Avalanche Forecast

Issued: Jan 30th, 2019 3:59PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Persistent Slabs and Deep Persistent Slabs.

mconlan, Avalanche Canada

South Rockies.

Continue to use caution due to the weak layers buried in the snowpack.

Summary

Confidence

High -

Weather Forecast

WEDNESDAY NIGHT: Mostly clear skies, freezing level below valley bottom.THURSDAY: Increasing clouds over the day, light to moderate southwest winds, alpine temperature -5 C, freezing level 1000 m.FRIDAY: Mostly cloudy with light snowfall, accumulation 1 to 3 cm, light to moderate southwest winds, alpine temperature -1 C, freezing level 1800 m.SATURDAY: Mostly cloudy with light snowfall, accumulation 1 to 3 cm, light southwest winds, alpine temperature -3 C, freezing level below valley bottom.

Avalanche Summary

Evidence of a small avalanche triggered by a snowmobile was observed on Tuesday, releasing on the surface hoar layer described in the Snowpack Summary. Shooting cracks were also observed, suggesting instability with that layer. Otherwise, no new avalanches were observed.

Snowpack Summary

Around 10 to 30 cm of snow overlies a weak layer of feathery surface hoar crystals, with the most snow found at higher elevations. The surface hoar is most prominent between 1500 and 1900 m. The middle of the snowpack is generally consolidated. The bottom half of the snowpack is unconsolidated and composed of weak and sugary faceted grains.

Problems

Persistent Slabs

Around 10 to 30 cm of snow sits above a weak layer of feathery surface hoar crystals. The surface hoar is likely best preserved in shaded and sheltered areas between 1500 m and 1900 m.

Be careful with wind-loaded pockets, especially near ridge crests and roll-overs.Be very cautious in open terrain features, such as cutblocks, gullies, and cutbanks.If triggered, slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1 - 1.5

Deep Persistent Slabs

The bottom of the snowpack consists of weak and sugary faceted snow. There is a relatively low likelihood of triggering this layer, but the consequences remain high, as avalanches on this layer will be large and destructive.

Avoid steep, rocky terrain and shallow snowpack areas where triggering deep layers is more likely.Watch for signs of instability such as whumpfing, cracking, or recent avalanches.Use conservative route selection, such as moderate-angled and smooth terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 31st, 2019 2:00PM