Archived

Avalanche Forecast

Feb 14th, 2017–Feb 15th, 2017

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

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

Regions: South Coast Inland.

We're moving into a period of HIGH danger with rapid loading of the snowpack on Wednesday and Thursday: rain to treeline and heavy snow in the alpine.

Confidence

Low - Intensity of incoming weather systems is uncertain

Weather Forecast

Warm and wet on Wednesday - Thursday. Cooling with light preciptation on Friday. WEDNESDAY: Rain to treeline (30-50mm) ; wet heavy snow in the alpine (30-50cm) / Strong southerly winds becoming moderate / Freezing level around 2300m / High temperatures to +3 Celsius. THURSDAY: Wet snow (20-30cm Coquihalla ; 30-50cm Duffey Lake road) / Moderate southeasterly winds / Freezing level around 1300 m. FRIDAY: Mostly cloudy with isolated flurries / High temperatures to +1 Celsius / Light-moderate southerly winds / Freezing level around 1100 m.

Avalanche Summary

On Monday there were several loose wet avalanches to Size 2 on solar (southerly) aspects, and some moist slabs to size 1.5 as well.

Snowpack Summary

The recent warming and sunny conditions gave us a widespread sun crust on all but high northerly (and some westerly) aspects, where there is still some cold snow to be found. Last week we had 60-80cm storm snow (lower amounts in the north), which fell with moderate to strong southwest winds.The main concern in the Duffey zone is lingering storm and wind slabs, which have given moderate resistant and sudden results (down 30-40cm and also 60-70cm) in snowpack tests (see above for more information). On the Coquihalla, a temperature crust can be found up to 1800m and significant wind effect occurred at upper treeline and alpine elevations.The mid-December facets down 130-160 cm still remain a concern especially in shallower snowpack areas in the Duffey, Hurley and/ or South Chilcotins. These deeper weaknesses warrant monitoring, especially with rapid warming next week. In southern areas (Coquihalla), the lower snowpack is reportedly well settled (stronger), than it is to the north.

Avalanche Problems

Loose Wet

Heavy rain at treeline and below will cause the snow to become soft and cohesionless. Avoid getting pushed into terrain features like gullies and cliffs, where even small slides could have large consequences.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.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

Expected Size: 1 - 2

Storm Slabs

The warming trend, strong winds and heavy precipitation will make storm and wind slab avalanches likely in the alpine.

Use caution in lee areas in the alpine and treeline. Recent storm snow has formed touchy slabs.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 3

Persistent Slabs

This problem is more prevalent in the far north areas of the region and is a low likelihood, high consequence scenario that will need to be monitored as snow loads or temperatures increase.

Be cautious in shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4