Avalanche Forecast
Issued: Jan 14th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
lbaker,
Avalanche Canada
Avalanche hazard is improving but be mindful that deep instabilities are still present. Uncertainty is best managed through conservative terrain choices.
Summary
Confidence
Moderate
Avalanche Summary
On Friday, snowcats remotely triggered numerous size 2.5 persistent slab avalanches on surprisingly low angel terrain from up to 150 m away. Avalanches occurred on a crust covered by surface hoar found up to 1900 on north and easterly aspects. See MIN for good photos and more details.
Several skier-triggered storm slab avalanches were reported up to size 1.5 throughout the region.
On Thursday, several natural loose wet avalanches, to size 1, were observed below treeline. Several explosive-triggered, size 1.5 storm slab avalanches were reported.
Thanks for the observations and please continue to post your reports and photos to the Mountain Information Network. It is really helpful for forecasters!
Snowpack Summary
20-30 cm of new snow and southerly winds have built storm slabs in lees at higher elevations. Below 1900 m storm brought a mix of rain and snow which will likely harden into a crust as freezing levels drop.
50 to 70 cm down is a crust formed in late December. Between 1900 and 1700 m surface hoar can be found above this crust which was reactive with the new snow load on Friday. This crust varies in thickness throughout the terrain and elevation. Uncertainty remains about the robustness of this crust above 2100 m.
There is a widespread weak layer of facets and depth hoar at the bottom of the snowpack. Snowpack depths around treeline are about 150-180 cm deep. The snowpack below treeline is very shallow and faceted.
Weather Summary
Saturday Night
Clear with cloudy periods. Southeast winds of 20 km/h. Ridgetop low-temperature -4C. Freezing levels fall to 500 m.
Sunday
Mainly cloudy isolated flurries, trace accumulation. Light variable winds gusting 20 km/h. Ridgetop high-temperature -2C. Freezing levels 1200 m.
Monday
Mainly cloudy with scattered flurries tapering off in the afternoon, 2-5 mm. Light variable winds gusting 20 km/h. Ridgetop high-temperature -3C. Freezing levels 1000 m.
Tuesday
Mainly cloudy with isolated flurries, 2-5 mm. Southwesterly winds increase from moderate to strong through the day, gusting 50 km/h. Ridgetop high-temperature -5C. Freezing levels valley bottom.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- Caution around convexities or sharp changes in terrain.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
20-30 cm of storm snow and southerly winds have built storm slabs in lees at higher elevations. Watch for wind-affected areas where deep pockets of storm snow feel stiff and may be more reactive to human triggering.
Be aware that slab avalanches could step down to deeper layers producing larger-than-expected avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A widespread crust formed in late December is found down 50 -70 cm. In many areas, this crust has slowly been healing however in isolated areas preserved surface hoar crystals overlie this layer and have recently resulted in large avalanches. This weak layer has been most reactive in the central and northern parts of the region, particularly around the Hurley and Birkenhead areas.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 15th, 2023 4:00PM
