Avalanche Forecast
Issued: Jan 11th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Loose Wet and Persistent Slabs.
wlewis,
Avalanche Canada
Avoid avalanche terrain throughout this storm. Deeply buried weak layers are likely to produce large and destructive natural avalanches.
Storm slabs will build at higher elevations, while rain and warm temperatures saturate the snowpack at lower elevations.
Summary
Confidence
Weather Forecast
The storm continues, a more intense front moves over the region bringing heavy rain and wind.
TUESDAY NIGHT: Rain begins overnight, delivering 20-45 mm below freezing levels at 2000 m, with mixed precipitation and snow above. Strong southwest winds continue.
WEDNESDAY: Freezing levels remain at 2000 m for the day, 20-50 cm expected over the day above the freezing level and heavy rain below.
THURSDAY: The front exits leaving clearing skies and light precipitation expected. Freezing levels sit around 1500 m, with light easterly winds.
FRIDAY: Partly cloudy with no precipitation expected. Winds return to strong southwest. Freezing levels at 1500 m.
Avalanche Summary
A widespread natural avalanche cycle is expected to occur at all elevations with the heavy rain, snow and wind with rising temperatures over Tuesday and Wednesday.
A natural slab avalanche cycle was observed near Squamish on Sunday. Avalanches were observed to size 3 on all aspects below treeline, and south facing aspects at treeline.
A size 2.5 naturally triggered slab avalanche was reported near Whistler, thought to have failed on the early December crust/facet combination. Small storm avalanches may step down to deeply buried weak layers such as this.
Snowpack Summary
30-60 cm of mixed precipitation has created a variety of surface snow conditions. Strong southwest winds have created deeper deposits at treeline and alpine elevations on north through east facing slopes. At lower elevations the precipitation fell as rain creating a saturated upper snowpack sitting over a melt freeze crust observed to 2000 m.
This recent precipitation adds to the 100+ cm of snow that has fallen since January 1, which may overly sugary faceted grains that formed during the cold spell in late December.
Around 150 to 250 cm deep, another weak layer of faceted grains may be found above a melt-freeze crust that formed in early December. The layer is most prominent between 1700 and 2100 m. Avalanches on this layer are large, but sporadic and isolated. The most likely place to trigger it would be in thin, rocky snowpack areas. The lower snowpack is well-settled and strong.
Terrain and Travel
- Minimize exposure during periods of heavy loading from new snow, wind or rain.
- Use increased caution at all elevations. Storm snow is forming touchy slabs.
- A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
- If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Storm Slabs
Fresh storm slabs will form with heavy precipitation above 2000m and warm temperatures. Greater loading will be found in wind loaded features, from southwest winds. Expect more reactive slabs where new snow sits over a crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Expect loose wet avalanches below 2000m. Surface snow will quickly lose cohesion with rainfall. Greater hazard exists in areas closer to the coast, where wet snow sits over a smooth crust.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Persistent Slabs
A deeply buried weak layer of sugary facets over a crust produced large naturally triggered avalanches during the last storm with rising freezing levels. Small storm avalanches may step down to these deeper instabilities producing large and destructive avalanches.
This problem is most likely to be triggered from thin or variable depth snowpack areas such as wind affected features, ridge crests, and near rocky outcroppings.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 12th, 2022 4:00PM
