Avalanche Forecast

Issued: Jan 18th, 2018 4:45PM

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

Avalanche Canada jmcbride, Avalanche Canada

Snow and wind are expected to continue however, there is some uncertainty as to just how much snowfall some areas will see.  If trail breaking is deep and heavy, storm slabs have likely formed - stick to moderate terrain.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Southern parts of the region can expect to see higher snowfall amounts than northern areas.TONIGHT: Flurries. Accumulation 1-5 cm. Ridge wind moderate, southwest. Temperature -7. Freezing level 800 m.FRIDAY: Cloudy, snow. Accumulation 5-15 cm. Ridge wind moderate, southwest. Temperature -3. Freezing level 1200 m.SATURDAY: Cloudy, snow. Accumulation 2-10 cm. Ridge wind moderate, southwest. Temperature -4. Freezing level 1000 m.SUNDAY: Cloudy, snow. Accumulation 5-15 cm. Ridge wind moderate to strong, south. Temperature -5. Freezing level 800 m.

Avalanche Summary

On Wednesday several natural and skier triggered avalanches from size 1 to 1.5 where reported at treeline and alpine elevations. Most of these were failing on the recent January 15th crust however one ski cut result was believe to have failed on the January 6th crust at 1950 m on a north aspect.Reports from Tuesday indicate that the new snow had formed thin wind slabs that were reactive to skier triggers but had little mass or consequence. Expect this to change as new snow amounts accumulate with the approaching storm.On Sunday there was a report of a skier triggered size 2.5 slab avalanche in the northern part of the region that initiated as a 30 cm thick wind slab then stepped down to approximately 70 cm thick (likely the mid December layer) on a north-east aspect at 2050 m.

Snowpack Summary

Approximately 40-50 cm of new storm snow has buried the most recent, January 15th crust. This crust exists on almost all aspects and elevations with the exception of northerly aspects above 1850 m where the snow surface remained dry during the alpine inversion event on the weekend.Below the January 15th crust about 30-50 cm of snow overlies a 1 cm thick crust that was buried on January 6th which exists up to about 2000m. Mid and lower snowpack layers including the mid December and late November crust layers have produced moderate to hard, sudden results in snowpack tests in the northern part of the region last week and may be a concern for step-down potential.

Problems

Storm Slabs

An icon showing Storm Slabs
New snow and strong winds will build touchy storm slabs particulary on lee slopes at upper treeline and alpine elevations. In northern parts of the region it may still be possible for a surface release to step down to a deeper layer.
Minimize exposure during periods of heavy loading from new snow and wind or rain.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Valid until: Jan 19th, 2018 2:00PM