Archived

Avalanche Forecast

Feb 15th, 2017–Feb 16th, 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 into a period of HIGH danger with rapid loading of the snowpack on Wednesday into Thursday: rain to treeline and heavy snow in the alpine.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Warm and wet still on Thursday. Cooling with isolated flurries on Friday, and improving for Saturday. THURSDAY: Rain or wet snow (25-40 mm / cm) with even higher amounts possible for the Coquihalla / Moderate to strong southerly winds in the afternoon / Freezing level around 1600 m. FRIDAY: Mostly cloudy with locally heavy flurries possible (5-15cm) / High temperatures to -1 Celsius / Light westerly winds / Freezing level around 1200 m. SATURDAY: Cloudy with sunny periods / Ridge winds light southerly / Freezing level around 900m / High temperatures to -2 Celsius.

Avalanche Summary

Limited observations during this storm.In the Duffey Lake zone a Size 2.5 deep persistent slab was reported running on a south-southwesterly aspect near 2200m, likely triggered by solar warming on Monday or Tuesday.

Snowpack Summary

In the Duffey Lake area 25 cm of snow fell on Tuesday in to Wednesday. In the south (Coquihalla) we had moderate southerly winds and heavy rain above 1600m on Tuesday night (and rain to 2000m during the day Wednesday). This new rain (or snow higher up) sits on either wind slabs in the alpine or temperature crusts at treeline and below, especially on east and south aspects. Both of these surfaces will be good sliding layers for future snowfall. 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 the warming and extra loading this 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 (especially in the south) 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.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

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