Avalanche Forecast
Issued: Jan 20th, 2020 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.
shorton,
Avalanche Canada
Use caution on steep open slopes in the northern part of the region where triggering wind slab and deep persistent slab avalanches is a concern.
Summary
Confidence
Moderate - Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.
Weather Forecast
MONDAY NIGHT: Light snow with up to 5 cm, moderate wind from the south, alpine temperatures around -3 C.
TUESDAY: 5-15 cm of snow, strong wind from the south, freezing level around 1200 m with alpine high temperatures around -3 C.
WEDNESDAY: Cloudy with isolated flurries, light to moderate wind from the southwest, alpine high temperatures around -3 C.
THURSDAY: 5-15 cm of snow, strong wind from the southwest, freezing level up to 1800 m with alpine high temperatures around -1 C.
Avalanche Summary
On Sunday, several small (size 1) slabs were triggered by riders in the northern part of the region while small wet loose avalanches were reported around the Coquihalla. Several larger (size 2-2.5) natural slab avalanches were reported a few days ago during a period of intense snowfall.
Snowpack Summary
Relatively continuous light snowfalls over the past few days have brought recent storm totals to 25-50 cm in the north of the region. This recent snow has been heavily wind-affected in exposed areas at all elevations. The south of the region has received less snow and with warm temperatures has moist and crusty surfaces.
90-150 cm of snow currently sits above a weak layer of surface hoar from Christmas that professionals are tracking in the north of the region. It may be found at treeline and below on shaded aspects in sheltered areas. A deep persistent weak layer remains a serious concern at the bottom of the snowpack in the northern half of the region (e.g., Duffey, Hurley). It's made up of sugary faceted grains and a hard melt-freeze crust. This layer is most likely to be triggered in thin, rocky features where it exists closer to triggering forces on the surface.
There are currently no concerns about deep weaknesses in the snowpack near Coquihalla summit and elsewhere in the south of the region.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Wind Slabs
A week of continuous light snowfall and strong wind has left a variety of wind slabs at higher elevations in the north of the region. Some are old and stubborn, but newer, more reactive slabs may be found on north through east aspects in exposed areas in the alpine and upper treeline.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Two layers that cause concern in the northern part of the region include:
- A 90-150 cm deep weak layer of surface hoar layer found around treeline elevations in sheltered areas. It may still be triggered by a person in steep, sheltered openings around treeline.
- A weak layer buried near the bottom of the snowpack which continues to produce sporadic very large avalanches. This layer is most likely to be triggered in steep, thin, rocky areas in the alpine or upper treeline.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 21st, 2020 4:00PM
