Avalanche Forecast Cariboos

Tuesday 12th February 2019

Avalanche Danger Ratings Tue 12th Feb 4:07PM Danger Ratings Alpine: Moderate Danger Ratings Treeline: Moderate Danger Ratings Below Treeline: Moderate Persistent Slabs Persistent Slabs Wind Slabs Wind Slabs

Avalanche Canada Forecaster: mbender

Date Issued:

Valid Until:

Although the likelihood of triggering an avalanche has diminished (hence the moderate rating) the consequence of triggering an avalanche is significant. Check out the Forecaster Blog here.

Confidence

High -

Weather Forecast

TUESDAY Night: Mainly cloudy with clear periods, light southeast wind, Alpine temperature -19 CWEDNESDAY: Mix of sun and cloud, light southwest wind, alpine temperature -14 C.THURSDAY: Mix of sun and cloud, light to moderate southeast wind, alpine temperature -12 C.FRIDAY: Flurries, accumulation 5 cm, light east wind, alpine temperature -10 C

Avalanche Summary

A snowmobiler died in a large (size 2) slab avalanche on Saturday just outside this region in the North Columbias (report here). The avalanche was triggered by the rider at 2100 m on a south aspect. The crown fracture varied from 15-100 cm deep, suggesting wind loading was a factor in the incident.On Sunday there was a small human-triggered avalanche was reported from a north aspect at 2100 m. It failed around 35 cm deep on the mid-January surface hoar layer. Although written several days ago, this MIN post describing conditions in Allen Creek is still relevant.

Snowpack Summary

A touchy weak layer responsible for a several close calls and surprise avalanches lies approximately 50 cm below the surface (30 cm in shallow areas, 60 cm or more in deeper spots). This weak layer was buried mid-January and comprises a mix of surface hoar and facets. On southerly aspects, it lies on top of a sun crust. This is a dangerous weak layer that is shallow enough to be easily triggered but deep enough to produce large avalanches. It is most prevalent at treeline and below treeline elevations, but there have been a few reports of its presence in sheltered areas in the alpine.Strong northerly and easterly winds have created complicated patterns of wind-loaded snow.Average snow depths are approximately 270 cm. Lower layers in the snowpack are not a significant factor at this time.

Persistent Slabs Persistent Slabs

Likelihood

Possible

Expected Size

1.5 - 3

Approximately 50 cm of snow sits above a persistent weak layer of surface hoar and crust that was buried in mid-January. This layer continues to be reactive to human triggering.

Avoid convexities as well as steep, open and/or sparsely treed slopes at and below treeline.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Any steep opening in the trees should be treated as suspect right now.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

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Wind Slabs Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

Many locations have been hit hard by winds over the last few days forming wind slabs in the lee of terrain features on a variety of aspects. There is potential for a wind slab avalanche to step-down to a persistent weak layer below.

Back off if you encounter whumpfing, hollow sounds, or shooting cracks.Avoid areas where the snow feels stiff and/or slabby.If triggered, wind slabs may step down to deeper layers and result in even larger avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

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