Avalanche Forecast
Issued: May 4th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Loose Wet and Cornices.
mconlan,
Avalanche Canada
A very high freezing level and rain are creating dangerous avalanche conditions. Be aware of the various different types of avalanche problems that you may come across during spring weather. See more in the latest Forecasters' Blog.
Summary
Confidence
Moderate
Avalanche Summary
Many large to very large (size 2 to 4) wet loose, wet slabs, persistent slabs, and deep persistent slabs have been observed across the region over the past few days, being triggered by the high freezing level.
You should continue to expect wet loose or slab avalanches and cornice failures during periods of warm air, with associated sunny skies or rain. Avoiding steep slopes when the snow feels sloppy and avoiding cornice exposure are good travel habits.
The likelihood of triggering very large avalanches releasing on the buried weak layers described in the Snowpack Summary will increase with each day of warming during spring weather. This is particularly true for days without an overnight surface refreeze. Humans are most likely to trigger these layer in steep and rocky slopes where the snowpack is relatively thin.
Snowpack Summary
A moist snow surface is expected to mountain tops, which is unlikely to freeze overnight.
Various layers of surface hoar, facets, and crusts may be found around 50 to 150 cm deep in coastal areas and 30 to 50 cm in shallower snowpack areas in the north and east of the region.
Weak faceted grains may exist near the base of the snowpack, particularly in shallower snowpack areas.
Cornices are large and looming at this time of year and will weaken with daytime warming.
Weather Summary
Friday has a freezing level around 3000 m with 5 to 10 mm of rain. Saturday has light rain with a freezing level around 2000 m to 2500 m. Sunday's freezing level is around 1400 m with snow or rain expected.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.
- The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Avoid avalanche terrain during periods of heavy rain.
Problems
Deep Persistent Slabs
Weak layers may be found in the middle and near the base of the snowpack, which are reawakening with relatively mild weather and the variety of weather we receive during the spring. Small avalanches and cornice falls have the potential to trigger these deeper layers. Human triggered avalanches are most likely in steep, shallow, and rocky terrain where the snowpack is relatively thin.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Wet loose avalanche activity is expected during periods of rain. Limit your exposure to steep terrain when the snow feels sloppy and avoid any terrain traps.
Wet slabs are also possible, particularly where there is a buried hard melt-freeze crust.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices are large at this time of year and will become more prone to fail as they warm up with spring weather. Stay well back from them when on ridgelines and limit your exposure when travelling on slopes below them, as their release is unpredictable. Cornice falls could trigger very large slab avalanches on slopes below them.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: May 5th, 2023 4:00PM
