Avalanche Forecast
Issued: Dec 28th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
lbaker,
Avalanche Canada
Conditions may have improved but be mindful that deep instabilities are still present at higher elevations. If triggered wind slabs may step down to deeper layers resulting in large destructive avalanches.
Summary
Confidence
Avalanche Summary
On Tuesday, recreationists reported experiencing a few large whumpfs. Explosives control produced several size 2.5 slab avalanches on deep weak layers. This is good evidence that with the deep persistent weak layers are still with us and will result in large destructive avalanches with a big trigger. Manage uncertainty with good travel habits to have a safe day.
On Monday, evidence of a natural avalanche cycle, both wet slab and wet loose avalanches, was observed on all aspects at all elevations. Avalanches were up to size 3 and likely occurred during the rain event Sunday night.
Please continue to post your observations and photos to the Mountain Information Network.
Snowpack Summary
10-20 cm of low-density snow sits over 40-60cm of moist snow. A melt-freeze crust is found down 25 cm to 1900 m. New snow has been redistributed by strong southerly winds into deep pockets in alpine lees. A melt-freeze crust has formed below 1700 m.
The new snow covered a layer of weak and unconsolidated snow produced by the recent cold weather. The winter snowpack is not as deep as usual, and along with a cold and dry early winter, the lower snowpack consists of weak, unconsolidated facets and depth hoar crystals. Snowpack depths average 50-200 cm at treeline. This weekend's warm temperatures and rain shrank snowpack below 1500m making travel at lower elevations difficult.
Weather Summary
Wednesday Night
Isolated flurries, trace accumulation. Southwesterly winds 20 km/h. Ridgetop low temperature -6 C. Freezing levels valley bottom.
Thursday
Mostly cloudy with isolated flurries, trace accumulation. Southerly winds 20 km/h gusting 40 km/h. Ridgetop high temperature -1 C. Freezing level valley bottom.
FridayCloudy with flurries, 2-5 cm. Southerly winds 30 km/h. Ridgetop high temperature 0 C. Freezing level 700 m.
SaturdayIsolated flurries, trace accumulation. Southwesterly winds 20 km/h. Ridgetop high temperature 0 C. Freezing level 600 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Wind Slabs
Strong southerly winds have redistributed 35 - 50 cm of new snow into deep pockets at higher elevations. Be especially cautious transitioning into wind-loaded terrain, more reactive deposits lurk in leeward features.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The winter snowpack is not as deep as usual, and along with a cold and dry early winter, the lower snowpack consists of weak, unconsolidated facets and depth hoar crystals. With weak basal layers, a cautious approach to large open terrain features is required especially around rocky or thin areas.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 29th, 2022 4:00PM
