Avalanche Forecast

Issued: Mar 20th, 2019 3:47PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Loose Wet and Wet Slabs.

swerner, Avalanche Canada

South Coast Inland.

Natural avalanche activity is possible especially on sun exposed slopes in the afternoon. Cornices are soft and weak. Avoid travel under, on or anywhere near cornices.

Summary

Confidence

Moderate -

Weather Forecast

THURSDAY: A mix of sun and cloud. Freezing levels 2800 m on the Coquihalla and 1600 m on the Duffy. Alpine temperatures near +5 degrees. Ridgetop winds light from the southeast.FRIDAY: Cloudy. Freezing levels and alpine temperatures are the same as Thursday. Ridgetop winds light from the southeast.SATURDAY: Cloudy with light precipitation (5-10 mm) falling as rain at treeline and below treeline and snow in the alpine. Freezing levels 1500 m and alpine temperatures falling to -2. Ridgetop winds light from the South.

Avalanche Summary

On Wednesday, a few natural loose wet avalanches were reported from steep solar slopes. On Tuesday, a natural loose wet avalanche cycle continued on sunny aspects (SE-W) up to size 3, some of these triggered thin slabs. On shady aspects (NW-NE) some slabs up to size 2 ran naturally. The crowns were 30-40 cm deep and we suspect they ran on a facet layer that developed during the cold spell in February.With continued warming it's worth reminding ourselves that glide cracks are to be avoided at all times. They're incredibly unpredictable and when they fail, they often fail big. Glide avalanche concerns are especially important to consider in the Coquihalla area. A recent social media post from a professional in this part of the region does a great job of highlighting the issue. (Link here) A glide failed naturally on a southeast facing slope around 1000 m on Saturday.We suspect that natural avalanche activity will slowly decrease as temperatures drop over the weekend.

Snowpack Summary

Snow surfaces are highly variable. On higher elevation north aspects (above 1900 m) you may find dry, faceted snow. Some of this has been redistributed by southwesterly and northerly winds, potentially creating some unusual wind slabs. On solar aspects (East, South, West) moist snow exists creating melt-freeze conditions at higher elevations and mostly just melt conditions below treeline. The bigger questions are deeper in the snowpack. Down 40-60 cm below the melt-freeze crust on solar aspects and the wintery snow on the polar aspects sits the February facet interface. The warm temperatures will continue to penetrate deeper and destabilize the snowpack. Its hard to say how many hot days and warm nights it will it take to wake up the more deeply buried weak layers that we haven't thought about in a long time.

Problems

Loose Wet

Loose wet activity is expected to continue on all aspects and elevations except north facing, alpine slopes. Cornices are softening up and weak. You don't want to be under or near one of these looming monsters when they fail.

Loose avalanches may start small but they can gain mass and push you into dangerous terrain.Cornices become weak with daytime heating or solar exposure.

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Wet Slabs

As the warming penetrates deeper in the snowpack large wet slabs may fail naturally, especially where buried crust or facet interfaces exist. Avoid avalanche terrain, especially when it's baking in the sun.

Avoid exposure to overhead slopes with Glide Cracks. Avalanches may reach the end of run out zones.Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Mar 21st, 2019 2:00PM