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Avalanche Forecast

Feb 1st, 2012–Feb 2nd, 2012
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Cariboos.

Confidence

Good - -1

Weather Forecast

A strong ridge of high pressure is expected to keep the region mostly clear and dry for the forecast period. Moderate northerly winds on Thursday are expected to shift to southerlies of Friday, before diminishing on Saturday. Freezing levels are expected to hover around 1000m on Thursday before spiking to 2000m on Friday, but back down to 1500m for Saturday.

Avalanche Summary

Recent reports include a couple of natural cornice-triggered 70-80cm thick wind slab avalanches as big as Size 3 on north and northeast facing alpine slopes. One natural Size 2.5, 80cm thick slab avalanche associated with the mid-January facets was observed on a southeast facing slope at 1600m. Check out the incident database (link under the Bulletins tab) for a report of a slope-cut stepping down to the mid-January facets in the Monkton Creek area near Barkerville. Large persistent slab avalanches that propagate across entire slopes are possible, especially with heavy triggers such as step-down avalanches and cornice falls. The recent storm snow also remains sensitive to human triggers with several small sluffs and Size 1 to 2, 35-45cm thick slab avalanches.

Snowpack Summary

Total snowpack depths are well above average or even new record depths for this time of year. Recent warm temperatures and upside-down storms created a touchy surface slab. Other weaknesses within and under (mid-January facets) the 100-150cm of settled storm snow create the potential for step-down avalanches, but things seem so be settling rapidly. Moderate southerly or southwesterly winds have created wind slabs and large fragile cornices in exposed lee and cross-loaded terrain. Snowpack tests on the mid-January facets consistently produce sudden fractures. This weakness seems to be particularly touchy below 1500m where there is an associated crust.

Avalanche Problems

Wind Slabs

Wind slabs are generally lurking below ridgecrests, behind terrain features and in cross-loaded gullies. They can fail as very large, destructive avalanches.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 6

Storm Slabs

Large storm slab avalanches have been occurring for the past week and are expected to remain sensitive to triggers for the forecast period.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 4

Cornices

Large cornices are looming over many slopes. Warm temperatures and solar radiation will likely weaken them. A falling chunk could trigger an avalanche on the slope below.

Aspects: North, North East, East, South East.

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 4