Avalanche Forecast
Issued: Mar 27th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wet Slabs, Wind Slabs and Persistent Slabs.
zryan,
Avalanche Canada
High overnight freezing levels and rain are expected to make the snowpack weak at lower elevations, with new wind slabs potentially forming up high.
Look for low angle, higher elevation objectives without overhead cornices. Plan your access and egress route carefully.
Summary
Confidence
Weather Forecast
SUNDAY NIGHT: Cloudy with snow/rain, 5-10 cm of accumulation above the rain-snow line. Alpine temperature around -1 C. Ridge winds 25-40km/h southwest. Freezing level 2100m.
MONDAY: Cloudy with flurries, up to 5-10 cm of accumulation above the rain-snow line. Alpine temperature around -3 C. Ridge winds 15-30 km/h southwest. Freezing level 1700 m.
TUESDAY: Mainly sunny. Alpine high of 3 C. Ridge winds 10-20 km/h southwest. Freezing level rising to 2300 m.
WEDNESDAY: Mainly cloudy with flurries. Alpine temperatures around -3 C. Ridge winds 15-40 km/h southwest. Freezing level rising to 1600 m.
Avalanche Summary
A few small (size 1) skier-triggered wind slabs were observed in the alpine on Saturday.
Two persistent slab avalanches were reported on Friday. One was a large (size 3) natural avalanche that was observed at 2000 m on an east aspect. The other was a result of explosive control on a cornice that initiated a large persistent slab avalanche (size 3) on a northeast aspect in the alpine. Explosive control also produced several large (size 2-3) cornices that did not initiate slab avalanches on the slopes below.
Two persistent slab avalanches were reported on Thursday, both on south-facing alpine slopes. One was a large (size 2.5) natural avalanche and the other was a small (size 1.5) slab remotely triggered by riders.
Snowpack Summary
Above 2000 m, up to 20 cm of recent snow and southwest winds may have formed small wind slabs in lee terrain features. Below 2000 m a refrozen crust can be found. This crust is expected to break down throughout the day with rain and warm temperatures. Below the crust, the top 10-30 cm of the snowpack is moist. At low elevations, the snowpack may become wet and isothermal.
A weak layer may be found around 50 to 100 cm deep. The layer consists of surface hoar crystals in treeline terrain on northerly aspects or weak faceted grains above a hard melt-freeze crust on sun-exposed slopes (i.e., east, south, west). It has been reactive between 1800 and 2300 m but given the recent rain, it is most likely to be triggered between 2000 and 2300 m. It should still be treated as suspect if you find it in your riding area.
The remainder of the snowpack is well-bonded.
Terrain and Travel
- The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
- Keep in mind that wet avalanches can be destructive due to their high density.
- If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
- Extra caution is needed around cornices under the current conditions.
Problems
Wet Slabs
Avoid exposure to large open slopes during intense rain, sun, or warming. High freezing levels and rain has triggered large wet slab avalanches on steep, open terrain features at treeline and below, especially where the snowpack sits over smooth rock slabs or grassy slopes.
Wet loose avalanche activity is expected on steep slopes below the freezing line where the surface snow is wet and unsupportive to your weight.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Wind slabs may be found in steep, lee terrain features in the alpine and exposed treeline. These wind slabs will be most reactive where they overlie a slick crust.
Warm temperatures may cause cornices to become weak. Cornice failures are dangerous on their own, but also have the potential to trigger larger avalanches on the slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer may be found around 50 to 100 cm deep. The layer is most likely to be triggered between 2000 and 2300 m, on all aspects. The likelihood of triggering this layer is decreasing, but the consequence of doing so would be high.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 28th, 2022 4:00PM
