Avalanche Forecast

Issued: Jan 15th, 2018 5:02PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Persistent Slabs.

Avalanche Canada jmcbride, Avalanche Canada

The snow pack is complex and human-triggered avalanches are still likely. Be extra cautious at lower elevations especially if temperatures begin to rise, or rain begins to fall.

Summary

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

TUESDAY: Mostly cloudy, flurries. Accumulation 5-10 cm. Ridge wind moderate, southwest. Temperature near 0. Freezing level 1500 m. Weak alpine inversion.WEDNESDAY: Cloudy, flurries. Accumulation 5-10 cm. Ridge wind moderate to strong, south. Temperature -2. Freezing level 1600 m.THURSDAY: Snow. Accumulation 10-20 cm. Ridge wind moderate to strong, southwest. Temperature near 0. Freezing level 1600 m.

Avalanche Summary

Sunday there were reports of natural loose wet avalanches to size 2.5 on solar aspects as well a size 3 deep-persistent, slab avalanche on a northerly aspect that's suspected to have failed on the December 15th layer.Very significant avalanche activity occurred in the region last Wednesday and Thursday. A smaller avalanche cycle, mostly affecting the recent storm snow was reported on Saturday. As temperatures warm lower elevations that have so far remained cool during the inversion, there is still an increased likelihood of triggering something large.

Snowpack Summary

Warm alpine temperatures have made the snow surface moist on slopes that face the sun. Below the surface, 40 to 60 cm of recent snow has settling into a cohesive slab on top of the reactive January 5th interface which consists of a crust/surface hoar combination on steep southerly aspects and pure surface hoar on remaining aspects. The late December surface hoar also remains reactive and is now down 80 to 90 cm below the surface. Adding to the complexity of the mid to upper snowpack is the mid-December surface hoar which is now 100 to 130 cm below the surface. This spooky interface continues to produce sudden snowpack test results and is most pronounced at treeline, but is also present below treeline. The overlying slab is now deep, dense and destructive. Two laminated crusts created by rain events in late November lay just below the mid-December interface, and may co-exist with facets. In shallow, rocky terrain the mid-December surface hoar and the late November crust seem to be reacting together which is a volatile combination.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Our snowpack is complex and has produced very large and destructive avalanches on up to four separate weak layers buried 50 to 120cm below the surface. Expert level knowledge and experience is required to safely venture into the backcountry.
Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Use conservative route selection, choose low angled and supported terrain with low consequence.Be mindful that deep instabilities are still present and have produced recent large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 4

Valid until: Jan 16th, 2018 2:00PM