Avalanche Forecast
Issued: Mar 18th, 2017 4:50PM
The alpine rating is Storm Slabs and Persistent Slabs.
, the treeline rating is , and the below treeline rating is Known problems includeRapid loading, warm temperatures and strong wind are a recipe for HIGH danger in the alpine. Avoid avalanche terrain and stay well back from runout zones.
Summary
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
We'll see lingering flurries on Sunday as it cools down significantly. Clearing Monday onwards.SUNDAY: Broken skies with isolated flurries / moderate to strong west wind / Alpine temperature -8 / Freezing level 800mMONDAY: Increasing cloud in the afternoon and some scattered flurries / Light east wind / Alpine temperature -6 / Freezing level 1200mTUESDAY: Isolated flurries / Light to moderate southwest wind / Freezing level 1500m
Avalanche Summary
On Saturday morning a Size 2 storm slab (crown height 15-20cm) was remote-triggered on a bootpack path in the backcountry near Golden. The past few days warm and wet weather have seen a natural avalanche cycle to size 3.5 from a variety of aspects and elevations. In the wake of the storm on Saturday expect the likelihood of triggering an avalanche to remain elevated.
Snowpack Summary
Heavy wet snow (15-20 cm in 12 hours) and moderate southerly winds started late Friday and continued through Saturday. Temperatures also warmed up significantly with rain up to 2200m. The end result: Widespread storm slabs and wind slabs at treeline and above with significant cornice growth as well.This storm snow (totals of 30-70cm) sits on older windslabs (or soft slabs) at treeline and above. Below 1800m, the new snow sits on a melt-freeze crust from last week's warm storm, and reports so far are that the new snow is bonding well to the old crust. The persistent weakness buried late-February is now down 90-140cm, and is composed of weak facetted crystals on a thick rain crust as high as about 2000m and facets on sun crust on steep southerly aspects. This layer has produced easy-moderate results in recent snowpack tests and has proven especially reactive on steep southerly aspects.Several deeper persistent weaknesses also remain a concern, including surface hoar buried early-February and mid-January (primarily in the northern Purcells). The november crust and basal facets are still reactive in shallow, rocky start zones.
Problems
Storm Slabs
More warm storm snow on Saturday combined with moderate to strong wind created a storm slab problem. These storm slabs will be particularly deep and touchy on slopes loaded by southerly wind.
The new snow will require several days to settle and stabilize.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Various persistent weaknesses strewn throughout the snowpack create the potential for large step-down avalanches. Heavy loads such as a smaller storm/wind slab avalanche or a cornice fall increase the likelihood of triggering these layers.
Avoid steep convexities or areas with a thin or variable snowpack.Be aware of the potential for large avalanches due to the presence of deeply buried weak layers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 19th, 2017 2:00PM