Avalanche Forecast
Issued: Jan 25th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Cornices and Deep Persistent Slabs.
dsaly,
Avalanche Canada
Avalanche hazard will rise through the day, particularly in areas where heavy snow accumulates.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain.
Weather Forecast
SATURDAY NIGHT: Flurries, 5-10 cm. Alpine low temperature -4 C. Southeast wind 25-40 km/hr. Freezing level 1100 m.
SUNDAY: Snow, 15-25 cm. Alpine high temperature -1 C. South wind 35-55 km/hr. Freezing level 1400 m.
MONDAY: Scattered flurries, 5 cm. Alpine high temperature -3 C. South wind 20 gusting to 50 km/hr. Freezing level 1200 m.
TUESDAY: Sun, cloud, and isolated flurries. Alpine high temperature -2 C. Southeast wind 10-20 km/hr. Freezing level 1100 m.
Avalanche Summary
On Thursday and Friday, explosives easily triggered large (size 2) storm slab avalanches, producing 40-60 cm thick slabs with wide propagation. Large storm slab avalanches (size 2) failed naturally or were triggered by falling cornices.
Explosive control on Wednesday resulted in a very large (size 3.5) deep persistent slab on a west aspect the alpine, suggesting the deep persistent slab remained reactive and sensitive to new loads. With more loading on the way natural storm and deep persistent slab avalanches are serious concerns.
Snowpack Summary
10-25 mm precipitation in the last 24-36 hours fell mostly as rain below 1600 m. Above 1600 m, 30-100 cm recent snow sits over a rain crust from January 20 that was observed up to 2150 m. Wind over the past few days has been strong to extreme from the south, resulting in highly variable conditions in open terrain. Above 1800 m, strong winds continue to impact dry snow developing slabs and building cornices.
Weak faceted grains and crusts near the base of the snowpack continue to be a concern in inland parts of the region such as the Spearhead Range.
Terrain and Travel
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
- Extra caution is needed around cornices under the current conditions.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Dial back your terrain choices if you are seeing more than 25cm of new snow.
Problems
Storm Slabs
Storm slabs will develop as snowfall accumulates through Sunday. Wind will redistribute loose snow and further contribute to slab development. Recent rain has saturated the snowpack at lower elevations, however loose wet avalanches may still be triggered in steep and extreme terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Large cornice growth has been noted and reactive to skiers, more snow and wind will continue to build cornices.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Deep Persistent Slabs
Explosives testing continues to periodically trigger a weak layer of snow at the bottom of the snowpack (the latest being 2 avalanches on January 22, one a size 3.5). If triggered, this deep persistent layer will produce very large and destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 26th, 2020 5:00PM
