Avalanche Forecast
Issued: Mar 23rd, 2018 4:31PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs.
jmcbride,
Avalanche Canada
In the northern part of the region watch for new slab development at upper elevations. A buried surface hoar layer may also still be reactive in these areas. Meanwhile in the south, generally safe avalanche conditions are present at all elevations.
Summary
Confidence
Moderate - Due to the number of field observations
Weather Forecast
SATURDAY: Mix of sun and cloud. Ridge wind light, west. Alpine temperature near -8. Freezing level 1100 m.SUNDAY: Increasing cloud in afternoon. Ridge light to moderate, southwest. Alpine temperature near -7. Freezing level 1200 m.MONDAY: Cloudy, flurries. Accumulation 2-10 cm. Ridge wind moderate, southwest. Alpine temperature near -5. Freezing level 1400 m.
Avalanche Summary
Thursday there were reports of skier triggered size 1-1.5 wind slabs 10-30 cm deep on leeward, north-facing slopes at ridge top as well as sloughing below 1700 m in steep terrain.Last weekend, on Sunday a skier triggered avalanche was reported from around the Duffey on a north/northeast facing feature between 1900 and 2000 m. The size 2 avalanche failed on the March 8th surface hoar with a crown depth of 20 cm. And on Saturday two size 1.5 skier triggered avalanches were reported from steep northeast facing terrain at 2200 m on the Duffey. The slabs were up to 20 cm in depth, failing on the March 8th surface hoar.We also received a great MIN report on Saturday that details a size 3 skier triggered avalanche on the northwest face of Matier that likely occurred in the last few days. More details here.
Snowpack Summary
Thursday and Friday's storm snow (10- 20 cm) is sitting on a slippery crust that is present at all elevations on solar aspects. Low elevation polar aspects also have a crust, but treeline and alpine elevations feature a mix of large surface hoar and surface facets.In the north of the region, polar aspects (those that face north and east) are harboring cold snow and a tricky surface hoar interface buried early March is down 30 to 70 cm below the surface. The layer exists in the alpine and at treeline, but it is not everywhere. This layer has recently produced large human triggered avalanches in the north of the region as detailed above. This layer has not been reactive in the south of the region. Also in the north of the region a weak layer buried mid-February is about 50 to 80 cm below the surface and has been reactive in snowpack tests. The layer is composed of sugary facets, a sun crust on solar aspects, and surface hoar that is present at and below treeline. In the south of the region, around the Coquihalla and in Manning Park, a dusting of new snow overlies a recent crust that caps a well settled snowpack.
Problems
Storm Slabs
Moderate to strong southerly wind combined with recent snowfall is expected to form touchy storm slabs at upper elevations particularly in northern parts of the region. These slabs overlie the old surface of crusts and surface hoar.
Storm slabs are expected to be most sensitive to triggering in wind exposed terrain.Use caution on open slopes and convex rolls.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 24th, 2018 2:00PM
