Avalanche Forecast

Issued: Mar 18th, 2019 4:41PM

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

Avalanche Canada swerner, Avalanche Canada

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Persistent warm temperatures are penetrating and destabilizing the upper snowpack. Natural avalanche activity is likely. Pay attention to sunny slopes and avoid travel under avalanche paths especially slopes with cornices overhead.

Summary

Confidence

Moderate -

Weather Forecast

Hot and sunny with freezing levels through the roof! No significant change during the forecast period. Very little temperature driven overnight re-freeze is expected. TUESDAY: Mostly clear skies and freezing levels holding strong above 3200 m. Alpine temperatures near + 7.0 degrees with a light southeast breeze at ridgetop. Alpine temperatures may drop to + 4.0 degrees overnight.WEDNESDAY: Repeat. Sunny skies with freezing levels above 3200 m. Alpine temperatures +7.0 degrees with light southeast ridgetop winds. Freezing levels may drop to 800 m overnight.THURSDAY: Sunny with some cloudy periods. Alpine temperatures near + 7.0 degrees and freezing levels 2800 m during the day.

Avalanche Summary

On Sunday, numerous natural avalanches were reported up to size 2.5 in the Duffey Lake area and avalanches were reported on solar aspects up the Railroad/Hurley Pass. In the southern part of the region (Coquihalla) numerous loose wet avalanches were reported up to size 1.5 from solar aspects and widespread snowballing was seen on the northerly aspects. As we enter a period of increased 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 natural avalanche activity will persist with the sunny skies and warming temperatures throughout the forecast period.

Snowpack Summary

Light amounts of new snow have been redistributed by southwesterly and northerly winds, potentially creating some unusual wind slabs, including on south-facing slopes. Beneath this recent snow you may find hard wind-affected snow at higher elevations, soft and faceted snow in shaded and sheltered areas, and melt-freeze crusts on southerly slopes. Currently, the snowpack is complex and with the continued warming and little overnight re-freeze we're very concerned about the upper 10 to 40 cm of snow that sits on a mix of facets and crust.The bigger questions are deeper in the snowpack. With little overnight re-freeze the warm temperatures will penetrate deeper allowing melt and a lot of water which will lubricate the upper snowpack. It also allows the upper snowpack to start creeping downhill at an accelerated rate. 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. We're not sure, but now is probably a time to let the mountains do their thing from afar and check back in when the freezing levels return to seasonal norms which could happen by next weekend.

Problems

Loose Wet

An icon showing Loose Wet
Loose wet activity is expected to continue on all aspects and elevations. Cornices are going to begin to loosen up and drop on the slopes below. You don't want to be under or near one of these 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.Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Wind Slabs

An icon showing Wind Slabs
A warm night followed by another day of clear skies and warm temperatures is expected to further destabilize the upper 10 to 40 cm of snow which will likely fail naturally.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Back off slopes as the surface becomes moist or wet with rising temperatures.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

1.5 - 2.5

Valid until: Mar 19th, 2019 2:00PM

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