Avalanche Forecast
Issued: Jan 25th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
dsaly,
Avalanche Canada
Ongoing flurries and gusty winds continue to develop and build storm slabs.
Summary
Confidence
Moderate - Forecast precipitation (either snow or rain) amounts are uncertain.
Weather Forecast
SATURDAY NIGHT: Scattered flurries, 5 cm. Alpine low temperature -6 C. Southeast wind 10-20 km/hr. Freezing level 1000 m.
SUNDAY: Snow, 5-20 cm with the higher snowfall amounts favoring the Coquihalla. Alpine high temperature -3 C. South wind 20 gusting to 60 km/hr. Freezing level 1400 m.
MONDAY: Scattered flurries, 5-10 cm. Alpine high temperature -4 C. Southwest wind 20 gusting to 50 km/hr. Freezing level 1100 m.
TUESDAY: Flurries and snow, 5-20 cm. Alpine high temperature -4 C. Southwest wind 10-20 km/hr. Freezing level 1200 m.
Avalanche Summary
On Friday, small loose wet avalanches failed on south aspects at lower treeline and below treeline elevations.
Three very large (size 2-3) deep persistent avalanches failed naturally sometime between Thursday and Friday in the Duffey Lake area and near Gold Bridge. These avalanches occurred on east and northwest aspects around 2150-2200 m. Additionally, skiers remotely triggered a size 3 avalanche on a north aspect at 2100 m in the Duffey area and a size 1 deep persistent avalanche triggered by skiers while traveling along a skin track on a west aspect at 2050 m near Whitecap Mountain. Weak faceted grains and crusts near the base of the snowpack have periodically produced avalanches and continue to be a concern with additional loading from new snow and wind.
On Thursday, small (size 1) storm slab avalanches failed naturally on northerly aspects. Additionally, a machine triggered a size 2 avalanche on a steep slope below a road at 1800 m. Small (size 1-1.5) wet loose avalanche activity was reported below treeline.
Snowpack Summary
10-30 cm recent snow has settled with warm temperatures over a crust from January 20. Southerly winds have redistributed snow and formed windslabs in open areas and along ridgelines. Below 1600 m, rising freezing levels and rain produced moist surface snow and rapid snowpack settlement.
There have been two layers of concern in the northern half of the region (e.g. Duffey, Hurley). One is a weak layer of surface hoar buried about 100 cm deep that professionals are tracking at treeline in sheltered areas. The other is weak faceted grains and crusts near the bottom of the snowpack, that is most likely to be triggered in shallow rocky start zones. There are currently no concerns about deep weak layers in the south of the region (e.g. Coquihalla).
Terrain and Travel
- Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
- Watch for changing conditions today, storm slabs may become increasingly reactive.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
Problems
Storm Slabs
Continued flurries and gusty winds through the day will contribute to an ongoing storm slab problem. Expect to find the most reactive deposits in open areas and around ridge features at treeline and above.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
Weak layers in the northern part of the region were stressed by the recent storm and between Thursday and Friday deep persistent slab avalanches failed naturally and from skier traffic. Two layers have been a concern in the north including a 100 cm deep surface hoar layer in sheltered areas around treeline and weak, facetted snow near the bottom of the snowpack in shallow rocky start zones at higher elevations.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 26th, 2020 5:00PM
