply buried weak layers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Strong solar radiation and rising freezing levels may weaken the surface snow creating wet loose avalanches from steep solar slopes.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 16th, 2023 4:00PM
