Avalanche Forecast

Issued: Feb 6th, 2019 4:55PM

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

cgarritty, Avalanche Canada

South Rockies.

Visible patterns of wind loading will help you to navigate around unstable pockets of wind slab. A less obvious persistent slab problem should have you raising your guard at mid elevations.

Summary

Confidence

Moderate -

Weather Forecast

Wednesday night: Clear with cloudy periods. Light west winds.Thursday: A mix of sun and cloud with isolated flurries and a trace of new snow, continuing overnight. Light to moderate southwest winds, increasing to strong northwest in the aline. Alpine high temperatures around -16.Friday: Cloudy with scattered flurries bringing up to 5 cm of low density new snow, continuing overnight. Light northeast winds. Alpine high temperatures around -21 and cooling over the day.Saturday: Mainly cloudy with easing flurries finishing with around 2 cm of new snow, bringing new snow totals to about 10 cm. Light northeast winds, with strong southeast winds in the alpine easing over the day. Alpine high temperatures around -24.

Avalanche Summary

No new avalanches were reported on Sunday. One observation of an older natural size 2 wind slab release was reported from the Castle area on Tuesday.Many small to large avalanches were triggered within the recent storm snow by skiers, naturally, and with explosives on Saturday. The fact that we have numerous weak layers within our snowpack indicates that conservative decisions should be made at this time.

Snowpack Summary

Above 1700 m, 25 to 35 cm of recent snow overlies a variety of surfaces, including feathery surface hoar crystals in shaded and sheltered areas, wind-affected snow in exposed terrain, and a melt-freeze crust on southerly aspects. Below 1700 m, expect to find around 5-10 cm of low-density snow on a melt-freeze crust.The mid-January layer of surface hoar or a crust is buried around 35 to 45 cm deep. The surface hoar is found on shaded and sheltered slopes and is most prominent between 1600 m and 1900 m but has been found up to 2100 m. The melt-freeze crust is found on south aspects at all elevations.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

A weak layer of surface hoar is now buried 35-45 cm deep. This layer has been regularly producing large avalanches in adjacent regions where it is only slightly deeper. It is best preserved in shaded, sheltered areas between 1600-1900 m.

Increase caution in open features at lower elevations, such as cutblocks, gullies, and cutbanks.Be aware of the potential for large avalanches due to the presence of buried surface hoar.Watch for signs of instability such as whumpfing, or cracking, especially from 1600-1900 m.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Wind Slabs

Recent snow may have been redeposited with southwest winds that switched to northeast winds. The touchiest pockets will likely be adjacent to ridges.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Be careful with wind-loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The bottom of the snowpack consists of weak and sugary faceted snow. The likelihood of triggering this layer may be relatively low, but the consequences remain high. Any deep persistent slab avalanche 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 - 3.5

Valid until: Feb 7th, 2019 2:00PM