Avalanche Forecast
Issued: Jan 24th, 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
Triggering avalanches remains likely where new snow and wind has formed slabs, especially in open terrain at higher elevations.
Summary
Confidence
Moderate - Uncertainty is due to difficult to forecast freezing levels.
Weather Forecast
FRIDAY NIGHT: Flurries, 5 cm. Alpine low temperature -3 C. South wind, 25-45 km/hr. Freezing level 1200 m.
SATURDAY: Flurries, 5-10 cm. Alpine high temperature -2 C. South wind 25-45 km/hr. Freezing level 1400 m.
SUNDAY: Snow, 20-40 cm. Alpine high temperature -1 C. South wind 35-55 km/hr. Freezing level 1300 m.
MONDAY: Scattered flurries, 5 cm. Alpine high temperature -4 C. Southwest wind 20 gusting to 50 km/hr. Freezing level 1200 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
40-60 mm in the last 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 snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Extra caution is needed around cornices under the current conditions.
Problems
Storm Slabs
Intense loading from new snow developed touchy storm slabs at upper elevations. With ongoing flurries and strong to extreme winds, expect to find reactive slabs and growing cornices at treeline and above. At lower elevations rain saturated the snowpack, 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, naturally failing cornices have triggered storm slabs on slopes below.
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 25th, 2020 5:00PM
