Avalanche Forecast
Issued: Feb 17th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Deep Persistent Slabs and Wind Slabs.
jminifie,
Avalanche Canada
A fatal avalanche occurred west of Golden on February 16th. Details can be found in this report. The snowpack in this region is very complex and requires sophisticated snowpack analysis, careful terrain selection, and extremely diligent group management. The only way to minimize exposure is to select low angle, low consequence terrain and avoid areas where an avalanche could propagate widely.
Summary
Confidence
Moderate
Avalanche Summary
A size 3.5 avalanche that failed on a deep persistent weakness occurred west of Golden on February 16th and resulted in 2 fatalities. More details regarding this avalanche can be found in this report.
Our field team observed a size 3.5 avalanche in the Bull River area on an east through southeast aspect that started high and ran nearly 2000 m to the river. They estimated this avalanche to be 48hrs old. Given its size, this avalanche likely failed on a deep persistent weakness in the snowpack.
Explosive control throughout the region over the last 48hrs has resulted in persistent and deep persistent slab avalanches up to size 2 at alpine elevations on all aspects.
Snowpack Summary
Surface hoar continues to grow in open areas and a sun crust now exists on steep south aspects. Wind slabs of all ages still exist in exposed terrain and windward features are scoured. Good quality, settled powder snow can be found in sheltered alpine and treeline features. New snow will fall onto these existing surfaces over the weekend so pay attention to how that bond develops.
A variety of persistent layers still exists in the middle snowpack and continue to see avalanches occur on them periodically. Don't let these layers surprise you.
The lower snowpack contains a widespread layer of large, weak facets that is typically 80 to 150 cm deep. Snowpack depths at treeline range between 80 and 200 cm, with the shallowest depths found on the eastern edge of the Purcells.
Weather Summary
Friday night
Cloudy with flurries. 5 cm of new snow.
Saturday
Cloudy. 5 - 10 cm of new snow. Wind from the southwest at 20 km/h. Temperature -8ËšC.
SundayCloudy. 15 cm of new snow. Wind from the southwest at 25 km/h. Temperature -9ËšC to -4ËšC.
MondayCloudy. 20 cm of new snow. Wind for the southwest at 15 km/h. Temperature in in the alpine up to -4ËšC. Freezing levels up to 1500 m in some areas.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Use careful route-finding and stick to moderate slope angles with low consequences.
- Avoid rock outcroppings, convexities, and anywhere the snowpack is thin and/or variable.
- Be especially cautious as you transition into wind affected terrain.
- Expect slab conditions to change drastically as you move into wind exposed terrain.
Problems
Persistent Slabs
Large avalanches have been triggered on a 40 to 80 cm deep layer of surface hoar and facets that was buried in late January. This problem seems most concerning in the western and southern Purcells, where the layer is more deeply buried and primed for human triggering. Steep open slopes should be avoided.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
It remains possible for riders to trigger a weak layer of facets near the base of the snowpack. The most likely area to trigger it is in shallow areas with variable snow depths. Avoid thin and rocky start zones and select routes that avoid travelling through or under large avalanche paths.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Wind slabs of many vintages still linger in lee and cross loaded areas. They are likely getting harder to trigger but could still deliver a surprise. Use caution if you find yourself on a steep slope with stiff snow beneath you. As moderate amounts of new snow arrive over the weekend, new reactive wind slabs will develop.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 18th, 2023 4:00PM
