Avalanche Forecast
Issued: Jan 23rd, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Wet, Deep Persistent Slabs and Cornices.
ahanna,
Avalanche Canada
It seems the snowpack has been largely resilient to warm temperatures over the weekend. But don't underestimate the power of the sun on Monday. Minimize exposure to steep sun exposed slopes, especially if they have cornices overhead.
Summary
Confidence
Weather Forecast
The region now sits under a warm ridge of high pressure which is expected to persist through the week bringing very high freezing levels and sun.
Sunday night: Partly cloudy, light NW wind, freezing levels around 2500 m with an inversion.
Monday: Sunny, light NW wind, freezing levels around 2000 m with an inversion.
Tuesday: A mix of sun and cloud, light W wind, freezing levels around 2300 m with an inversion.
Wednesday: Sunny, light NW wind, freezing levels around 2600 m with an inversion.
Avalanche Summary
Avalanche activity associated with the warming over the weekend has been minimal. On Friday and Saturday, small loose wet avalanches were observed out of steep south and east facing terrain and explosive control work produced cornices up to size 2.5. On Friday, natural and skier triggered wind slabs size 1.5-2 were reported.
Last week, some very large natural avalanches took out mature timber and left mountainous piles of debris down to very low elevations. Check out the insane photos of the size 4 in this MIN from January 15th. We were anticipating the possibility of avalanches of this scale during current warm weather but as of writing, this activity has not materialized. Parts of the region are currently under a Special Public Avalanche Warning (SPAW). Check out this new blog post for additional information.
Snowpack Summary
At mid elevations, moist surfaces or a thin crust can be found on solar aspects, while most aspects at upper elevations remain dry. Wind slabs linger in exposed high elevation terrain, mainly on north and east aspects.
The widespread and robust January 16 melt-freeze crust sits up to 30 cm deep, as high as 2100 m. There have been some observations of surface hoar sitting on the crust on polar aspects at treeline and in the alpine north of Pemberton but this does not appear to be widespread. At lower elevations, the previously rain soaked upper snowpack is moist or wet and may be capped with a breakable crust.
The depth of the early December crust/facet layer is highly variable through the region but appears to be typically down 100-200 cm. Some operators are showing the depth as low as 60 cm in shallow snowpack areas and as deep as 3 m in wind loaded terrain. The weak layer is most prominent between 1700 and 2100 m. The layer continues to be a concern through the current period of major warming and sun. The most likely place to trigger it would be in thin, rocky snowpack areas where it is shallowest.
Terrain and Travel
- Cornices become weak with daytime heating or solar exposure.
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
- Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
Problems
Loose Wet
Extra caution is necessary around steep south facing slopes when the sun is strong.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
An old persistent weak layer buried deeply in the snowpack has been dormant recently but is being tested by the sustained warming event. Large loads such as cornice falls or smaller avalanches have the highest potential to step down to a deeply buried weak layer.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Large cornices have been reactive to explosives in recent days. Strong solar radiation can cause cornices to fail naturally.
Aspects: North, North East, East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Jan 24th, 2022 4:00PM
