Avalanche Forecast
Issued: Nov 30th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
wlewis,
Avalanche Canada
Avoid avalanche terrain during heavy snowfall and strong winds. Minimize your exposure to overhead hazard as avalanches may run into lower elevations.
Summary
Confidence
Weather Forecast
TUESDAY NIGHT: Mixed precipitation continues overnight with 10mm expected. Freezing levels remain above 2000m overnight with strong southwest winds.
WEDNESDAY: 10-25mm mixed precipitation with strong southwest winds. Accumulations favour the Nelson area, however freezing levels will reach 2500m early in the day and remain high.
THURSDAY: Precipitation tapers early in the morning to clearing skies. Winds shift to moderate westerlies. Alpine high of -5, freezing level at 1800m, dropping to valley bottom overnight.
FRIDAY: Clear with moderate westerly winds. Freezing level remains below 1000m.
Avalanche Summary
On Saturday November 27, a size 2 storm slab was observed near Whitewater in a steep north facing treeline feature, unknown trigger.
On Friday, an avalanche cycle size 1-2 was observed from north facing alpine start zones. A size 1.5 skier accidental storm slab was also reported on the Mountain Information Network near Nelson. They noted a fast moving avalanche with wide propagation, supported by a hard bed surface.
Note that there are very few field observations in the Kootenay Boundary this early in the season. Backcountry users need skills in assessing conditions and decision making. If you go out in the mountains, please share your observations and/or photos on the Mountain Information Network.
Snowpack Summary
Overnight snow falls on a moist upper snowpack with around 30cm of recent storm snow. A series of rain crusts formed over the last week exist in the upper snowpack, each separated by up to 10cm of moist snow.
The mid-November crust is down 40-80cm and is up to 10cm thick. The lower snowpack is a series of crust and facet layers. At the bottom of the snowpack, up to 20 cm of faceted snow may be found.
Snowpack depths at treeline range from 50-100 cm, with alpine depths exceeding 150 cm in areas. Below 1700m, snowpack depths decrease rapidly. The entire snowpack will likely be saturated at lower elevations.
Terrain and Travel
- Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
- Watch for changing conditions today, storm slabs may become increasingly reactive.
Problems
Storm Slabs
Fresh, reactive storm slabs will build throughout the day with heavy new snow and wind. Large avalanches may run into lower elevations in areas of heavy snowfall.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 1st, 2021 4:00PM
