Avalanche Forecast

Issued: Mar 3rd, 2019 3:43PM

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.

shorton, Avalanche Canada

Lizard-Flathead.

Persistent slab avalanches continue to pose a low likelihood, high consequence problem at lower elevations.

Summary

Confidence

Moderate -

Weather Forecast

SUNDAY NIGHT: Clear, light northeast wind, alpine temperatures drop to -20 C.MONDAY: Sunny, light northeast wind, alpine high temperatures near -12 C.TUESDAY: Sunny with cloudy periods, light northeast wind, alpine high temperatures near -8 C.WEDNESDAY: Cloudy with isolated flurries, light southeast wind with moderate gusts, alpine high temperatures near -10 C.

Avalanche Summary

A few small (size 1) wind slab avalanches and loose dry sluffs were reported over the weekend. On Friday, numerous natural, human, and explosive triggered storm slabs (size 1-2) were reported during the storm.

Snowpack Summary

20-40 cm of low density snow is gradually settling and has potentially blown into wind slabs in exposed terrain. The snow sits on older wind slabs at upper elevations, which will be difficult to detect now that they are buried. In sheltered areas and below treeline, the new snow sits on facets (sugary snow) and surface hoar (feathery crystals), and a crust on south-facing slopes.There are potentially three layers of surface hoar in the top 100 cm of the snowpack. One is down 30-50 cm, another is down 40-80 cm, and the last one is down 80-110 cm. These layers have been most prominent and reactive between 1600-1900 m.The lower portion of the snowpack is generally strong.

Problems

Persistent Slabs

Several surface hoar layers in the top metre of the snowpack have been the culprit in large avalanches over the past month. They are most prominent between 1600-1900 m, particularly in openings such as cutblocks, gullies, and slide paths.

Be aware of the potential for wide propagation.Use caution on open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 2.5

Wind Slabs

Recent snow has likely formed wind slabs that could be reactive to human triggering at upper elevations.

Be cautious as you transition into wind affected terrain.If triggered, wind slabs may step down to deeper layers resulting in large avalanches.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 1.5

Valid until: Mar 4th, 2019 2:00PM