Avalanche Forecast

Issued: Feb 21st, 2019 4:03PM

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

Avalanche Canada mconlan, Avalanche Canada

Recent observations of persistent slab avalanches and whumpfing indicate buried weak layers remain touchy. Wind slabs may also exist at higher elevations.

Summary

Confidence

High -

Weather Forecast

THURSDAY NIGHT: Clear skies, light to moderate west wind, alpine temperature -14 C.FRIDAY: Cloudy with light snowfall, accumulation 1 to 3 cm, moderate southwest wind, alpine temperature -13 C.SATURDAY: Cloudy with light snowfall, accumulation 2 to 5 cm, light northeast wind, alpine temperature -16 C.SUNDAY: Partly cloudy, light northeast wind, alpine temperature -17 C.

Avalanche Summary

An explosive triggered a large (size 2.5) persistent slab avalanche on Thursday. It was on a southerly aspect and between 1650 and 2000 m. The slab was about 40 cm deep.Last weekend, many persistent slab avalanches were observed. A skier triggered a large (size 2 to 2.5) avalanche within a slide path near Fernie. The avalanche was about 40 to 80 cm deep, on a northeast aspect, and at 1700 m. The South Rockies Field Team attended the site on Tuesday and confirmed that the avalanche failed on a layer of surface hoar, check out their report here. Also on Sunday a group of skiers remotely triggered a size 2 avalanche in the Little Sand area at 1650 m, as seen here. Cutblock-type terrain in the Rolling Hills has also been the source of persistent slab avalanches, see here.

Snowpack Summary

Wind slabs exist in open, exposed areas at higher elevations. They may be found on all aspects due to variable wind directions. In sheltered areas between 1600 and 1800 m, 20 cm of recent snow may sit on a weak layer of surface hoar crystals buried around Valentines Day in some locations.Two more weak layers of surface hoar may be found within the snowpack. Surface hoar that was buried early-February may be found about 30 to 50 cm deep in shaded and sheltered areas above 1600 m. The mid-January layer of surface hoar is buried around 70 to 100 cm and is most prominent between 1600 m and 1900 m.The remainder of the snowpack is well-settled.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Two weak layers of surface hoar may be found between 1500 m and 1900 m, around 40 to 80 cm deep in the snowpack. These layers have been the culprit of recent large avalanches, particularly in openings such as cutblocks, gullies, and slide paths.
Be aware of the potential for wide propagation.Make observations and assess conditions continually as you travel.Watch for signs of instability such as whumpfing, cracking, or recent avalanches.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

An icon showing Wind Slabs
Wind slabs may still be found at higher elevations in exposed terrain. Use particular caution near ridges or open areas where the snow feels stiff.
Keep an eye out for reverse loading due to variable winds.If triggered, wind slabs may step down to deeper layers resulting in large avalanches.Use caution in freshly wind-loaded features, especially near ridge crests and in steep terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 22nd, 2019 2:00PM