Avalanche Forecast
Issued: Apr 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 Deep Persistent Slabs.
JMackenzie,
Avalanche Canada
Another warm day is forecast for Sunday with high freezing levels and a chance of rain later in the day. Watch for solar radiation, and then rain, to decrease stability as the day warms up. Pay attention to overhead terrain that may be in the sun at the start of your day. Early starts and finishes are key! Its heading to spring!!!
Summary
Confidence
Moderate
Avalanche Summary
One size 2.5 slab avalanche was observed today in the Murray Twins area on a NE aspect at 2400m. This slide occurred in the past 24hrs and overran debris from previous adjacent avalanches.
Snowpack Summary
Dry snow remains on polar aspects at higher elevations, with recently formed wind slabs in lee and cross-loaded terrain. Solar aspects are primarily crusty in the morning and becoming moist with daytime heating and radiation. Travel at lower elevations is fast and easy in the mornings on a thick melt-freeze crust from the rain last week. Forecasters continue to track persistent weaknesses down anywhere from 40 to 100cm on polar aspects. These weaknesses are highly variable in nature and travelers should take the time to dig down and evaluate the snowpack frequently. Also, the lingering deep persistent slab problem is still alive and well. The deep weak layer of facets and depth hoar have become quite active in the increased heat, and this is expected to continue, with large destructive avalanches possible.
Solar radiation has a big influence on stability at this time of year. Stability will quickly deteriorate on solar aspects as temperatures warm up. These decreases will be most apparent on steep solar aspects, especially in thin rocky terrain. Early starts and finishes that avoid the heat of the day are key. Also pay close attention to what aspect you are on or under, and be mindful of cornices.
Weather Summary
Sunday should be mainly cloudy with a slight chance of flurries/rain in the morning, and more organized precipitation arriving late in the afternoon. Winds will be moderate from the SW, with temperatures climbing to +2C at ridgetop. Freezing levels are expected to be near 2350m, so any precip will fall as rain below this elevation.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid steep slopes when air temperatures are warm, or solar radiation is strong.
- Cornices become weak with daytime heating or solar exposure.
Problems
Wind Slabs
Wind slabs in the recent storm snow should be expected at treeline and above. Evaluate the bond with the underlying snowpack which is highly variable. There is currently a lot of uncertainty with the characteristics of this interface.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Persistent Slabs
The persistent layer down 1m has been active due to recent snow loads. It also appears to be sensitive to heat.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Shallow snowpack areas are an area of special concern, especially with intense solar radiation and/or daytime heating.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 16th, 2023 4:00PM
