Avalanche Forecast
Issued: Mar 11th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs and Persistent Slabs.
TH,
Avalanche Canada
Despite limited inputs that can be expected to influence the snowpack this weekend, the avalanche hazard remains elevated.
Forecasters have very little faith in the buried persistent weak layers given the amount of avalanche observed this past week - despite the relatively benign weather.
Choosing terrain with modest slope angles, of limited slope size, and with limited overhead hazard remains the best way to manage your exposure while travelling.
Watch for hazard ratings to rise Monday with a warm, wet Pacific flow incoming.
Summary
Confidence
Avalanche Summary
We are still getting large settlements, or whumpfs, and occasional natural and skier triggered avalanches on the deeper weak layers in the snowpack.
A cornice triggered size 3 avalanche reported by Mt. Norquay ski hill occurred in the past 72hrs. Friday, the avalanche control team at Sunshine Village produced a sz 2 in steep terrain with explosives as well as a second sz 2 that was remote triggered by the same shot. On Saturday, SSV noticed a sz 2 cornice triggered east-facing slab in the surrounding alpine terrain.
Snowpack Summary
A sun crust is present on steep solar slopes at treeline and below while10-30 cm of soft snow can be found on northerly aspects. The various Jan PWL interfaces (sun crusts, facets, and surface hoar) are now down 40-80 cm. The weaker Nov. 16 basal facet layer is down 50-120 cm and continues to produce whumpfing and moderate to hard sudden collapse results in tests.
Weather Summary
Mainly cloudy skies with scattered flurries yielding 2-5cm of accumulation will persist overnight Saturday through Sunday with southwest winds in the light range and alpine temperatures warming a bit to between -10 and -15C.
Sunday evening snowfall will increase to bring 5cm overnight as winds increase to 40km/h and a strong Pacific flow of moisture begins.
10-20cm of snow is expected Monday with freezing levels approaching 2000m and winds increasing to beyond 50km/h.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Problems
Deep Persistent Slabs
Weaker facets and depth hoar remain at the bottom of the snowpack and inspire little confidence. Tests continue to show failures with a sudden collapse character and whumpfs are frequently observed while travelling. Be especially cautious in thin or rocky areas, where triggering is more likely. Cornice failures or smaller avalanches may act as a trigger for this layer so careful consideration of the slopes above your head is wise.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Three persistent weak layers formed in January are down 60-110 cm. Buried sun crusts found on steep solar slopes present the greatest concern for triggering on these interfaces however weak facets and isolated surface hoar can be found on the same interfaces on shaded aspects. A few avalanches on these layers have been observed in the past week.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 12th, 2023 5:00PM
