Avalanche Forecast
Issued: Apr 6th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Loose Wet and Cornices.
swerner,
Avalanche Canada
Recent storm snow combined with significant warming and solar radiation are driving the avalanche hazard, especially by the afternoon.
Check out the Forecaster Blog for additional details.
Summary
Confidence
Weather Forecast
Thursday: A mix of sun, clouds, and very WARM. Freezing levels rise to 2900 m by the afternoon. Alpine temperatures +3C and ridgetop wind moderate to strong from the southwest.
Friday: No overnight refreeze and WARM. The freezing level holds at 2900 m but should start to drop by 4 pm. Cloudy with a mix of rain and snow up to 15 mm. Ridgetop winds strong from the southwest.
Saturday: Cloudy and cold with new snow up to 10 cm. Freezing levels drop to 700 m and ridgetop winds switch to the northwest.
Avalanche Summary
On Tuesday, numerous natural, explosive, and rider-triggered avalanches were reported up to size 3.5. Most of these avalanches failed within the recent storm snow, however, some of the larger ones were reported as a persistent slabs that failed on a buried crust.
Continued warm temperatures solar radiation will likely trigger a natural avalanche cycle on Thursday and Friday.
Snowpack Summary
By Thursday afternoon, wet snow surfaces may exist to mountain top on most aspects leaving only high North facing terrain with some dry snow.
20 to 40 cm of recent storm snow has buried multiple crusts in the upper snowpack. Moderate to strong west/ southwest has redistributed some new storm snow in exposed high elevation terrain forming wind slabs and developing large cornices.
The new snow brings 60-80 cm above the crust from late March. This crust is present on all aspects up to an elevation of 2500 m.
The early-December rain crust is approximately a metre off the ground. Large slab avalanches failed on this interface last week following a rain and warming event. This layer may be active over the next two days of warm weather.
Terrain and Travel
- Avoid all avalanche terrain during periods of intense solar radiation.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Cornices become weak with daytime heating or solar exposure.
- Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
Problems
Persistent Slabs
60-80 cm of recent storm snow sits above a crust at treeline and above. Warming and solar radiation will likely consolidate the new snow into a reactive slab, producing large avalanches. Avalanches may start as dry slabs in the alpine but entrain wet snow and run into below treeline elevations.
The warm-up last week produced some deeper and bigger avalanches that ran to the valley bottom. These failed on a December rain crust that exists a metre off the ground. There is a lot of uncertainty with this interface and whether it will wake up or not over the next two days.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Sun and warm temperatures will weaken the snow surface on sun-exposed slopes, creating wet avalanches. Watch for wet and heavy snow and be aware of overhead exposure to big sunny slopes.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Springtime cornices are large and unpredictable. The sunshine can pack a punch and lead to cornice failures. Give them a wide berth when travelling at ridge crest and avoid overhead exposure.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 7th, 2022 4:00PM
