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Archived

Avalanche Forecast

Mar 6th, 2016–Mar 7th, 2016
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
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: South Coast.

Give the new storm snow time to settle and strengthen before tackling big objectives.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Up to 10cm of new snow and moderate to strong southwest winds are forecast Saturday night. For the rest of the forecast period expect to see a mix of sun and cloud, isolated flurries and generally light ridgetop winds. The freezing level is expected to hover between 1000m and 1200m. The next storm is forecast to hit the region on Wednesday night.

Avalanche Summary

Backcountry observations have been limited, likely because of inclement weather, but I suspect there was a round of storm slab activity in response to new snow and wind over the weekend. Of note, an isolated yet destructive size 3 natural persistent slab avalanche was reported this week in the South Chilcotin area north of Goldbridge. The avalanche failed on surface hoar buried in early February. Cornices are large and fragile, and may also fail under the weight of a person.

Snowpack Summary

On Sunday 5-15cm of snow fell adding to the moderate amounts that had already fallen on Friday (up to 25cm in 24 hours). Storm totals from the past week were between 50-70cm. Strong southwesterly winds have shifted the new snow into deeper storm slabs on lee and cross-loaded alpine and treeline features. On all but higher elevation shaded slopes the new snow from Sunday likely overlies a melt-freeze crust from high freezing levels and sun on Saturday afternoon. Below the recent storm snow, the snowpack is generally strong and well-settled. That said, a layer of surface hoar buried at the beginning of February is a concern in the South Chilcotin area and can be found about 70cm below the surface. Although this layer is isolated, it has been responsible for destructive natural avalanche activity and is worth keeping on your radar if you're headed to the north of the region.

Avalanche Problems

Storm Slabs

The stormy weather has ended, but new storm slabs may remain sensitive to light inputs. I'd remain cautious of wind-loaded terrain at treeline and in the alpine. If the sun comes out on Monday, loose wet avalanches may also occur on solar aspects.
Be cautious as you transition into wind affected terrain.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Cornices

Cornices are reported to be very large and weak. Stay well back from ridgecrests, and watch your overhead hazard.
Extra caution needed around cornices with current conditions.>Cornices become weak with daytime heating. >

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 4